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• Can’t connect to SQL Server 2008 - looks like Shared Memory problem

  - by user38556

  I am unable to connect to my local instance of SQL Server 2008 Express using SQL Server Management Studio. I believe the problem is related to a change I made to the connection protocols. Before the error occurred, I had Shared Memory enabled and Named Pipes and TCP/IP disabled. I then enabled both Named Pipes and TCP/IP, and this is when I started experiencing the problem. When I try to connect to the server with SSMS (with either my SQL server sysadmin login or with windows authentication), I get the following error message: A connection was successfully established with the server, but then an error occurred during the login process. (provider: Named Pipes Provider, error: 0 - No process is on the other end of the pipe.) (Microsoft SQL Server, Error: 233) Why is it returning a Named Pipes error? Why would it not just use Shared Memory, as this has a higher priority order in the list of connection protocols? It seems like it is not listening on Shared Memory for some reason? When I set Named Pipes to enabled and try to connect, I get the same error message. My windows account is does not have administrator priviliges on my computer - perhaps this is making a difference in some way (as some of the discussions in this post about an "SuperSocketNetLib\Lpc" registry key seems to suggest). I have tried restarting the SQL Server service, by the way, and also tried to get someone to log onto the machine with an admin account to restart the SQL Server service. Still no luck.

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• How to kill unkillable Python-processes running as root

  - by Andrei

  I am experiencing an annoying problem with sshuttle running it on 10.7.3, MBA with the latest firmware update -- after I stop it (ctrl+c twice), or loose connection, or close the lid, I cannot restore it until I restart the system. The restarting takes notably more time, than it would normally take. I have tried to flush ipfw rules - not helping. Could you advice me how to restore sshuttle connection (without restarting os)? The following processes remain running as root, which I do not know how to kill (tried sudo kill -9 <pid> with no luck): root 14464 python ./main.py python -v -v --firewall 12296 12296 root 14396 python ./main.py python -v -v --firewall 12297 12297 root 14306 python ./main.py python -v -v --firewall 12298 12298 root 3678 python ./main.py python -v -v --firewall 12299 12299 root 2263 python ./main.py python -v -v --firewall 12300 12300 The command I use to run proxy: ./sshuttle --dns -r [email protected] 10.0.0.0/8 -vv The last message I get trying to restore the connection: ... firewall manager: starting transproxy. s: Ready: 1 r=[4] w=[] x=[] s: < channel=0 cmd=PING len=7 s: > channel=0 cmd=PONG len=7 (fullness=554) s: mux wrote: 15/15 s: Waiting: 1 r=[4] w=[] x=[] (fullness=561/0) >> ipfw -q add 12300 check-state ip from any to any >> ipfw -q add 12300 skipto 12301 tcp from any to 127.0.0.0/8 >> ipfw -q add 12300 fwd 127.0.0.1,12300 tcp from any to 10.0.0.0/8 not ipttl 42 keep-state setup >> ipfw -q add 12300 divert 12300 udp from any to 10.0.1.1/32 53 not ipttl 42 >> ipfw -q add 12300 divert 12300 udp from any 12300 to any not ipttl 42 Update: $ ps -ax|grep python 1611 ?? 0:06.49 python ./main.py python -v -v --firewall 12300 12300 48844 ?? 0:00.05 python ./main.py python -v -v --firewall 12299 12299 49538 ttys000 0:00.00 grep python

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• what port should I open for mysql master-master replication?

  - by Vanddel

  I have two servers running php5-fpm and a load balancer running nginx, the three servers share /var/www/drupal using nfs. nfs is working correctly. I replicated the two servers' database using mysql master master replication. everything was working fine till I added my iptables rules. In my iptables script, I first drop all chains then I accept the ones I want, other than that there are no other drop statements. I opened port 3306 for mysql replication like this : (the rule is on both servers ) iptables -A INPUT -p tcp -s $ip_Of_Other_Server --dport 3306 -j ACCEPT iptables -A OUTPUT -p tcp -d $ip_Of_Other_Server --sport 3306 -j ACCEPT The problem is, when I run both servers and I try to log in using my account on drupal it doesn't log in although I find a successful log in attempt in drupal logs. When I run only one server of them I can log in normally. when I allow everything in my iptables rules it works normally. I believe there's some port I need to open using iptables for the replication to work correctly but I can't find which one to open.

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• Correctly setting up UFW on Ubuntu Server 10 LTS which has Nginx, FastCGI and MySQL?

  - by littlejim84

  I'm wanting to get my firewall on my new webserver to be as secure as it needs to be. After I did research for iptables, I came across UFW (Uncomplicated FireWall). This looks like a better way for me to setup a firewall on Ubuntu Server 10 LTS and seeing that it's part of the install, it seems to make sense. My server will have Nginx, FastCGI and MySQL on it. I also want to be allow SSH access (obviously). So I'm curious to know exactly how I should set up UFW and is there anything else I need to take into consideration? After doing research, I found an article that explains it this way: # turn on ufw ufw enable # log all activity (you'll be glad you have this later) ufw logging on # allow port 80 for tcp (web stuff) ufw allow 80/tcp # allow our ssh port ufw allow 5555 # deny everything else ufw default deny # open the ssh config file and edit the port number from 22 to 5555, ctrl-x to exit nano /etc/ssh/sshd_config # restart ssh (don't forget to ssh with port 5555, not 22 from now on) /etc/init.d/ssh reload This all seems to make sense to me. But is it all correct? I want to back this up with any other opinions or advice to ensure I do this right on my server. Many thanks!

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• Process killing trouble

  - by Aditya Singh

  I am trying to program a server software which involves a lot of testing on java / scala platform. Whenever i compile and execute the code. It starts listening on port 80. Sometimes i need to terminate it by Ctrl+C when it hangs. In that case, ubuntu is not freeing the port. So in order to run the process, i have to restart the machine. I see this at ps aux root 1924 0.0 0.0 5796 1660 pts/0 T 05:44 0:00 sudo scala - root 1925 0.2 1.5 491448 40796 pts/0 Tl 05:44 0:03 java -Xmx256M -Xms16M So process 1924 and 1925. I did sudo kill on both these. But then they keep on persisting even after a long time. sudo nmap -T Aggressive -A -v 127.0.0.1 -p 1-65000 Scanning localhost (127.0.0.1) [65000 ports] Discovered open port 80/tcp on 127.0.0.1 It means its still there ! sudo netstat --tcp --udp --listening --program tcp6 0 0 [::]:www [::]:* LISTEN 1925/java tcp6 0 0 ip6-localhost:ipp [::]:* LISTEN 1185/cupsd This means its 1925 - java How to kill it.

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• can't Remote desktop to windows XP, blaming the server side

  - by Jin

  After rebooting my work PC (windows XP sp3) this Wednesday (thank to Microsoft Tuesday), I found that I can't remote desktop to my work PC from home (with VPN to company). I have been remote-desktop to work for years and I am really surprised since connectivity is not the problem, so I brought up wireshark to sniff the packets. I can see after TCP handshake, client sent X.224 Connection Request 03 00 00 13 0e e0 00 00 00 00 00 01 00 08 00 03 00 00 00 server sent X.224 Connection Confirm. 03 00 00 0b 06 d0 00 00 12 34 00 According to "MS-RDPBCGR", the official spec on RDP, the server should include Negotiation Response in the "Connection Confirm" message but it didn't. It's empty. I googled a lot but didn't find any clue on why server did that. By the way, I used the same remote desktop client and can connect to other windows XP PC. Here are a couple of pieces of information that may help to give a clue: Since TCP handshake (server port being 3389), I believe the svchost service is actually running. going to control panel -- system window, --- "Remote" tab, the remote desktop is indeeded checked and it states that my username is allowed. according to the packet capture, client didn't even get a chance to tell server what user was trying to logon. Yes, the progress bar showed up a few seconds and then it went back to the "Remote desktop Connection" window again. Searched "windowsupdate.log", didn't find any appearance of the word "remote".

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• Linux Experts Riddle: Network output of 10MB/s on 10GB/s NIC

  - by user150324

  I have two CentOS 6 servers. I am trying to transfer files between them. Source server has 10GB/s NIC nd destination server has 1GB/s NIC. Regardless to the command used nor the protocol, the transfer speed is ~1 Mega byte per second. The goal is at least couple dozens MB per second. I have tried: rsync (also with various encryptions), scp, wget, aftp, nc. Here's some testing results with iperf: [root@serv ~]# iperf -c XXX.XXX.XXX.XXX -i 1 ------------------------------------------------------------ Client connecting to XXX.XXX.XXX.XXX, TCP port 5001 TCP window size: 64.0 KByte (default) ------------------------------------------------------------ [ 3] local XXX.XXX.XXX.XXX port 33180 connected with XXX.XXX.XXX.XXX port 5001 [ ID] Interval Transfer Bandwidth [ 3] 0.0- 1.0 sec 1.30 MBytes 10.9 Mbits/sec [ ID] Interval Transfer Bandwidth [ 3] 1.0- 2.0 sec 1.28 MBytes 10.7 Mbits/sec [ ID] Interval Transfer Bandwidth [ 3] 2.0- 3.0 sec 1.34 MBytes 11.3 Mbits/sec [ ID] Interval Transfer Bandwidth [ 3] 3.0- 4.0 sec 1.53 MBytes 12.8 Mbits/sec [ ID] Interval Transfer Bandwidth [ 3] 4.0- 5.0 sec 1.65 MBytes 13.8 Mbits/sec [ ID] Interval Transfer Bandwidth [ 3] 5.0- 6.0 sec 1.79 MBytes 15.0 Mbits/sec [ ID] Interval Transfer Bandwidth [ 3] 6.0- 7.0 sec 1.95 MBytes 16.3 Mbits/sec [ ID] Interval Transfer Bandwidth [ 3] 7.0- 8.0 sec 1.98 MBytes 16.6 Mbits/sec [ ID] Interval Transfer Bandwidth [ 3] 8.0- 9.0 sec 1.91 MBytes 16.0 Mbits/sec [ ID] Interval Transfer Bandwidth [ 3] 9.0-10.0 sec 2.05 MBytes 17.2 Mbits/sec [ ID] Interval Transfer Bandwidth [ 3] 0.0-10.0 sec 1.68 MBytes 14.0 Mbits/sec I guess HD is not the bottleneck here.

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• New AD-DC in a new Site is refusing cross-site IPv4 connections

  - by sysadmin1138

  We just added a new Server 2008 (sp2) Domain Controller in a new Site, our first such config. It's over a VPN gateway WAN (10Mbit). Unfortunately it is displaying a strange network symptom. Connections to the SMB ports (TCP/139 and TCP/445) are being actively refused... if the connection is coming in on pure IPv4. If the incoming connection is coming by way of the 6to4 tunnel those connections establish and work just fine. It isn't the Firewall, since this behavior can be replicated with the firewall turned off. Also, it's actually issuing RST packets to connection attempts; something that only happens with a Windows Firewall if there is a service behind a port and the service itself denies access. I doubt it's some firewall device on the wire, since the server this one replaced was running Samba and access to it from our main network functioned just fine. I'm thinking it might have something to do with the Subnet lists in AD Sites & Services, but I'm not sure. We haven't put any IPv6 addresses in there, just v4, and it's the v4 connections that are being denied. Unfortunately, I can't figure this out. We need to be able to talk to this DC from the main campus. Is there some kind of site-based SMB-level filtering going on? I can talk to the DC's on campus just fine, but that's over that v6 tunnel. I don't have access to a regular machine on that remote subnet, which limits my ability to test.

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• Remote desktop connection to network printer

  - by andand

  I'm trying to print a document from a remote WinXP machine to a network printer I use on a local Win7 machine using Remote Desktop. The network printer does not appear in the list of those available on the WinXP box. In more detail, the local machine runs Windows 7 (no admin rights) and connects to a network printer managed by a print server (i.e. not using a local TCP/IP Port). I have access to a Windows XP host on a separate network which I access using Remote Desktop. I would like to have print requests from the remote XP box forwarded to the network printer I use on the Windows 7 machine. The XP machine cannot access the print server I use on the Win7 machine nor can it create a TCP/IP port to connect directly to the printer (network configuration issues). After having consulting the KB312135 I confirmed the "Printers" option was selected in the Remote Desktop Client, Local Resources Tab, yet the network printer does not appear on the list of available printers on the XP box. Is this a lost cause or is there something else I haven't managed to locate yet?

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• Connecting to MySQL Server from PHP Command Line (MAMP)

  - by Austin White

  First of all, I'm using Mac OSX 1.6, MAMP 1.9, PHP 5.3.4, and MySQL 5.1.44. I'm in the process of setting up a video encoding service for a site using Chris Boulton's PHP-Resque and Redis. Once the worker process is fired and the videos have been encoded, I need to save their locations to a mysql database. The php script is being run from the shell, so that is where the issue begins. I import the mysql settings and when it attempts to connect, I get the following errors: Warning: mysqli::mysqli(): php_network_getaddresses: getaddrinfo failed: nodename nor servname provided, or not known in /Users/austingym/Documents/Dropbox/Website/htdocs/homefree/lib/MySQLi_Extended.class.php on line 24 Warning: mysqli::mysqli(): [2002] php_network_getaddresses: getaddrinfo failed: nodename nor servn (trying to connect via tcp://MYSQL_SERVER:3306) in /Users/austingym/Documents/Dropbox/Website/htdocs/homefree/lib/MySQLi_Extended.class.php on line 24 Warning: mysqli::mysqli(): (HY000/2002): php_network_getaddresses: getaddrinfo failed: nodename nor servname provided, or not known in /Users/austingym/Documents/Dropbox/Website/htdocs/homefree/lib/MySQLi_Extended.class.php on line 24 Warning: mysqli::set_charset(): Couldn't fetch MySQLi_Extended in /Users/austingym/Documents/Dropbox/Website/htdocs/homefree/lib/MySQLi_Extended.class.php on line 32 I realize that the error is occurring because it's trying to connect to tcp://MYSQL_SERVER:3306, when MySQL is on port 8889. I've been reading about Mac OSX and MAMP errors regarding the mysql.sock and I've gone through multiple forums and tried various fixes, but none have worked. I've tried PATH=/Applications/MAMP/Library/bin/:/Applications/MAMP/bin/php5.3/bin/:/opt/local/bin:/opt/local/sbin:$PATH and sudo ln -s /Applications/MAMP/tmp/mysql/mysql.sock /tmp/mysql.sock but neither have worked. I even ran a search on my machine for "3306" to find where it's being set, but because that's the normal default, I'm guessing it's not being set explicitly. Any clues on how to fix this rather challenging error?

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• Can OpenVPN invoke DHCP Client?

  - by Ency

  I have got working VPN connection through openvpn, but I would like to use also my DHCP server and not openvpn's push feature. Currently everything works fine, but I have to manually start dhcp client, eg. dhclient tap0 and I get IP and other important stuff from my DHCP, is there any directive which start DHCP Client when connection is established? There is my client's config: remote there.is.server.com float dev tap tls-client #pull port 1194 proto tcp-client persist-tun dev tap0 #ifconfig 192.168.69.201 255.255.255.0 #route-up "dhclient tap0" #dhcp-renew ifconfig 0.0.0.0 255.255.255.0 ifconfig-noexec ifconfig-nowarn ca /etc/openvpn/ca.crt cert /etc/openvpn/encyNtb_openvpn_client.crt key /etc/openvpn/encyNtb_openvpn_client.key dh /etc/openvpn/dh-openvpn.dh ping 10 ping-restart 120 comp-lzo verb 5 log-append /var/log/openvpn.log Here comes server's config: mode server tls-server dev tap0 local servers.ip.here port 1194 proto tcp-server server-bridge # Allow comunication between clients client-to-client # Allowing duplicate users per one certificate duplicate-cn # CA Certificate, VPN Server Certificate, key, DH and Revocation list ca /etc/ssl/CA/certs/ca.crt cert /etc/ssl/CA/certs/openvpn_server.crt key /etc/ssl/CA/private/openvpn_server.key dh /etc/ssl/CA/dh/dh-openvpn.dh crl-verify /etc/ssl/CA/crl.pem # When no response is recieved within 120seconds, client is disconected keepalive 10 60 persist-tun persist-key user openvpn group openvpn # Log and Connected clients file log-append /var/log/openvpn verb 3 status /var/run/openvpn/vpn.status 10 # Compression comp-lzo #Push data to client push "route-gateway 192.168.69.1" push "redirect-gateway def1"

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• Windows 7 network performance tuning for LAN

  - by Hubert Kario

  I want to tune Windows 7 TCP stack for speed in a LAN environment. Bit of background info: I've got a Citrix XenServer set up with Windows 2008R2, Windows 7 and Debian Lenny with Citrix kernel, Windows machines have Tools installed the iperf server process is running on different host, also Debian Lenny. The servers are otherwise idle, tests were repeated few times to confirm results. While testing with iperf 2008R2 can achieve around 600-700Mbps with no tuning what so ever but I can't find any guide or set of parameters that will make Windows 7 achieve anything over 150Mbps with no change in TCP window size using -w parameter to iperf. I tried using netsh autotuining to disabled, experimental, normal and highlyrestricted - no change. Changing congestionprovider doesn't do anything, just as rss and chimney. Setting all the available settings to same values as on Windows 2008R2 host doesn't help. To summarize: Windows 2008R2 default settings: 600-700Mbps Debian, default settings: 600Mbps Windows 7 default settings: 120Mbps Windows 7 default, iperf -w 65536: 400-500Mbps While the missing 400Mbps in performance I blame on crappy Realtek NIC in the XenServer host (I can do ~980Mbps from my laptop to the iperf server) it doesn't explain why Windows 7 can't achieve good performance without manually tuning window size at the application level. So, how to tune Windows 7?

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• Which ports are needed for NTLM (Windows Authentication) to connect to SQL Server?

  - by Adam Bellaire

  I've got SQL server running on a machine which is not in a domain, and which is not operating in mixed mode (it's running with "Windows Authentication"). I'm trying to connect to it from a Linux web server running freetds via TCP/IP, using NTLM to authenticate. The firewall on the SQL server is very restrictive. 1433 is open to my web server, but I'm getting conflicting information from the web on what additional ports (TCP/UDP) are needed for NTLM to succeed. It is currently fail; I can talk on 1433 to request NTLM, but the actual authentication always fails. One source says 137, 138, 139, but those are just the NetBIOS ports. Do I really need those? Another source says 135. Still others seem to say 1434... I can't make heads or tails of it. Dammit Jim, I'm a programmer, not a network administrator! EDIT: The exact error message: Msg 18452, Level 14, State 1, Server , Line 0 Login failed for user '(null)'. Reason: Not associated with a trusted SQL Server connection. Msg 20002, Level 9, State -1, Server OpenClient, Line -1 Adaptive Server connection failed I am attempting to connect with a remote machine username, i.e. 'servername\username'. Some sources recommend that I set up mirrored accounts on the local and remote machines, but the local machine is running Linux, not IIS under Windows.

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• Dante (SOCKS server) not working

  - by gregmac

  I'm trying to set up a SOCKS proxy using dante for testing purposes. However, I can't even get it to work with a web browser, after looking at several tutorials on how to do that. I've tried in both IE and Firefox, in both cases, using "Manual proxy configuration", leave everything blank except for SOCKS host, and then put in the IP of my proxy and the port number (1080). I just get "Server not found" / "Problems loading this page" and don't see anything in danted, even running in debug mode. If I do a "telnet 10.0.0.40 1080" I do see the connection open in danted debug output, so I know that much is working. Here's my config: logoutput: stdout /var/log/danted/danted.log internal: eth0 port = 1080 external: eth0 method: username none #rfc931 user.privileged: proxy user.notprivileged: nobody user.libwrap: nobody connecttimeout: 30 # on a lan, this should be enough if method is "none". client pass { from: 10.0.0.0/8 port 1-65535 to: 0.0.0.0/0 } client pass { from: 127.0.0.0/8 port 1-65535 to: 0.0.0.0/0 } client block { from: 0.0.0.0/0 to: 0.0.0.0/0 log: connect error } block { from: 0.0.0.0/0 to: 127.0.0.0/8 log: connect error } pass { from: 10.0.0.0/8 to: 0.0.0.0/0 protocol: tcp udp } pass { from: 127.0.0.0/8 to: 0.0.0.0/0 protocol: tcp udp } block { from: 0.0.0.0/0 to: 0.0.0.0/0 log: connect error } I'm sure I'm probably missing something simple, but I'm lost. I haven't even thought about SOCKS since the late 90's.

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• Rsyslogd not listening on port

  - by amorfis

  I installed rsyslogd on ubuntu server, started it and everything looks fine, but the port the server should listen on is not opened. ubuntu@node7:~$ sudo service rsyslog restart rsyslog stop/waiting rsyslog start/running, process 14114 Netstat shows it is not listening: ubuntu@node7:~$ netstat -tlan Active Internet connections (servers and established) Proto Recv-Q Send-Q Local Address Foreign Address State tcp 0 0 0.0.0.0:22 0.0.0.0:* LISTEN tcp 0 320 172.22.0.17:22 10.8.8.38:61335 ESTABLISHED tcp6 0 0 :::22 :::* LISTEN tcp6 0 0 :::2776 :::* LISTEN tcp6 0 0 :::2777 :::* LISTEN tcp6 0 0 172.22.0.17:2777 172.22.0.11:56554 ESTABLISHED tcp6 0 0 172.22.0.17:2776 172.22.0.11:39780 ESTABLISHED This is how /etc/rsyslog.conf looks like (most comments omitted): ubuntu@node7:~$ cat /etc/rsyslog.conf ################# #### MODULES #### ################# $ModLoad imuxsock # provides support for local system logging $ModLoad imklog # provides kernel logging support (previously done by rklogd) $ModLoad imtcp $InputTCPServerRun 514 ########################### #### GLOBAL DIRECTIVES #### ########################### $ActionFileDefaultTemplate RSYSLOG_TraditionalFileFormat $RepeatedMsgReduction on $WorkDirectory /var/spool/rsyslog $FileOwner syslog $FileGroup adm $FileCreateMode 0640 $DirCreateMode 0755 $Umask 0022 $PrivDropToUser syslog $PrivDropToGroup adm $IncludeConfig /etc/rsyslog.d/*.conf In /etc/rsyslog.d/35-server-per-host.conf I have following lines, and I suspect this can be the cause. What does it mean? # Stop processing of all non-local messages. You can process remote messages # on levels less than 35. :fromhost-ip,!isequal,"127.0.0.1" ~ and if it is, how could I change it to have server listening and receiving and logging messages? UPDATE: I commented out suspected line, but still it's not listening on port 514

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• CryptSvc not matched by Windows 7 Firewall rule

  - by theultramage

  I am using Windows Firewall in conjunction with a third-party tool to get notified about new outbound connection attempts (Windows Firewall Notifier or Windows Firewall Control). The way these tools do it is by setting the firewall to deny by default, and to add an auditing policy to log blocked connections into the Security event log. Then they watch the log, and display notification about newly added entries. netsh advfirewall set allprofiles firewallpolicy blockinbound,blockoutbound auditpol /set /subcategory:{0CCE9226-69AE-11D9-BED3-505054503030} /failure:enable With this configuration in place, I now need to craft outbound allow rules for applications and system services. Here is the rule for CryptSvc, the service frequently used for certificate validation and revocation checking: netsh advfirewall firewall add rule name="Windows Cryptographic Services" action=allow enable=yes profile=any program="%SystemRoot%\system32\svchost.exe" service="CryptSvc" dir=out protocol=tcp remoteport=80,443 The problem is, this rule does not work. Unless I change the scope to "all programs and services" (which is really unhealthy), connection denied events like the following will keep appearing in the security log: Event 5157, Microsoft Windows security auditing. The Windows Filtering Platform has blocked a connection. Application Information: Process ID: 1476 (<- svchost.exe with CryptSvc and nothing else) Application Name: \device\harddiskvolume1\windows\system32\svchost.exe Network Information: Direction: Outbound Source Address: 192.168.0.1 Source Port: 49616 Destination Address: 2.16.52.16 Destination Port: 80 Protocol: 6 (<- TCP) To make sure it's CryptSvc, I have let the connection through and reviewed its traffic; I also configured CryptSvc to run in its own svchost instance to make it more obvious: ;sc config CryptSvc type= share sc config CryptSvc type= own So... why is it not matching the firewall rule, and how to fix that?

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• Throughput; capacity planning help for C10K like design

  - by z8000

  I am designing a network service in which clients connect and stay connected -- the model is not far off from IRC less the s2s connections. I could use some help understanding how to do capacity planning, in particular with the system resource costs associated with handling messages from/to clients. There's an article that tried to get 1 million clients connected to the same server [1]. Of course, most of these clients were completely idle in the test. If the clients sent a message every 5 seconds or so the system would surely be brought to its knees. But... How do you do less hand-waving and you know, measure such a breaking point? We're talking about messages being sent by a client over a TCP socket, into the kernel, and read by an application. The data is shuffled around in memory from one buffer to another. Do I need to consider memory throughput ("5 GT/s" [2], etc.)? I'm pretty sure I have the ability to measure the basic memory requirements due to TCP/IP buffers, expected bandwidth, and CPU resources required to process messages. I'm a little dim on what I'm calling "thoughput". Help! Also, does anyone really do this? Or, do most people sort of hand-wave and see what the real world offers, and then react appropriately? [1] http://www.metabrew.com/article/a-million-user-comet-application-with-mochiweb-part-3/ [2] http://en.wikipedia.org/wiki/GT/s

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• Getting 502 instead of 503 when all backend servers are down running HAProxy behind Apache

  - by scarba05

  I'm testing running HAProxy as a dedicated load balancer behind Apache 2.2, replacing our current configuration where we use Apache's load balancer. In our current, Apache only, set-up if all the backend (origin) servers are down Apache will serve a 503 service unavailable message. With HAProxy I get a 502 bad gateway response. I'm using a simple reverse proxy rewrite rule in Apache RewriteRule ^/(.*) http://127.0.0.1:8000/$1 [last,proxy] In HAProxy I have the following (running in default tcp mode) defaults log global option tcp-smart-accept timeout connect 7s timeout client 60s timeout queue 120s timeout server 60s listen my_server 127.0.0.1:8000 balance leastconn server backend1 127.0.0.1:8001 check observe layer4 maxconn 2 server backend1 127.0.0.1:8001 check observe layer4 maxconn 2 Testing connecting directly to the load balancer when the backend servers are down: [root@dev ~]# wget http://127.0.0.1:8000/ test.html --2012-05-28 11:45:28-- http://127.0.0.1:8000/ Connecting to 127.0.0.1:8000... connected. HTTP request sent, awaiting response... No data received. So presumably this is down to the fact that HAProxy accepts the connection and then closes it.

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• Balancing internal services using a Cisco CSS 11501

  - by Ladadadada

  First, the background to the problem: I have a Cisco CSS11501 that I am using to load balance a few web servers. These web servers have two network interfaces, one internal and one external and we are sending the requests to the internal interface. We have the CSS configured to do NAT because our webservers need to see the client's IP address. Because the TCP packets hit the webservers with a source address on the Internet, the webserver tries to send the packet back to the client over the external interface and not through the load balancer. In order to stop these requests being sent back out to the Internet via the external interface, we added a routing rule on these boxes so that all traffic with a source address on the internet will use the load balancer as the gateway. This part works fine. What I would also like to to is use the CSS as a load balancer for internal services such as our MySQL slaves. When I do this, I run into a similar problem; the TCP connection goes from the web server to the load balancer and then from the load balancer to the MySQL slave but the CSS spoofs a source address of the original webserver. The MySQL slave then tries to send the response directly to the webserver via the internal network and not via the load balancer. The ideal solution would be to tell the CSS not to do source address spoofing on the internal network and only do it for requests originating on the Internet. Is this possible ? Failing that, is there a way of directing the load balanced traffic back through the load balancer while keeping the other traffic (say SSH) purely on the internal network ? Is there another way of using the CSS11501 to load balance internal services ?

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• xt_TCPMSS: bad length messages

  - by Matic

  Hey! I'm getting loads of messages like: Jun 23 10:24:20 awakening kernel: [ 1691.596823] xt_TCPMSS: bad length (1492 bytes) Jun 23 10:24:21 awakening kernel: [ 1692.663362] xt_TCPMSS: bad length (1448 bytes) Jun 23 10:24:21 awakening kernel: [ 1692.663495] xt_TCPMSS: bad length (1448 bytes) Jun 23 10:24:21 awakening kernel: [ 1692.663588] xt_TCPMSS: bad length (1448 bytes) Jun 23 10:24:21 awakening kernel: [ 1692.663671] xt_TCPMSS: bad length (1440 bytes) Jun 23 10:24:26 awakening kernel: [ 1697.062914] xt_TCPMSS: bad length (474 bytes) Jun 23 10:24:26 awakening kernel: [ 1697.305525] xt_TCPMSS: bad length (1492 bytes) Jun 23 10:24:27 awakening kernel: [ 1698.946633] xt_TCPMSS: bad length (1492 bytes) Jun 23 10:24:36 awakening kernel: [ 1707.481198] xt_TCPMSS: bad length (1492 bytes) Jun 23 10:24:37 awakening kernel: [ 1708.723526] xt_TCPMSS: bad length (805 bytes) Jun 23 10:24:38 awakening kernel: [ 1709.599461] xt_TCPMSS: bad length (805 bytes) Jun 23 10:24:41 awakening kernel: [ 1712.211052] xt_TCPMSS: bad length (1492 bytes) Jun 23 10:24:41 awakening kernel: [ 1712.260588] xt_TCPMSS: bad length (1492 bytes) Jun 23 10:24:41 awakening kernel: [ 1712.976058] xt_TCPMSS: bad length (1492 bytes) Jun 23 10:24:43 awakening kernel: [ 1714.225209] xt_TCPMSS: bad length (1492 bytes) Jun 23 10:24:43 awakening kernel: [ 1714.914961] xt_TCPMSS: bad length (1492 bytes) Jun 23 10:24:55 awakening kernel: [ 1726.192696] xt_TCPMSS: bad length (1480 bytes) Jun 23 10:24:55 awakening kernel: [ 1726.192825] xt_TCPMSS: bad length (1480 bytes) In my dmesg/syslog. This linux machine is among other things used as an internet gateway. Connection is over PPPoE. I have the following line in my iptables script: $IPT -A FORWARD -p tcp --tcp-flags SYN,RST SYN -j TCPMSS --clamp-mss-to-pmtu # PPPoE fix The frequency of this messages increased 10x when I upgraded from Debian lenny with 2.6.27 to squeeze with 2.6.32 few days ago. Why am I seeing this messages and how can I fix them?

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• Load balancing a Windows File Share using HA-Proxy

  - by NathanE

  After pulling my hair out over DFS I just had this weird and potentially dangerous idea come into my head whereby, just possibly, I might be able to use HA-Proxy to load balance a file share between servers. I've done some remedial packet traces and it does appear that TCP port 445 is the only thing involved in using Windows file sharing. I've always thought for many years that UDP 139, 135 etc were also involved in at least establishing the connection - but apparently not! So I setup a basic test: listen SMBTest *:445 mode tcp server Smb1 172.16.61.201:445 server Smb2 172.16.61.202:445 And you'll never guess what... it works??? (!) Now obviously there is the whole concern about synchronisation between the file servers (of course). That could easily be taken care of with a little bit of Robocopy script. And considering I only need a HA read-only file share there wouldn't be any issues with regard to file locking etc. Can anyone tell me if what I'm playing with here is fire? I really didn't think it would work at all and now I'm a little shocked. What would be the downsides? Could this be relied upon for a production environment?

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• Is there a Windows 7 compatible IPSec VPN client that allows protocol and port specific rules?

  - by Sani Huttunen

  As the title says, I need to find a IPSec VPN client for Windows 7. On XP and Vista we've used SafeNet SoftRemote in which you can set up rules for specific protocols and ports. But SoftRemote isn't compatible with Windows 7. 172.xxx.xxx.1 TCP 1433 172.xxx.xxx.2 TCP 1433 172.xxx.xxx.10 ALL ... Since the VPN gateway is configured this way the client must mirror these settings. I've tried TheGreenBow, NCP Secure Entry, Cisco VPN Client and Shrew Soft VPN but none of these allows you to configure by protocol and port. Does anyone have any other suggestions? EDIT: Forgot to mention that agressive mode is also a requirement. --UPDATE-- I've got some news... I've managed to get SoftRemote to work on Windows 7 x64 through Windows XP Mode. After scouring all corners of the Internet for idéas I had enough information to construct a working solution. This solution will probably benefit other clients as well! You'll find a post here with detailed instructions of how I went about.

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• ISA 2000 and COD MW2 Steam

  - by twlichty

  OK, so maybe not the "proper use" of network resources, but we enjoy the odd COD game during lunch hours. When we played COD4, we had a dedicated server setup at the back of the server room. With MW2, we need to be able to connect to steam to be able to play multi-player. I've found this support article here: https://support.steampowered.com/kb%5Farticle.php?ref=8571-GLVN-8711 Which outlines all the ports I need to open. I went through and created the following rules in ISA 2000 (I'm stuck with 2000 for now). Protocol Definition: Steam Primary connection: Port 27000, UDP, Send Receive Secondary Connection: Port range 27001-27030 Send Receive Protocol Definition: Steam TCP In Primary connection: 27014, TCP, Inbound Secondary Connection: Port range: 27015-27050, Inbound Protocol Definition: Steam 4380 Primary connection: 4380, UDP, Send Receive When I start steam on my local workstation (I did add an exception to the Vista Firewall to allow steam), the steam client sits on "Updating Steam" for 5 minutes then errors out with: You must connect to the internet first. Any ideas? I assume I missed something. Thanks for your help.

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• Translating IPTables rule to UFW

  - by Dario Fumagalli

  we are using an Ubuntu 12.04 x64 LTS VPS. Firewall being used is UFW. I have setup a Varnish + LEMP setup. along with other things, including an Openswan IPSEC VPN from our office to the VPS data center. A second in house Ubuntu box is to act as MySQL slave and fetch data from the VPS through the VPN. Master's ppp0 is seen as 10.1.2.1 from the slave, they ping etc. I have done the various required tasks but I can't get the client (slave) MySQL (nor telnet 10.1.2.1 3306) to access the master through the VPN unless I issue this fairly obvious IPTables command: iptables -A INPUT -s 10.1.2.0/24 -p tcp --dport 3306 -j ACCEPT I willingly forced the accepted input to come from the last octet. With this rule everything works just fine! However I want to translate this command to UFW syntax so to keep everything in one place. Now I admit being inexperienced with UFW, I prepared rules like: ufw allow proto tcp from 10.1.2.0/24 port mysql and 2-3 variations involving specifying 3306 instead of mysql, specifying a target IP (MySQL's my.cnf at the moment is configured as 0.0.0.0) and similar but I just don't seem to be able to replicate the simple iptables rule in a functional way. Anyone could kindly give me a suggestion that is not to dump UFW? Thanks in advance.

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• Server 2012, Jumbo Frames - should I expect problems?

  - by TomTom

  Ok, this sound might stupid - but is there any negative on just enabling jumbo frames in practice? From what I understand: Any switch or ethernet adapter that sees a jumbo frame it can not handle will just drop it. TCP is not a problem as max frame size is negotiated in the setinuo phase. UCP is a theoretical problem as a server may just send a LARGE UDP packet that gets dropped on the way. Practically though, as UDP is packet based, I do not really think any software WOULD send a UDP packet larger than 1500 bytes net without app level configuration changes - at least this is how I do my programming, as it is quite hard to get a decent MTU size for that without testing yourself, so you fall back in programming to max 1500 packets. The network in question is a standard small business network - we upgraded now from a non managed 24 port switch to a 52 port switch with 4 10g ports (netgear - quite cheap) and will mov a file server to 10g for also ISCSI serving. All my equipment on the Ethernet level can handle minimum 9000 bytes and due to local firewalls I really want to get packets larger (less firewall processing), but the network is also NAT'ed to the internet. On top, different machines move around (download) large files (multi gigabyte area) quite often for processing. The question is - can I expect problems when I just enable jumbo frames? Again, this is not totally ignorance - I just don't see programs sending more than 1500 byte UDP packets (if that is a practical problem please tell me) and for TCP the MTU is negotiated anyway. if there is a problem I can move to a dedicated VLAN, but this has it's own shares of problems as basically most workstations must then be on both VLAN's.

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