Search Results

Search found 17195 results on 688 pages for 'input'.

Page 411/688 | < Previous Page | 407 408 409 410 411 412 413 414 415 416 417 418  | Next Page >

• SSH not working over IPSec tunnel (Strongswan)

  - by PattPatel

  I configured a small network on a cloud virtual machine. This virtual machine has a static IP address assigned to eth0 interface that I'll call $EXTIP. mydomain.com points to $EXTIP. Inside, I have some linux containers, that get their ip through DHCP in the Subnet 10.0.0.0/24 (i called the virtual interface nat ). They run some services that can be reached through DNAT. Then I wanted to connect to these containers through an IPSec tunnel, so I configured StrongSwan. ipsec.conf: conn %default dpdaction=none rekey=no conn remote keyexchange=ikev2 ike=######## left=[$EXTIP] leftsubnet=10.0.1.0/24,10.0.0.0/24 leftauth=pubkey lefthostaccess=yes leftcert=########.pem leftfirewall=yes leftid="#########" right=%any rightsourceip=10.0.1.0/24 rightauth=######## rightid=%any rightsendcert=never eap_identity=%any auto=add type=tunnel Everything works fine, IPSec clients get IPs of the 10.0.1.0/24 subnet and can reach the containers subnet. My problem is that I'm not able to get SSH connections over the tunnel. It simply does not work, ssh client does not produce any output. Sniffing with tcpdump gives: tcpdump: 09:50:29.648206 ARP, Request who-has 10.0.0.1 tell mydomain.com, length 28 09:50:29.648246 ARP, Reply 10.0.0.1 is-at 00:ff:aa:00:00:01 (oui Unknown), length 28 09:50:29.648253 IP mydomain.com.54869 > 10.0.0.1.ssh: Flags [S], seq 4007849772, win 29200, options [mss 1460,sackOK,TS val 1151153 ecr 0,nop,wscale 7], length 0 09:50:29.648296 IP 10.0.0.1.ssh > 10.0.1.2.54869: Flags [S.], seq 2809522632, ack 4007849773, win 14480, options [mss 1460,sackOK,TS val 11482992 ecr 1151153,nop,wscale 6], length 0 09:50:29.677225 IP mydomain.com.54869 > 10.0.0.1.ssh: Flags [.], ack 2809522633, win 229, options [nop,nop,TS val 1151162 ecr 11482992], length 0 09:50:29.679370 IP mydomain.com.54869 > 10.0.0.1.ssh: Flags [P.], seq 0:23, ack 1, win 229, options [nop,nop,TS val 1151162 ecr 11482992], length 23 09:50:29.679403 IP 10.0.0.1.ssh > 10.0.1.2.54869: Flags [.], ack 24, win 227, options [nop,nop,TS val 11483002 ecr 1151162], length 0 09:50:29.684337 IP 10.0.0.1.ssh > 10.0.1.2.54869: Flags [P.], seq 1:32, ack 24, win 227, options [nop,nop,TS val 11483003 ecr 1151162], length 31 09:50:29.685471 IP 10.0.0.1.ssh > 10.0.1.2.54869: Flags [.], seq 32:1480, ack 24, win 227, options [nop,nop,TS val 11483003 ecr 1151162], length 1448 09:50:29.685519 IP mydomain.com > 10.0.0.1: ICMP mydomain.com unreachable - need to frag (mtu 1422), length 556 09:50:29.685567 IP 10.0.0.1.ssh > 10.0.1.2.54869: Flags [.], seq 32:1402, ack 24, win 227, options [nop,nop,TS val 11483003 ecr 1151162], length 1370 09:50:29.685572 IP 10.0.0.1.ssh > 10.0.1.2.54869: Flags [.], seq 1402:1480, ack 24, win 227, options [nop,nop,TS val 11483003 ecr 1151162], length 78 09:50:29.714601 IP mydomain.com.54869 > 10.0.0.1.ssh: Flags [.], ack 32, win 229, options [nop,nop,TS val 1151173 ecr 11483003], length 0 09:50:29.714642 IP 10.0.0.1.ssh > 10.0.1.2.54869: Flags [P.], seq 1480:1600, ack 24, win 227, options [nop,nop,TS val 11483012 ecr 1151173], length 120 09:50:29.723649 IP mydomain.com.54869 > 10.0.0.1.ssh: Flags [P.], seq 1393:1959, ack 32, win 229, options [nop,nop,TS val 1151174 ecr 11483003], length 566 09:50:29.723677 IP 10.0.0.1.ssh > 10.0.1.2.54869: Flags [.], ack 24, win 227, options [nop,nop,TS val 11483015 ecr 1151173,nop,nop,sack 1 {1394:1960}], length 0 09:50:29.725688 IP mydomain.com.54869 > 10.0.0.1.ssh: Flags [.], ack 1480, win 251, options [nop,nop,TS val 1151177 ecr 11483003], length 0 09:50:29.952394 IP 10.0.0.1.ssh > 10.0.1.2.54869: Flags [P.], seq 1480:1600, ack 24, win 227, options [nop,nop,TS val 11483084 ecr 1151173,nop,nop,sack 1 {1394:1960}], length 120 09:50:29.981056 IP mydomain.com.54869 > 10.0.0.1.ssh: Flags [.], ack 1600, win 251, options [nop,nop,TS val 1151253 ecr 11483084,nop,nop,sack 1 {1480:1600}], length 0 If you need it this is my iptables configuration file: iptables: *filter :INPUT ACCEPT [144:9669] :FORWARD DROP [0:0] :OUTPUT ACCEPT [97:15649] :interfacce-trusted - [0:0] :porte-trusted - [0:0] -A FORWARD -m conntrack --ctstate RELATED,ESTABLISHED -j ACCEPT -A FORWARD -j interfacce-trusted -A FORWARD -j porte-trusted -A FORWARD -j REJECT --reject-with icmp-host-unreachable -A FORWARD -d 10.0.0.1/32 -p tcp -m tcp --dport 80 -m state --state NEW,RELATED,ESTABLISHED -j ACCEPT -A FORWARD -d 10.0.0.1/32 -p tcp -m tcp --dport 443 -m state --state NEW,RELATED,ESTABLISHED -j ACCEPT -A FORWARD -d 10.0.0.3/32 -p tcp -m tcp --dport 1234 -m state --state NEW,RELATED,ESTABLISHED -j ACCEPT -A interfacce-trusted -i nat -j ACCEPT -A porte-trusted -d 10.0.0.1/32 -p tcp -m tcp --dport 80 -j ACCEPT -A porte-trusted -d 10.0.0.1/32 -p tcp -m tcp --dport 443 -j ACCEPT -A porte-trusted -d 10.0.0.3/32 -p tcp -m tcp --dport 1234 -j ACCEPT COMMIT *nat :PREROUTING ACCEPT [10:600] :INPUT ACCEPT [10:600] :OUTPUT ACCEPT [4:268] :POSTROUTING ACCEPT [18:1108] -A PREROUTING -d [$EXTIP] -p tcp -m tcp --dport 80 -j DNAT --to-destination 10.0.0.1:80 -A PREROUTING -d [$EXTIP] -p tcp -m tcp --dport 443 -j DNAT --to-destination 10.0.0.1:443 -A PREROUTING -d [$EXTIP] -p tcp -m tcp --dport 8069 -j DNAT --to-destination 10.0.0.3:1234 -A POSTROUTING -s 10.0.0.0/24 -o eth0 -m policy --dir out --pol ipsec -j ACCEPT -A POSTROUTING -s 10.0.1.0/24 -o nat -j MASQUERADE -A POSTROUTING -s 10.0.0.0/24 -o eth0 -j MASQUERADE COMMIT Probably I'm missing something stupid... Thanks in advance for helping :))

  Read the article

• How can I assign the keyboard shortcut ?x to the command move to trash?

  - by Fra

  In the Finder in Leopard I used to have the command "move to trash" associated with the keyboard shortcut ?x which was very handy because you could input the command with one hand. Moreover on the keyboard x is near to c, s and a which are other shortcuts often used in Finder. Now in Lion the command "move to trash" is associated to ? ? but I don't like it. How can I assign the keyboard shortcut ?x to the command "move to trash"?

  Read the article

• Is the development of CLI apps considered "backward"?

  - by user61852

  I am a DBA fledgling with a lot of experience in programming. I have developed several CLI, non interactive apps that solve some daily repetitive tasks or eliminate the human error from more complex albeit not so daily tasks. These tools are now part of our tool box. I find CLI apps are great because you can include them in an automated workflow. Also the Unix philosophy of doing a single thing but doing it well, and letting the output of a process be the input of another, is a great way of building a set of tools than would consolidate into an strategic advantage. My boss recently commented that developing CLI tools is "backward", or constitutes a "regression". I told him I disagreed, because most CLI tools that exist now are not legacy but are live projects with improved versions being released all the time. Is this kind of development considered "backwards" in the market? Does it look bad on a rèsumè? I also considered all solutions whether they are web or desktop, should have command line, non-interactive options. Some people consider this a waste of programming resources. Is this goal a worthy one in a software project?

  Read the article

• Server being used to send spam mail. How do I investigate?

  - by split_account

  Problem I think my server is being used to send spam with sendmail, I'm getting a lot of mail being queued up that I don't recognize and my mail.log and syslog are getting huge. I've shutdown sendmail, so none of it is getting out but I can't work out where it's coming from. Investigation so far: I've tried the solution in the blog post below and also shown in this thread. It's meant to add a header from wherever the mail is being added and log all all mail to file, so I changed the following lines in my php.ini file: mail.add_x_header = On mail.log = /var/log/phpmail.log But nothing is appearing in the phpmail.log. I used the command here to investigate cron jobs for all users, but nothing is out of place. The only cron being run is the cron for the website. And then I brought up all php files which had been modified in the last 30 days but none of them look suspicious. What else can I do to find where this is coming from? Mail.log reports Turned sendmail back on for second. Here is a small sample of the reports: Jun 10 14:40:30 ubuntu12 sm-mta[13684]: s5ADeQdp013684: from=<>, size=2431, class=0, nrcpts=1, msgid=<[email protected]>, proto=ESMTP, daemon=MTA-v4, relay=localhost [127.0.0.1] Jun 10 14:40:30 ubuntu12 sm-msp-queue[13674]: s5ACK1cC011438: to=www-data, delay=01:20:14, xdelay=00:00:00, mailer=relay, pri=571670, relay=[127.0.0.1] [127.0.0.1], dsn=2.0.0, stat=Sent (s5ADeQdp013684 Message accepted for delivery) Jun 10 14:40:30 ubuntu12 sm-mta[13719]: s5ADeQdp013684: to=<[email protected]>, delay=00:00:00, xdelay=00:00:00, mailer=local, pri=32683, dsn=2.0.0, stat=Sent Jun 10 14:40:30 ubuntu12 sm-mta[13684]: s5ADeQdr013684: from=<[email protected]>, size=677, class=0, nrcpts=1, msgid=<[email protected]>, proto=ESMTP, daemon=MTA-v4, relay=localhost [127.0.0.1] Jun 10 14:40:31 ubuntu12 sm-msp-queue[13674]: s5AC0gpi011125: to=www-data, ctladdr=www-data (33/33), delay=01:39:49, xdelay=00:00:01, mailer=relay, pri=660349, relay=[127.0.0.1] [127.0.0.1], dsn=2.0.0, stat=Sent (s5ADeQdr013684 Message accepted for delivery) Jun 10 14:40:31 ubuntu12 sm-mta[13721]: s5ADeQdr013684: to=<[email protected]>, ctladdr=<[email protected]> (33/33), delay=00:00:01, xdelay=00:00:00, mailer=local, pri=30946, dsn=2.0.0, stat=Sent Jun 10 14:40:31 ubuntu12 sm-mta[13684]: s5ADeQdt013684: from=<[email protected]>, size=677, class=0, nrcpts=1, msgid=<[email protected]>, proto=ESMTP, daemon=MTA-v4, relay=localhost [127.0.0.1] Jun 10 14:40:31 ubuntu12 sm-msp-queue[13674]: s5ACF2Nq011240: to=www-data, ctladdr=www-data (33/33), delay=01:25:29, xdelay=00:00:00, mailer=relay, pri=660349, relay=[127.0.0.1] [127.0.0.1], dsn=2.0.0, stat=Sent (s5ADeQdt013684 Message accepted for delivery) Jun 10 14:40:31 ubuntu12 sm-mta[13723]: s5ADeQdt013684: to=<[email protected]>, ctladdr=<[email protected]> (33/33), delay=00:00:00, xdelay=00:00:00, mailer=local, pri=30946, dsn=2.0.0, stat=Sent Ju Further Investigation Spotted 4 spam accounts registered in the past day, which is suspicious however all have normal user privileges. There are no contact forms on the site, there are a number of forms and they take either filtered text input or plain text input. Mail is still being queued up having switched the website to maintenance mode, which blocks out everyone but the admin. Ok more investigation, it looks like the email is being send by my websites cron which runs every 5 minutes. However there are no cron jobs I've set-up which run more than once an hour and show on the website log so presumably someone has managed to edit my cron somehow. Copy of email: V8 T1402410301 K1402411201 N2 P120349 I253/1/369045 MDeferred: Connection refused by [127.0.0.1] Fbs $_www-data@localhost ${daemon_flags}c u Swww-data [email protected] MDeferred: Connection refused by [127.0.0.1] C:www-data rRFC822; [email protected] RPFD:www-data H?P?Return-Path: <?g> H??Received: (from www-data@localhost) by ubuntu12.pcsmarthosting.co.uk (8.14.4/8.14.4/Submit) id s5AEP13T015507 for www-data; Tue, 10 Jun 2014 15:25:01 +0100 H?D?Date: Tue, 10 Jun 2014 15:25:01 +0100 H?x?Full-Name: CronDaemon H?M?Message-Id: <[email protected]> H??From: root (Cron Daemon) H??To: www-data H??Subject: Cron <www-data@ubuntu12> /usr/bin/drush @main elysia-cron H??Content-Type: text/plain; charset=ANSI_X3.4-1968 H??X-Cron-Env: <PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin> H??X-Cron-Env: <COLUMNS=80> H??X-Cron-Env: <SHELL=/bin/sh> H??X-Cron-Env: <HOME=/var/www> H??X-Cron-Env: <LOGNAME=www-data>

  Read the article

• Cannot copy MP3 files from a CD

  - by MountainX

  I purchased a set of spoken word audio CD's that have MP3 and FLAC audio files; I think they also play as regular audio CD's because I see a CDA directory and .cda files. But I'm only interested in playing the MP3 files by copying them to my phone. Dolphin file manager shows all the files on the CD. However, it will not copy any of them to my hard drive, which is what my goal is. Dolphin shows no error, but the copy progress is zero. Amarok will play the files but not easily. I only tried the flac files. To play a file, I click the file in Dolphin, then I have to cancel a job using KDE's notification system, then Amarok proceeds to copy the file to a tmp directory which takes a long time, then it finally plays. kb3 will rip the audio, but I would prefer to copy the files directly from the CD. Since Dolphin would not copy the files, I thought I would try the terminal, but I can't get that to work either. mount -t auto -o ro /dev/sr0 /mnt/temp that gives the error: wrong fs type, bad option, bad superblock, etc. I get the same error using -t iso9660 and -t udf. so I started troubleshooting: ~$ wodim --devices wodim: Overview of accessible drives (1 found) : ------------------------------------------------------------------------- 0 dev='/dev/sg1' rwrw-- : 'MATSHITA' 'DVD-RAM UJ8A0AS' ------------------------------------------------------------------------- /dev/sg1 is not a block device sudo file -s /dev/sr0 ERROR: cannot read /dev/sr0 (input/output error) sudo file -s /dev/sg1 just hangs How can I copy these files to my computer hard disk?

  Read the article

• Is there a visual web application builder or rapid webapp prototyping framework?

  - by Jesper Mortensen

  Question: Is there such a thing as a self-hosted framework or CMS especially tailored towards the creation of interactive web applications without -- or with an absolute minimum of -- programming? (Substantially less programming than say a simple Rails app or a plugin for Wordpress, Joomla etc would require.) As for desired features I'd settle for whatever is available, but some ideas could be: A User authentication and Permissions system. A GUI-driven input form builder. A GUI-driven template / visual site design builder. A simple scripting language (think AppleScript-like simplicity) A highly modular architecture, with high-level business objects (users, forms data, etc) exposed for easy re-use. If something like the above doesn't exist, then what comes near this? Need: This is for self-hosted rapid prototyping of web applications, and limited user testing of webapp user interface designs in a closed user test. Notes: I know about Ruby on Rails (Rails), Django, Pyramid etc. I'm looking for something much faster to work in, for making prototypes. I know about CMS's in general but find that most of them are tailored towards displaying information to the end users. If there is an exceptionally easy-to-master CMS with easy scripting (lets say much more so than for example Wordpress) then I'd be interested.

  Read the article

• Unity: parallel vectors and cross product, how to compare vectors

  - by Heisenbug

  I read this post explaining a method to understand if the angle between 2 given vectors and the normal to the plane described by them, is clockwise or anticlockwise: public static AngleDir GetAngleDirection(Vector3 beginDir, Vector3 endDir, Vector3 upDir) { Vector3 cross = Vector3.Cross(beginDir, endDir); float dot = Vector3.Dot(cross, upDir); if (dot > 0.0f) return AngleDir.CLOCK; else if (dot < 0.0f) return AngleDir.ANTICLOCK; return AngleDir.PARALLEL; } After having used it a little bit, I think it's wrong. If I supply the same vector as input (beginDir equal to endDir), the cross product is zero, but the dot product is a little bit more than zero. I think that to fix that I can simply check if the cross product is zero, means that the 2 vectors are parallel, but my code doesn't work. I tried the following solution: Vector3 cross = Vector3.Cross(beginDir, endDir); if (cross == Vector.zero) return AngleDir.PARALLEL; And it doesn't work because comparison between Vector.zero and cross is always different from zero (even if cross is actually [0.0f, 0.0f, 0.0f]). I tried also this: Vector3 cross = Vector3.Cross(beginDir, endDir); if (cross.magnitude == 0.0f) return AngleDir.PARALLEL; it also fails because magnitude is slightly more than zero. So my question is: given 2 Vector3 in Unity, how to compare them? I need the elegant equivalent version of this: if (beginDir.x == endDir.x && beginDir.y == endDir.y && beginDir.z == endDir.z) return true;

  Read the article

• Finishing an iteration early

  - by f1dave

  I'd like some input on this on those working with agile methodologies... A current project is finding that development on our planned user stories is finishing some time before the end of the iteration, and that the testing effort and business acceptance is what's actually dragging us out longer towards the end. This means that the devs in question have spare time, and they're essentially going out to the iteration+1 backlog and starting work on cards there before our current iteration cards are 'done'. As iteration manager, I want to put a stop to this - I want a more team-orientated approach where the group takes ownership of getting all the cards done, as opposed to "Well, dev's done so what do I dev next?" The problem I face is convincing the team of this. On one hand, I understand why the devs don't want to test the code they've written (there are unit tests they write of course, but the manual testing to be done could be influenced by their bias). The team sees working ahead as making our next iterations easier, because a lot of the work is done before we start. I see this as screwing with the whole system of planning/actuals - but it's difficult to convince the team as to why this matters. What advice can you guys and girls give? How do we stop devs reaching ahead? What should they be doing instead? How much of a problem is this in the scheme of things, if things are still getting done?

  Read the article

• Is there a path from OpenSCAD to WebGL?

  - by Andrew Domaszek

  tl;dr version, Does a software path exist to convert from openscad input to render on a website via webgl? What I'm trying to do is display OpenSCAD created designs uploaded via post on a LEMPy driven website; this is currently done by outputting to a static png image. I would like to render one of openscad's export formats(wikibooks) and convert for display in javascript/webgl through some software path available via linux batch. CPU and RAM are relatively unconstrained but no GPU available. I've looked into CopperLeicht, but it requires CopperCube output which would require windows or wine. FOSS is preferred but not required. edit: I found three.js has converters for fbx, dae, obj, and 3ds formats which might be helpful as one of the last steps.

  Read the article

• Why has Google toolbar has stopped working in Firefox 3.6.8?

  - by DanM

  Yesterday, I noticed that my Google Toolbar has stopped working. The toolbar is still there, but it is completely blank (no buttons or input fields, just a gray strip of nothing). In addition to this, tooltips have stopped working. If I disable the toolbar, the tooltips return to normal, so that particular problem definitely seems to be a side effect of the toolbar. I tried disabling all my other add-ons, but that made no difference. I also tried uninstalling and reinstalling Google Toolbar. That made no difference. I haven't tried reinstalling the browser, but I'm reluctant to do that unless absolutely necessary. Am I the only one having this problem? Any ideas how to fix? Note: I'm running Windows XP SP3. I'm using Google Toolbar version 7.1.20100723W.

  Read the article

• Turn-based tile game dynamic item/skill/command script files

  - by user1542

  I want to create a mechanism that could read text script, for example some kind of custom script such as ".skill" or ".item", which maybe contain some sort of simple script like .item Item.Name = "Strength Gauntlet"; Character.STR += 20; .. .skill Skill.Name = "Poison Attack"; Skill.Description = "Steal HP and inflict poison"; Player.HP += 200; Enemy.HP -= 200; Enemy.Status += Status.POISON; It may be different from this, but just want to give some idea of what I desire. However, I do not know how to dynamically parse these things and translate it into working script. For example, in battle scenerio, I should make my game read one of this ".skill" file and apply it to the current enemy, or the current player. How would I do this? Should I go for String parsing? It is like a script engine, but I prefer C# than creating new language, so how would I parse custom files into appropiate status commands? Another problem is, I have also created a command engine which would read String input and parse it into action such as "MOVE (1,2)" would move character to tile (1,2). Each command belong to separate class, and provide generic parsing method that should be implemented by hand. This is for the reason of custom number/type of arguments per each command. However, I think this is not well designed, because I desire it to automatically parse the parameters according to specify list of types. For example, MOVE command in "MOVE 1 2" would automatically parse the parameters into int, int and put it into X and Y. Now, this form can change, and we should be able to manually specify all type of formats. Any suggestion to this problem? Should I change from string parsing to some hardcode methods/classes?

  Read the article

• Visual Studio 2010 on Macbook Air

  - by Kyle B.

  Does anyone here run Visual Studio 2010 (or VS12 RC) on a Macbook Air? I have the current model with 4GB ram, 13" screen, and 256GB SSD drive. Before I go through the effort of configuring this, I'd like to know if anyone from the community has done this and: Was the performance acceptable? If it is, I plan to get a larger cinema display monitor as a second display and do all my coding on this machine ditching my desktop. Did you use Boot camp, Parallels, or VMWare? I feel to maximize performance that boot camp would be necessary to make the most utilization of the memory, but am not sure if this completely necessary. I'd prefer to use a VM, but wasn't sure if this was practical and would value your input before buying a license. Did you also run anything else on the Windows installation, such as SQL Server express, IISExpress, etc? Did performance lag after a certain point? Note: I would have asked this in superuser.com, but felt this applied more directly to the programming community.

  Read the article

• Why unhandled exceptions are useful

  - by Simon Cooper

  It’s the bane of most programmers’ lives – an unhandled exception causes your application or webapp to crash, an ugly dialog gets displayed to the user, and they come complaining to you. Then, somehow, you need to figure out what went wrong. Hopefully, you’ve got a log file, or some other way of reporting unhandled exceptions (obligatory employer plug: SmartAssembly reports an application’s unhandled exceptions straight to you, along with the entire state of the stack and variables at that point). If not, you have to try and replicate it yourself, or do some psychic debugging to try and figure out what’s wrong. However, it’s good that the program crashed. Or, more precisely, it is correct behaviour. An unhandled exception in your application means that, somewhere in your code, there is an assumption that you made that is actually invalid. Coding assumptions Let me explain a bit more. Every method, every line of code you write, depends on implicit assumptions that you have made. Take this following simple method, that copies a collection to an array and includes an item if it isn’t in the collection already, using a supplied IEqualityComparer: public static T[] ToArrayWithItem( ICollection<T> coll, T obj, IEqualityComparer<T> comparer) { // check if the object is in collection already // using the supplied comparer foreach (var item in coll) { if (comparer.Equals(item, obj)) { // it's in the collection already // simply copy the collection to an array // and return it T[] array = new T[coll.Count]; coll.CopyTo(array, 0); return array; } } // not in the collection // copy coll to an array, and add obj to it // then return it T[] array = new T[coll.Count+1]; coll.CopyTo(array, 0); array[array.Length-1] = obj; return array; } What’s all the assumptions made by this fairly simple bit of code? coll is never null comparer is never null coll.CopyTo(array, 0) will copy all the items in the collection into the array, in the order defined for the collection, starting at the first item in the array. The enumerator for coll returns all the items in the collection, in the order defined for the collection comparer.Equals returns true if the items are equal (for whatever definition of ‘equal’ the comparer uses), false otherwise comparer.Equals, coll.CopyTo, and the coll enumerator will never throw an exception or hang for any possible input and any possible values of T coll will have less than 4 billion items in it (this is a built-in limit of the CLR) array won’t be more than 2GB, both on 32 and 64-bit systems, for any possible values of T (again, a limit of the CLR) There are no threads that will modify coll while this method is running and, more esoterically: The C# compiler will compile this code to IL according to the C# specification The CLR and JIT compiler will produce machine code to execute the IL on the user’s computer The computer will execute the machine code correctly That’s a lot of assumptions. Now, it could be that all these assumptions are valid for the situations this method is called. But if this does crash out with an exception, or crash later on, then that shows one of the assumptions has been invalidated somehow. An unhandled exception shows that your code is running in a situation which you did not anticipate, and there is something about how your code runs that you do not understand. Debugging the problem is the process of learning more about the new situation and how your code interacts with it. When you understand the problem, the solution is (usually) obvious. The solution may be a one-line fix, the rewrite of a method or class, or a large-scale refactoring of the codebase, but whatever it is, the fix for the crash will incorporate the new information you’ve gained about your own code, along with the modified assumptions. When code is running with an assumption or invariant it depended on broken, then the result is ‘undefined behaviour’. Anything can happen, up to and including formatting the entire disk or making the user’s computer sentient and start doing a good impression of Skynet. You might think that those can’t happen, but at Halting problem levels of generality, as soon as an assumption the code depended on is broken, the program can do anything. That is why it’s important to fail-fast and stop the program as soon as an invariant is broken, to minimise the damage that is done. What does this mean in practice? To start with, document and check your assumptions. As with most things, there is a level of judgement required. How you check and document your assumptions depends on how the code is used (that’s some more assumptions you’ve made), how likely it is a method will be passed invalid arguments or called in an invalid state, how likely it is the assumptions will be broken, how expensive it is to check the assumptions, and how bad things are likely to get if the assumptions are broken. Now, some assumptions you can assume unless proven otherwise. You can safely assume the C# compiler, CLR, and computer all run the method correctly, unless you have evidence of a compiler, CLR or processor bug. You can also assume that interface implementations work the way you expect them to; implementing an interface is more than simply declaring methods with certain signatures in your type. The behaviour of those methods, and how they work, is part of the interface contract as well. For example, for members of a public API, it is very important to document your assumptions and check your state before running the bulk of the method, throwing ArgumentException, ArgumentNullException, InvalidOperationException, or another exception type as appropriate if the input or state is wrong. For internal and private methods, it is less important. If a private method expects collection items in a certain order, then you don’t necessarily need to explicitly check it in code, but you can add comments or documentation specifying what state you expect the collection to be in at a certain point. That way, anyone debugging your code can immediately see what’s wrong if this does ever become an issue. You can also use DEBUG preprocessor blocks and Debug.Assert to document and check your assumptions without incurring a performance hit in release builds. On my coding soapbox… A few pet peeves of mine around assumptions. Firstly, catch-all try blocks: try { ... } catch { } A catch-all hides exceptions generated by broken assumptions, and lets the program carry on in an unknown state. Later, an exception is likely to be generated due to further broken assumptions due to the unknown state, causing difficulties when debugging as the catch-all has hidden the original problem. It’s much better to let the program crash straight away, so you know where the problem is. You should only use a catch-all if you are sure that any exception generated in the try block is safe to ignore. That’s a pretty big ask! Secondly, using as when you should be casting. Doing this: (obj as IFoo).Method(); or this: IFoo foo = obj as IFoo; ... foo.Method(); when you should be doing this: ((IFoo)obj).Method(); or this: IFoo foo = (IFoo)obj; ... foo.Method(); There’s an assumption here that obj will always implement IFoo. If it doesn’t, then by using as instead of a cast you’ve turned an obvious InvalidCastException at the point of the cast that will probably tell you what type obj actually is, into a non-obvious NullReferenceException at some later point that gives you no information at all. If you believe obj is always an IFoo, then say so in code! Let it fail-fast if not, then it’s far easier to figure out what’s wrong. Thirdly, document your assumptions. If an algorithm depends on a non-trivial relationship between several objects or variables, then say so. A single-line comment will do. Don’t leave it up to whoever’s debugging your code after you to figure it out. Conclusion It’s better to crash out and fail-fast when an assumption is broken. If it doesn’t, then there’s likely to be further crashes along the way that hide the original problem. Or, even worse, your program will be running in an undefined state, where anything can happen. Unhandled exceptions aren’t good per-se, but they give you some very useful information about your code that you didn’t know before. And that can only be a good thing.

  Read the article

• The best way to structure/design game code

  - by Edward

  My question is quite broad and related to the 2D game code design/architecture/structure. Usually the main game consists of the main loop where you update & render your world states. However, it's recommended for many purposes to separate rendering from the game-logic and so on. I am kinda confused about the whole situation. Many game engines/libs/sdks don't follow separation schema. They propagate a way where you define some scenes/stages and they contain some objects and the scene/stage controls the user input and so on. For example, in cocos2d(-x) and libgdx (stage2d) the games are usually done the way that the update logic happens at the same time/place as rendering. Also, the propagated way is to have a structure where an object knows how to draw itself - which is not a separation of updating & rendering. The same with Flash based games, they are usually done the way when an object (class) contains a swf or a texture and some data and holds some update logic itself, or updated from main Scene. And again this object already knows how to draw itself via "addChild". Also, some people recommend to use MVC pattern, which will require to completely obey the structure of those engines/libs/sdks. Maybe I am overthinking everything, but I am totally confused. I would be grateful if somebody could point me to a correct direction with the game code structures. What is your way of doing things in libgdx/cocos2d/flash?

  Read the article

• Automatically wake up notebooks not on the ethernet

  - by gletscher

  I am looking for an automated backup system and I like bacula. I have 3 Notebooks and a Desktop computer that need regular backup. Now I don't want to let them run all night just to do the backuping, so I was thinking I could use wake-on-lan to have bacula wake up the machines, then do the backups, and shut them down afterswards. While this may work with devices on the ethernet, it won't work with the Notebooks on the wifi. So is it possible to have the Notebooks schedules to automatically wake up from suspend or shutdown ? Or is it possible to interject a shutdown command if it is after a certain hour and call the bacula director to start the backup now? I'm new to controlling the linux system using scripts, so any hints on how and where to start are greatly appreciated. Thanks alot for your help, input and ideas.

  Read the article

• How can I strip down Ubuntu?

  - by Thomas Owens

  I'm trying to fix what I consider a bloated install of Ubuntu. When I install Ubuntu on a machine, I get things that I don't want - web browsers, office applications, media players, accessibility utilities, Ubuntu One, and so on. My goal is to create a way that I can have an install of Ubuntu that contains only the most minimal packages - the administrative tools and package manager, a GUI (my preference would be GNOME), a text editor, core drivers (video cards, network cards - wired and wireless, input devices), and anything else that I have to have to run a stable distribution. From there, I would like to pick and choose which packages I install to create my own customized system. After playing around with other distros like Arch and Slackware, like how they provide a barebones install by default. However, I get trapped in a "configuration hell" - right now, I tried moving away from Ubuntu and to Arch, but after spending 6 hours with it, I still don't have a usable system. It's half configured and I don't have any usable software packages to enable me to work. Is anything that can help me available? Either something like the OpenSUSE builder that lets you choose applications and packages for the CD, an advanced installation mode where I can choose the packages to install and which to ignore, or a guide on how to strip Ubuntu down to its bare bones? And I suppose a natural follow up to this is once I have a stripped down Ubuntu, will this affect updating at all? When Canonical releases the next version of Ubuntu, I don't want any bloatware reinstalled. And yes, most of the applications that come with Ubuntu, I simply don't use. Ever.

  Read the article

• DC on Hyper V Host

  - by Saif Khan

  I've read a few similar questions but wasn't clear. I have a small office (13) users and recently purchased a new single server (this is all I have to work with for now). Server specs Memory - 16GB Drives - 6 SCSI (2TB) PROCESSOR - DUAL QUAD I plan on making the Hyper-V host the DC and then 2 VMs, one for a file server and the other an application server. Question - since I am restricted to this single server, would it be a big issue making the Hyper-V host the domain controller? Your input greatly appreciated.

  Read the article

• Using optimization to assign by preference

  - by Aarthi

  I have 100 objects ("candies") that I need to distribute between five people so that each has an equal number of candies (in this case, 20 candies per person). However, each person has also expressed their preferences of candy to me in a chart, similar to below. Top-favored candies receive 10 points, least-favored candies receive -10 points, and neutral-favored candies receive 0.5 points. I need to sort the items out so that: Each person receives the same number of candies Each person's total "satisfaction" (points) is maximized My output is a list of each person's assigned items I'm familiar with Excel's in-house Monte Carlo simulation tools (Solver, F9 diceroll, etc) and would like to stick to those tools. While I know how to set up the chart, and how to use the column summation to input into Solver, I don't know how to get it to give me the desired output. Furthermore, how do I adjust the solver so it takes into account individual preferences rather than empirical ones? To wit: how do I begin setting up this model?

  Read the article

• What resources are there for creating a dedicated NES emulator box?

  - by normalocity

  Where do I start, and what communities should I get involved in, in order to achieve the following? Ideally, I'd like to have a box that does the following (doesn't have to do this out of the box, I'm just looking to be able to achieve these goals through configs and necessary dependencies): Either bypasses login, or auto login Auto-start FCEUX with options that will (a) automatically start a ROM of my choosing, and (b) go into full-screen mode. You can assume that before I get that far, I've already configured the input devices and video options. I'd like to create (or install, if it exists) a full-screen app that takes a list of ROMs, allows me to select one with a gamepad/arcade stick, and press a button to open that game Be able to map a button on a gamepad/arcade stick to the "Power off" or exit function of the emulator, such that it will take me back to the ROM selection screen. I've already successfully installed FCEUX and tested it with an arcade stick I own, so I'm not looking for an emulator installer guide. I don't know if the ROM selector app exists already, but I'm a Java developer, and could probably create one (so long as it's not too difficult to support controllers - I was thinking of using Slick2D for this - a gaming library that I'm already pretty familiar with). The goal would be a dedicated box that I have connected to my TV. I power it on. It boots up and starts the ROM selection app, which passes the proper parameters to FCEUX (or another emulator that I might switch to at a later time), and I'm ready to go. Basically an NES emulator as a real, living room console. Also, as far as mapping a controller button to functions in the app, well, I've also played around with hardware, and it would be pretty trivial for me to modify a gamepad to trigger key presses. I just don't want to go to that length if it's not necessary.

  Read the article

• Algorithm to shift the car

  - by Simran kaur

  I have a track that can be divided into n number of tracks and a car as GamObject. The track has transforms such that some part of the track's width lies in negative x axis and other in positive. Requirement: One move should cross one track. On every move(left or right), I want the car to reach exact centre of the next track on either sides i.e left or right. My code: Problem: : Because of negative values , somewhere I am missing out something that is making car move not in desirable positions and that's because of negative values only. variable tracks is the number of tracks the whole track is divided in. variable dist is the total width of the complete track. On left movement: if (Input.GetKeyDown (KeyCode.LeftArrow)) { if (this.transform.position.x < r.renderer.bounds.min.x + box.size.x) { this.transform.position = new Vector3 (r.renderer.bounds.min.x + Mathf.FloorToInt(box.size.x), this.transform.position.y, this.transform.position.z); } else { int tracknumber = Mathf.RoundToInt(dist - transform.position.x)/tracks; float averagedistance = (tracknumber*(dist/tracks) + (tracknumber-1)*(dist/tracks))/2; if(transform.position.x > averagedistoftracks) { amountofmovement = amountofmovement + (transform.position.x - averagedistance); } else { amountofmovement = amountofmovement - (averagedistance - transform.position.x); } this.transform.position = new Vector3 (this.transform.position.x - amountofmovement, this.transform.position.y, this.transform.position.z); } }

  Read the article

• Blur gets displaced compared to original image

  - by user1294203

  I have implemented a SSAO and I'm using a blur step to smooth it out. The problem is that the blurred texture is slightly displaced compared to the original. I'm blurring using a 4x4 kernel since that was my noise kernel in SSAO. The following is the blurring shader: float result = 0.0; for(int i = 0; i < 4; i++){ for(int j = 0; j < 4; j++){ vec2 offset = vec2(TEXEL_SIZE.x * i, TEXEL_SIZE.y * j); result += texture(aoSampler, TexCoord + offset).r; } } out_AO = vec4(vec3(0.0), result * 0.0625); Where TEXEL_SIZE is one over my window resolution. I was thinking that this is was an error based on how OpenGL counts the Texel center, so I tried displacing the texture coordinate I was using by 0.5 * TEXEL_SIZE, but there was still a slight displacement. The texture input to my blur shader, has wrap parameters: glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP); When I tell the blur shader to just output the the value of the pixel, the result is not displaced, so it must have something to do with how neighboring pixels are sampled. Any thoughts?

  Read the article

• Language parsing to find important words

  - by Matt Huggins

  I'm looking for some input and theory on how to approach a lexical topic. Let's say I have a collection of strings, which may just be one sentence or potentially multiple sentences. I'd like to parse these strings to and rip out the most important words, perhaps with a score that denotes how likely the word is to be important. Let's look at a few examples of what I mean. Example #1: "I really want a Keurig, but I can't afford one!" This is a very basic example, just one sentence. As a human, I can easily see that "Keurig" is the most important word here. Also, "afford" is relatively important, though it's clearly not the primary point of the sentence. The word "I" appears twice, but it is not important at all since it doesn't really tell us any information. I might expect to see a hash of word/scores something like this: "Keurig" => 0.9 "afford" => 0.4 "want" => 0.2 "really" => 0.1 etc... Example #2: "Just had one of the best swimming practices of my life. Hopefully I can maintain my times come the competition. If only I had remembered to take of my non-waterproof watch." This example has multiple sentences, so there will be more important words throughout. Without repeating the point exercise from example #1, I would probably expect to see two or three really important words come out of this: "swimming" (or "swimming practice"), "competition", & "watch" (or "waterproof watch" or "non-waterproof watch" depending on how the hyphen is handled). Given a couple examples like this, how would you go about doing something similar? Are there any existing (open source) libraries or algorithms in programming that already do this?

  Read the article

• Show which modifier keys are pressed during screen recording?

  - by Jenko

  I'd like to see which modifier keys I've pressed during screen recordings so my students can understand what keys I've pressed while I click and drag. Is there any software that can do this? I'm aware that Windows 7 does this internally, if there's a way to enable it. Windows 7 When you have a Wacom tablet connected to your PC, or if you have a Tablet PC, windows shows little yellow tip bubbles whenever you press modifier keys. Any way to enable these on a normal PC? Update: I've tried starting the Tablet PC Input Service but nothing happens. The Tablet PC Settings dialog has nothing interesting either. Is there a registry setting I can tweak?

  Read the article

• Netcat I/O enhancements

  - by user13277689

  When Netcat integrated into OpenSolaris it was already clear that there will be couple of enhancements needed. The biggest set of the changes made after Solaris 11 Express was released brings various I/O enhancements to netcat shipped with Solaris 11. Also, since Solaris 11, the netcat package is installed by default in all distribution forms (live CD, text install, ...). Now, let's take a look at the new functionality: /usr/bin/netcat alternative program name (symlink) -b bufsize I/O buffer size -E use exclusive bind for the listening socket -e program program to execute -F no network close upon EOF on stdin -i timeout extension of timeout specification -L timeout linger on close timeout -l -p port addr previously not allowed usage -m byte_count Quit after receiving byte_count bytes -N file pattern for UDP scanning -I bufsize size of input socket buffer -O bufsize size of output socket buffer -R redir_spec port redirection addr/port[/{tcp,udp}] syntax of redir_spec -Z bypass zone boundaries -q timeout timeout after EOF on stdin Obviously, the Swiss army knife of networking tools just got a bit thicker. While by themselves the options are pretty self explanatory, their combination together with other options, context of use or boundary values of option arguments make it possible to construct small but powerful tools. For example: the port redirector allows to convert TCP stream to UDP datagrams. the buffer size specification makes it possible to send one byte TCP segments or to produce IP fragments easily. the socket linger option can be used to produce TCP RST segments by setting the timeout to 0 execute option makes it possible to simulate TCP/UDP servers or clients with shell/python/Perl/whatever script etc. If you find some other helpful ways use please share via comments. Manual page nc(1) contains more details, along with examples on how to use some of these new options.

  Read the article

• beginner - best way to do a 'Confirm' page? [closed]

  - by W_P

  I am a beginning web app developer, wondering about the best way to implement a "Confirm Page" upon form submission. I have heard that it's best for the script that a form POSTs to to be implemented by handling the POST data and then redirecting to another page, so the user isn't directly viewing the page that was POSTed to. My question is about the best way to implement a "Confirm before data save" page. Do I Have my form POST to a script, which marshals the data, puts in a GET, and redirects to the confirm page, which unmarshals and displays the data in another form, where the user can then either confirm (which causes another POST to a script that actually saves the data) or deny (which causes the user to be redirected back to the original form, with their input added)? Have my form POST directly to the confirm page, which is displayed to the user and then, like #1, gives the user the option to confirm or deny? Have my form GET the confirm page, which then does the expected behavior? I feel like there is a common-sense answer to this question that I am just not getting.

  Read the article

< Previous Page | 407 408 409 410 411 412 413 414 415 416 417 418  | Next Page >