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  • Error in connection in ruby.

    - by piemesons
    require 'rubygems' require 'mysql' db = Mysql.connect('localhost', 'root', '', 'mohit') //db.rb:4: undefined method `connect' for Mysql:Class (NoMethodError) //undefined method `real_connect' for Mysql:Class (NoMethodError) db.query("CREATE TABLE people ( id integer primary key, name varchar(50), age integer)") db.query("INSERT INTO people (name, age) VALUES('Chris', 25)") begin query = db.query('SELECT * FROM people') puts "There were #{query.num_rows} rows returned" query.each_hash do |h| puts h.inspect end rescue puts db.errno puts db.error end error i am geting is: undefined method `connect' for Mysql:Class (NoMethodError) OR undefined method `real_connect' for Mysql:Class (NoMethodError) EDIT return value of Mysql.methods ["private_class_method", "inspect", "name", "tap", "clone", "public_methods", "object_id", "__send__", "method_defined?", "instance_variable_defined?", "equal?", "freeze", "extend", "send", "const_defined?", "methods", "ancestors", "module_eval", "instance_method", "hash", "autoload?", "dup", "to_enum", "instance_methods", "public_method_defined?", "instance_variables", "class_variable_defined?", "eql?", "constants", "id", "instance_eval", "singleton_methods", "module_exec", "const_missing", "taint", "instance_variable_get", "frozen?", "enum_for", "private_method_defined?", "public_instance_methods", "display", "instance_of?", "superclass", "method", "to_a", "included_modules", "const_get", "instance_exec", "type", "<", "protected_methods", "<=>", "class_eval", "==", "class_variables", ">", "===", "instance_variable_set", "protected_instance_methods", "protected_method_defined?", "respond_to?", "kind_of?", ">=", "public_class_method", "to_s", "<=", "const_set", "allocate", "class", "new", "private_methods", "=~", "tainted?", "__id__", "class_exec", "autoload", "untaint", "nil?", "private_instance_methods", "include?", "is_a?"] return value of Mysql.methods(false) is []... blank array

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  • .Net SQL Server Connection String - hide password from other developers

    - by Chris Klepeis
    We're migrating one of our sites to ASP.Net. We do not want to use integrated security, which uses the windows account to connect to sql server (not going to get into why, its just out of the question). We created a username and password to connect to SQL Server, and would like to use that username and password, however, we also do not want other developers to see this information (easily read from the web.config).... I know it can be encrypted, but it can just as easily be decrypted by the developers - plus encryption has a performance hit. Is there any solution to this problem?

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  • openvpn TCP/UDP slow SSH/SMB performance

    - by Petr Latal
    I have question about strange behavior of my openVPN configuration on Debian lenny. I have 2 server configs (one proto tcp-server based and one proto udp based). ISP bandwidth is 7Mbit/7Mbit. When I uses proto tcp-server my download server rate is fine around 6,4 Mbit/s, but upload rate is about 3Mbit/s. When I uses proto udp, my download server rate is around 3Mbit/s and upload rate around 6,4Mbit/s. I tried to handle the MTU, MSSFIX and cipher on/off on server and client configs to synchronize rates, but without solution. Here is TCP based SERVER config: mode server tls-server port 1194 proto tcp-server dev tap0 ifconfig 11.10.15.1 255.255.255.0 ifconfig-pool 11.10.15.2 11.10.15.20 255.255.255.0 push "route 192.168.1.0 255.255.255.0" push "dhcp-option DNS 192.168.1.200" push "route-gateway 11.10.15.1" push "dhcp-option WINS 192.168.1.200" route-up /etc/openvpn/routeup.sh duplicate-cn ca /etc/openvpn/ca.crt cert /etc/openvpn/server.crt key /etc/openvpn/server.key dh /etc/openvpn/dh2048.pem log-append /var/log/openvpn.log status /var/run/vpn.status 10 user nobody group nogroup keepalive 10 120 comp-lzo verb 3 script-security 3 plugin /usr/lib/openvpn/openvpn-auth-pam.so system-auth persist-tun persist-key mssfix cipher BF-CBC Here is UDP based SERVER config: port 1194 proto udp dev tun0 local xx.xx.xx.xx server 11.10.15.0 255.255.255.0 ca /etc/openvpn/ca.crt cert /etc/openvpn/server.crt key /etc/openvpn/server.key dh /etc/openvpn/dh2048.pem log-append /var/log/openvpn.log status /var/run/vpn.status 10 user nobody group nogroup keepalive 10 120 comp-lzo verb 3 duplicate-cn script-security 3 plugin /usr/lib/openvpn/openvpn-auth-pam.so system-auth persist-tun persist-key tun-mtu 1500 mssfix 1212 client-to-client ifconfig-pool-persist ipp.txt Here is TCP/UDP based windows CLIENT config: remote xx.xx.xx.xx --socket-flags TCP_NODELAY tls-client port 1194 proto tcp-client #proto udp dev tap #dev tun pull ca ca.crt cert latis.crt key latis.key mute 0 comp-lzo adaptive verb 3 resolv-retry infinite nobind persist-key auth-user-pass auth-nocache script-security 2 mssfix cipher BF-CBC

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  • nmap on my webserver shows TCP ports 554 and 7070 open

    - by atc
    I have a webserver that hosts various websites for me. The two services that are accessible outside are SSH and Apache2. These are running on a non-standard and standard port, respectively. All other ports are closed explicitly via arno-iptables-firewall. The host is running Debian Testing. I noticed that a scan of the host using nmap produced different results from different PCs. From my laptop on my home network (behind a BT Homehub), I get the following: Not shown: 996 filtered ports PORT STATE SERVICE 80/tcp open http 554/tcp open rtsp 7070/tcp open realserver 9000/tcp open cslistener whereas scanning from a US-based server with nmap 5.00 and a Linux box in Norway running nmap 5.21 I get the following: Not shown: 998 filtered ports PORT STATE SERVICE 80/tcp open http 9000/tcp open cslistener so I hope it's my internal network or ISP that's playing up, but I cannot be sure. Running a netstat -l | grep 7070 produces nothing. Similarly for port 554. Can anyone explain the peculiarities I'm seeing?

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  • Huawei 3G modem disconnects after successful connection

    - by theo
    I'm having a severe connection problem in Ubuntu 12.04 that renders the OS almost useless. I have a Huawei E352 3G modem. Ubuntu detects it as a mobile broadband connection without any problem. I created a new connection by providing APN. Now after connection it disconnects after a few seconds, and the modem disappears from mobile broadband list. I tried various workarounds but neither worked. I had no problem in Ubuntu 11.10.

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  • Else statement to show connection successful [closed]

    - by Craig Smith
    I am trying to write a script to test a database connection, at the moment it will only display text if the connection doesn't work, I am stuck with trying to create an else statement to display "Connection Successful" if it works. Here's my code so far. Any help appreciated :) <? $conn = @mysql_connect("localhost", "root", ""); if (!$conn) { die("Connection failed: " .mysql_error()); } ?>

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  • No wired and wireless connection found after upgrading 12.04

    - by ag108
    After upgrading 12.04 LTS, my wired connection works but no wireless connection found. I tried many suggestion for wireless connection on Ubuntu forum but nothing works for me. Now, maybe by mistake, I am also unable to connect Internet through wired connection. Now, (1) its says "No network devices available" and (2) in System Settings ? Hardware ? no additional driver icon is showing Please help. I don't know much about Ubuntu.

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  • Where is the network connection enabled/disabled setting stored?

    - by minerj
    I have an Amazon EC2 instance of Windows Server 2008 where some genius managed to disable the network connection so that the instance is now isolated in its own little universe. I can shut down the instance and edit the "C:\" drive volume by attaching it to another running instance. This is equivalent to removing the system drive from a dead machine and attaching it to another computer to edit the files. Question: Where is the network connection enabled / disabled setting stored? If I can tweak this setting by editing the registry or a file to re-enable the network connection, I can then resurrect my Amazon server.

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  • Is a live internet connection required for push notification?

    - by Heshan Perera
    This maybe a silly question, but I need confirmation and I have no one else to ask. I am trying to understand the implications of implementing my own push notification for android mobile devices. This requires a continuous TCP connection to a server, though most of the time it will be idle. My assumption is that, even when idle, for the server to be able to push data to the client through the TCP connection, an active internet connection will always be required, and if the connection is disrupted (i.e. the user switches the connection off) this push will no longer be possible. Is this assumption correct ?

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  • How can I diagnose "Cannot determine peer address" in my Perl TCP script?

    - by MadBoy
    I've this little script which does it's job pretty well but sometimes it tends to fail. It fails in 2 cases: with error send: Cannot determine peer address at ./tcp-new.pl line 52 with no output or anything, it just fails to deliver what it got to connected Tcp Client. Usually it happens after I disconnect from server, go home and connect it again. To fix this restart is required and it starts working. Sometimes this problem is followed by problem mentioned in point 1. Note: it's not problem when I disconnect and reconnect to it again within short amount of time (unless error nr 1 happens). So can anyone help me make this code be a bit more stable so I don't have to restart it every day? #!/usr/bin/perl use strict; use warnings; use IO::Socket; use IO::Select; my $tcp_port = "10008"; my $udp_port = "2099"; my $tcp_socket = IO::Socket::INET->new( Listen => SOMAXCONN, LocalPort => $tcp_port, Proto => 'tcp', ReuseAddr => 1, ); my $udp_socket = IO::Socket::INET->new( LocalPort => $udp_port, Proto => 'udp', ); my $read_select = IO::Select->new(); my $write_select = IO::Select->new(); $read_select->add($tcp_socket); $read_select->add($udp_socket); while (1) { my @read = $read_select->can_read(); foreach my $read (@read) { if ($read == $tcp_socket) { my $new_tcp = $read->accept(); $write_select->add($new_tcp); } elsif ($read == $udp_socket) { my $recv_buffer; $udp_socket->recv($recv_buffer, 1024, undef); my @write = $write_select->can_write(); foreach my $write (@write) { $write->send($recv_buffer); } } } }

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  • Update Manager got stuck (but not frozen) while installing downloaded updates. What should I do?

    - by WarriorIng64
    I have just gotten my Ubuntu 12.04 LTS desktop computer reassembled after a trip back home and connected it to my parent's wireless Internet connection. The connection seems quite shaky (disconnects half the time, likely an ongoing issue with the wireless card I have installed), and it struggled to download updates because of the constant interruptions. Eventually, it managed to download the updated packages and started installing them. I got up and left it to do its work. When I came back, I saw it was still having trouble staying connected to the wireless (no surprise there), but then I noticed that it seemed like Update Manager had stopped making progress on the installation. I opened the Details pane to see what it was last doing: My guess was that the installation script for flashplugin-installer couldn't complete the download until I stabilized the Internet connection. I hooked my Ubuntu laptop up to my desktop via Ethernet and shared its wireless connection using this guide, and as I am typing this now from my desktop you can see that the connection issue was successfully worked around. However, even with a stable connection established, Update Manager seems "stuck" at its current position and won't go any further. It's not totally frozen, but I can't do anything beyond open/close the Details pane as the Cancel button is grayed out. I know it can cause big problems if updates are stopped during installation, but I'm at a loss as to how this situation should be handled. I'm sure it should finish normally if I can just find a way to restart Update Manager, but the question is how this should be approached. How can I safely get my updates to finish installing?

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  • Exploring TCP throughput with DTrace (2)

    - by user12820842
    Last time, I described how we can use the overlap in distributions of unacknowledged byte counts and send window to determine whether the peer's receive window may be too small, limiting throughput. Let's combine that comparison with a comparison of congestion window and slow start threshold, all on a per-port/per-client basis. This will help us Identify whether the congestion window or the receive window are limiting factors on throughput by comparing the distributions of congestion window and send window values to the distribution of outstanding (unacked) bytes. This will allow us to get a visual sense for how often we are thwarted in our attempts to fill the pipe due to congestion control versus the peer not being able to receive any more data. Identify whether slow start or congestion avoidance predominate by comparing the overlap in the congestion window and slow start distributions. If the slow start threshold distribution overlaps with the congestion window, we know that we have switched between slow start and congestion avoidance, possibly multiple times. Identify whether the peer's receive window is too small by comparing the distribution of outstanding unacked bytes with the send window distribution (i.e. the peer's receive window). I discussed this here. # dtrace -s tcp_window.d dtrace: script 'tcp_window.d' matched 10 probes ^C cwnd 80 10.175.96.92 value ------------- Distribution ------------- count 1024 | 0 2048 | 4 4096 | 6 8192 | 18 16384 | 36 32768 |@ 79 65536 |@ 155 131072 |@ 199 262144 |@@@ 400 524288 |@@@@@@ 798 1048576 |@@@@@@@@@@@@@@@@@@@@@@@@@@@@ 3848 2097152 | 0 ssthresh 80 10.175.96.92 value ------------- Distribution ------------- count 268435456 | 0 536870912 |@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@ 5543 1073741824 | 0 unacked 80 10.175.96.92 value ------------- Distribution ------------- count -1 | 0 0 | 1 1 | 0 2 | 0 4 | 0 8 | 0 16 | 0 32 | 0 64 | 0 128 | 0 256 | 3 512 | 0 1024 | 0 2048 | 4 4096 | 9 8192 | 21 16384 | 36 32768 |@ 78 65536 |@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@ 5391 131072 | 0 swnd 80 10.175.96.92 value ------------- Distribution ------------- count 32768 | 0 65536 |@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@ 5543 131072 | 0 Here we are observing a large file transfer via http on the webserver. Comparing these distributions, we can observe: That slow start congestion control is in operation. The distribution of congestion window values lies below the range of slow start threshold values (which are in the 536870912+ range), so the connection is in slow start mode. Both the unacked byte count and the send window values peak in the 65536-131071 range, but the send window value distribution is narrower. This tells us that the peer TCP's receive window is not closing. The congestion window distribution peaks in the 1048576 - 2097152 range while the receive window distribution is confined to the 65536-131071 range. Since the cwnd distribution ranges as low as 2048-4095, we can see that for some of the time we have been observing the connection, congestion control has been a limiting factor on transfer, but for the majority of the time the receive window of the peer would more likely have been the limiting factor. However, we know the window has never closed as the distribution of swnd values stays within the 65536-131071 range. So all in all we have a connection that has been mildly constrained by congestion control, but for the bulk of the time we have been observing it neither congestion or peer receive window have limited throughput. Here's the script: #!/usr/sbin/dtrace -s tcp:::send / (args[4]-tcp_flags & (TH_SYN|TH_RST|TH_FIN)) == 0 / { @cwnd["cwnd", args[4]-tcp_sport, args[2]-ip_daddr] = quantize(args[3]-tcps_cwnd); @ssthresh["ssthresh", args[4]-tcp_sport, args[2]-ip_daddr] = quantize(args[3]-tcps_cwnd_ssthresh); @unacked["unacked", args[4]-tcp_sport, args[2]-ip_daddr] = quantize(args[3]-tcps_snxt - args[3]-tcps_suna); @swnd["swnd", args[4]-tcp_sport, args[2]-ip_daddr] = quantize((args[4]-tcp_window)*(1 tcps_snd_ws)); } One surprise here is that slow start is still in operation - one would assume that for a large file transfer, acknowledgements would push the congestion window up past the slow start threshold over time. The slow start threshold is in fact still close to it's initial (very high) value, so that would suggest we have not experienced any congestion (the slow start threshold is adjusted when congestion occurs). Also, the above measurements were taken early in the connection lifetime, so the congestion window did not get a changes to get bumped up to the level of the slow start threshold. A good strategy when examining these sorts of measurements for a given service (such as a webserver) would be start by examining the distributions above aggregated by port number only to get an overall feel for service performance, i.e. is congestion control or peer receive window size an issue, or are we unconstrained to fill the pipe? From there, the overlap of distributions will tell us whether to drill down into specific clients. For example if the send window distribution has multiple peaks, we may want to examine if particular clients show issues with their receive window.

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  • iptables is not allowing me to contact my dns nameservers

    - by user1272737
    I have the follwing iptables rules: Chain INPUT (policy DROP) target prot opt source destination ACCEPT tcp -- anywhere anywhere tcp dpt:ssh ACCEPT tcp -- anywhere anywhere tcp dpt:http ACCEPT tcp -- anywhere anywhere tcp dpt:https ACCEPT tcp -- localhost.localdomain anywhere tcp dpt:mysql ACCEPT tcp -- anywhere anywhere tcp dpt:14443 ACCEPT tcp -- anywhere anywhere tcp dpt:ftp ACCEPT tcp -- anywhere anywhere tcp dpt:ftp-data ACCEPT tcp -- anywhere anywhere tcp dpt:xxxxxxx Chain FORWARD (policy ACCEPT) target prot opt source destination Chain OUTPUT (policy ACCEPT) target prot opt source destination When I turn off iptables I am able to use wget and all other commands. When these rules are enabled I cannot connect to any address. Any idea why this would be?

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  • Debian, 6rd tunnel, and connection troubles

    - by Chris B
    Long story short I am having issues with IPv6 using a 6rd tunnel with my ISP, charter business. They offer a 6rd tunnel that I think I have properly set up, but the server doesn’t reply to every ipv6 request. When the server has the network interfaces idle with no traffic for about 10 minutes, then IPv6 stops accepting inbound connections. to re-allow it, I must go into the server, and make it do a outbound ipv6 connection (normally a ping) to start it back up. Whats weird though i that if I run iptraf when its not working, it still shows a inbound ipv6 packet… the server is just not replying, and I can’t figure out why. Also, if I try to access my server over IPv6 from a house about 1 mile away on the same ISP, it is never able to connect. it always times out, but again the iptraf shows a ipv6 inbound packet. Again, it just does not reply. To test if my server is accessible through IPv6 I always have to use my vzw 4g phone (they use IPv6) or ipv6proxy dot net. Here is all of the configuration information my ISP gives on there tunnel server: 6rd Prefix = 2602:100::/32 Border Relay Address = 68.114.165.1 6rd prefix length = 32 IPv4 mask length = 0 Here is my /etc/network/interfaces for ipv6 (used x's to block real addresses) auto charterv6 iface charterv6 inet6 v4tunnel address 2602:100:189f:xxxx::1 netmask 32 ttl 64 gateway ::68.114.165.1 endpoint 68.114.165.1 local 24.159.218.xxx up ip link set mtu 1280 dev charterv6 here is my iptables config filter :INPUT DROP [0:0] :fail2ban-ssh – [0:0] :OUTPUT ACCEPT [0:0] :FORWARD DROP [0:0] :hold – [0:0] -A INPUT -p tcp -m tcp —dport 22 -j fail2ban-ssh -A INPUT -m state —state RELATED,ESTABLISHED -j ACCEPT -A INPUT -p tcp -m multiport -j ACCEPT —dports 80,443,25,465,110,995,143,993,587,465,22 -A INPUT -i lo -j ACCEPT -A INPUT -p tcp -m tcp —dport 10000 -j ACCEPT -A INPUT -p tcp -m tcp —dport 5900:5910 -j ACCEPT -A fail2ban-ssh -j RETURN -A INPUT -p icmp -j ACCEPT COMMIT and last here is my ip6tables firewall config filter :INPUT DROP [1653:339023] :FORWARD DROP [0:0] :OUTPUT ACCEPT [60141:13757903] :hold – [0:0] -A INPUT -m state —state RELATED,ESTABLISHED -j ACCEPT -A INPUT -p tcp -m multiport —dports 80,443,25,465,110,995,143,993,587,465,22 -j ACCEPT -A INPUT -i lo -j ACCEPT -A INPUT -p tcp -m tcp —dport 10000 -j ACCEPT -A INPUT -p tcp -m tcp —dport 5900:5910 -j ACCEPT -A INPUT -p ipv6-icmp -j ACCEPT COMMIT So Summary: 1.iptraf always shows IPv6 traffic, so its always making it to the server 2.server stops replying on ipv6 after no traffic for awhile (10 minutesish) until a outbound connection is made, then the process repeats. 3.server is NEVER accessable vi same ISP (yet iptraf still shows ipv6 request) Notes: When I try to access it from the same ISP from across town, even with iptables and ip6tables allowing ALL inbound traffic, this is what iptraf shows. IPv6 (92 bytes) from 97.92.18.xxx to 24.159.218.xxx on eth0 ICMP dest unrch (port) (120 bytes) from 24.159.218.xxx to 97.92.18.xxx on eth1 its strange, like its trying to forward to LAN? (eth1 is LAN, eth0 is WAN) even with the IPv6 address being set in the hosts file to the servers domain name. With iptables set up normally with the above configurations it only says this: IPv6 (100 bytes) from 97.92.18.xxx to 24.159.218.xxx on eth0 Im REALLY stuck on this, and any help would be GREATLY appreciated.

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  • WCF- "The underlying connection was closed: The connection was closed unexpectedly"

    - by SumGuy
    Hi there. I'm recieving that wonderfuly ambiguous error message when using one of my webmethods on my WCF webservice. As that error message doesn't provide any explanation whatsoever allow me to post my theory. I believe it may have something to do with the return type I'm using I have a Types DLL which is refrenced in both the webservice and the client. In this DLL is the base class ExceptionMessages. There is a child of this class called DrawingExcepions. Here is some code: public class ExceptionMessages { public object[] ReturnValue { get; set; } } public class DrawingExceptions : ExceptionMessages { private List<DrawingException> des = new List<DrawingException>(); } public class DrawingException { public Exception ExceptionMsg { get; set; } public List<object> Errors { get; set; } } The using code: [OperationContract] ExceptionMessages createNewBom(Bom bom, DrawingFiles dfs); public ExceptionMessages createNewBOM(Bom bom, DrawingFiles dfs) { return insertAssembly(bom, dfs); } public DrawingExceptions insertAssembly(Bom bom, DrawingFiles dfs) { DrawingExceptions des = new DrawingExceptions(); foreach (DrawingFile d in dfs.drawingFiles) { DrawingException temp = insertNewDrawing(bom, d); if (temp != null) des.addDrawingException(temp); if (d.Child != null) des.addDrawingException(insertAssembly(bom, d.Child)); } return des; } Returns to: ExceptionMessages ems = client.createNewBom(bom, currentDFS); if (ems is DrawingExceptions) { } Basically the return type from the webmethod is ExceptionMessages however I would usually be sending the child class back instead. My only idea is that it's the child that's causing the error but as far as I've read, this should have no effect. Has anyone got any ideas what could be going wrong here? If any more info is required, just ask :) Thanks.

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  • TCP: Address already in use exception - possible causes for client port? NO PORT EXHAUSTION

    - by TomTom
    Hello, stupid problem. I get those from a client connecting to a server. Sadly, the setup is complicated making debugging complex - and we run out of options. The environment: *Client/Server system, both running on the same machine. The client is actually a service doing some database manipulation at specific times. * The cnonection comes from C# going through OleDb to an EasySoft JDBC driver to a custom written JDBC server that then hosts logic in C++. Yeah, compelx - but the third party supplier decided to expose the extension mechanisms for their server through a JDBC interface. Not a lot can be done here ;) The Symptom: At (ir)regular intervals we get a "Address already in use: connect" told from the JDBC driver. They seem to come from one particular service we run. Now, I did read all the stuff about port exhaustion. This is why we have a little tool running now that counts ports and their states every minute. Last time this happened, we had an astonishing 370 ports in use, with the count rising to about 900 AFTER the error. We aleady patched the registry (it is a windows machine) to allow more than the 5000 client ports standard, but even then, we are far far from that limit to start with. Which is why I am asking here. Ayneone an ide what ELSE could cause this? It is a Windows 2003 Server machine, 64 bit. The only other thing I can see that may cause it (but this functionality is supposedly disabled) is Symantec Endpoint Protection that is installed on the server - and being capable of actinc as a firewall, it could possibly intercept network traffic. I dont want to open a can of worms by pointing to Symantec prematurely (if pointing to Symantec can ever be seen as such). So, anyone an idea what else may be the cause? Thanks

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  • Do TCP connections work differently within the same subnet?

    - by Dean
    I've encountered some network behaviour that confuses me while trying to get Java RMI working. I use netcat to connect to a local machine: [my_machine]$ nc -w 1 192.168.0.100 60000 && echo success success I try to do the same to my server: [my_machine]$ nc -w 1 my-servers-ip 60000 && echo success This doesn't work, unless I explicitly listen on the server socket: [amazon_ec2]$ nc -l 60000 [my_machine]$ nc -w 1 my-servers-ip 60000 && echo success success For the version that fails, the SYN packet receives a RST, ACK in response. I'm not too knowledgable about this stuff, at this point I only have wild theories such as the one in the question. Any ideas? Potentially useful details: Local Machine (192.168.0.100) - Macbook Remote Machine (Amazon EC2) - Amazon Linux AMI 2012.03 Security Group Settings: 22 (SSH) 0.0.0.0/0 1099 0.0.0.0/0 49152-65535 0.0.0.0/0 "iptables -L" shows no rules set

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  • TCP/IP RST being sent differently in different browsers.

    - by Brian
    On Mac OS X (10.6), if I start a YouTube video download and pull the Ethernet cable for 5 or so seconds, then plug it back in, I get varying results depending on the browser. With Opera and Chrome, after I plug the cable back in the video continues to load. But with Safari and Firefox, it never does. Using Wireshark to look at the traffic, I found that Opera and Chrome simply ACK the first packet from YouTube after the cable has been plugged back in, but Safari and Firefox set the RST flag (0x4) in the TCP header and no more traffic follows. I can put a HUB in between the machine and the internet connection, the problem goes away and all four browsers continue loading the video when the cable is plugged back into the HUB. Again, looking at the Wireshark logs, it's evident that the machine doesn't see the Mulitcast connection close and there is simply a delay in the packets flowing through. So it seems that if Safari and Firefox sees a Multicast connection close, and then later see data on that same connection, they will send a RST. My question is why? What is the correct course of action, and why are 2/4 browsers doing it one way, while the other 2/4 are doing it another way? Is there somewhere in the code that I can see where this is happening in Firefox, for instance? Thank you very much.

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  • Why do I see different TCP behaviour between IIS and FTP server applications on Windows 2003?

    - by rupello
    I am comparing Wireshark traces of a 10MB file download file from: the FileZilla FTP server and IIS (using HTTP) on the same Windows 2003 server. The FTP download performs faster and the trace shows the server behaving as expected, sending more data to the client with every ACK received: Link to full-size image The HTTP server trace shows a more bursty pattern. The timing of the send bursts are sometimes unrelated to any ACKs received from the client (circled in red): Link to full-size image Anyone have a suggestion as to why IIS traffic is having like this? Update: We have tried modifying the http.sys registry settings (setting MaxBytesPerSend to 256k and MaxBufferedSendBytes to 64k as recommended). Changing MaxBytesPerSend does seem to improve performance by increasing the amount of in-flight data , but we still see the same bursty pattern.

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  • Server Firewall preventing sending of email [migrated]

    - by Jo Fitzgerald
    The firewall on my VPS appears to be preventing my site from sending email. It was working fine until the end of last month. My hosting provider (Webfusion) has been next to useless. I am able to send email if I open INPUT ports 32768-65535, but not if these ports are closed. Why would this be? I have the following rules in my firewall: # sudo iptables -L Chain INPUT (policy DROP) target prot opt source destination VZ_INPUT all -- anywhere anywhere Chain FORWARD (policy DROP) target prot opt source destination VZ_FORWARD all -- anywhere anywhere Chain OUTPUT (policy DROP) target prot opt source destination VZ_OUTPUT all -- anywhere anywhere Chain VZ_FORWARD (1 references) target prot opt source destination Chain VZ_INPUT (1 references) target prot opt source destination ACCEPT tcp -- anywhere anywhere tcp dpt:www ACCEPT tcp -- anywhere anywhere tcp dpt:https ACCEPT tcp -- anywhere anywhere tcp dpt:smtp ACCEPT tcp -- anywhere anywhere tcp dpt:ssmtp ACCEPT tcp -- anywhere anywhere tcp dpt:pop3 ACCEPT tcp -- anywhere anywhere tcp dpt:domain ACCEPT udp -- anywhere anywhere udp dpt:domain ACCEPT tcp -- anywhere anywhere tcp dpts:32768:65535 ACCEPT udp -- anywhere anywhere udp dpts:32768:65535 ACCEPT tcp -- localhost.localdomain localhost.localdomain ACCEPT udp -- localhost.localdomain localhost.localdomain Chain VZ_OUTPUT (1 references) target prot opt source destination ACCEPT tcp -- anywhere anywhere ACCEPT udp -- anywhere anywhere The VPS is running Plesk 10.4.4 (please ask if you require further technical information to help me)

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  • Connection Pooling is Busted

    - by MightyZot
    A few weeks ago we started getting complaints about performance in an application that has performed very well for many years.  The application is a n-tier application that uses ADODB with the SQLOLEDB provider to talk to a SQL Server database.  Our object model is written in such a way that each public method validates security before performing requested actions, so there is a significant number of queries executed to get information about file cabinets, retrieve images, create workflows, etc.  (PaperWise is a document management and workflow system.)  A common factor for these customers is that they have remote offices connected via MPLS networks. Naturally, the first thing we looked at was the query performance in SQL Profiler.  All of the queries were executing within expected timeframes, most of them were so fast that the duration in SQL Profiler was zero.  After getting nowhere with SQL Profiler, the situation was escalated to me.  I decided to take a peek with Process Monitor.  Procmon revealed some “gaps” in the TCP/IP traffic.  There were notable delays between send and receive pairs.  The send and receive pairs themselves were quite snappy, but quite often there was a notable delay between a receive and the next send.  You might expect some delay because, presumably, the application is doing some thinking in-between the pairs.  But, comparing the procmon data at the remote locations with the procmon data for workstations on the local network showed that the remote workstations were significantly delayed.  Procmon also showed a high number of disconnects. Wireshark traces showed that connections to the database were taking between 75ms and 150ms.  Not only that, but connections to a file share containing images were taking 2 seconds!  So, I asked about a trust.  Sure enough there was a trust between two domains and the file share was on the second domain.  Joining a remote workstation to the domain hosting the share containing images alleviated the time delay in accessing the file share.  Removing the trust had no affect on the connections to the database. Microsoft Network Monitor includes filters that parse TDS packets.  TDS is the protocol that SQL Server uses to communicate.  There is a certificate exchange and some SSL that occurs during authentication.  All of this was evident in the network traffic.  After staring at the network traffic for a while, and examining packets, I decided to call it a night.  On the way home that night, something about the traffic kept nagging at me.  Then it dawned on me…at the beginning of the dance of packets between the client and the server all was well.  Connection pooling was working and I could see multiple queries getting executed on the same connection and ethereal port.  After a particular query, connecting to two different servers, I noticed that ADODB and SQLOLEDB started making repeated connections to the database on different ethereal ports.  SQL Server would execute a single query and respond on a port, then open a new port and execute the next query.  Connection pooling appeared to be broken. The next morning I wrote a test to confirm my hypothesis.  Turns out that the sequence causing the connection nastiness goes something like this: Make a connection to the database. Open a result set that returns enough records to require multiple roundtrips to the server. For each result, query for some other data in the database (this will open a new implicit connection.) Close the inner result set and repeat for every item in the original result set. Close the original connection. Provided that the first result set returns enough data to require multiple roundtrips to the server, ADODB and SQLOLEDB will start making new connections to the database for each query executed in the loop.  Originally, I thought this might be due to Microsoft’s denial of service (ddos) attack protection.  After turning those features off to no avail, I eventually thought to switch my queries to client-side cursors instead of server-side cursors.  Server-side cursors are the default, by the way.  Voila!  After switching to client-side cursors, the disconnects were gone and the above sequence yielded two connections as expected. While the real problem is the amount of time it takes to make connections over these MPLS networks (100ms on average), switching to client-side cursors made the problem go away.  Believe it or not, this is actually documented by Microsoft, and rather difficult to find.  (At least it was while we were trying to troubleshoot the problem!)  So, if you’re noticing performance issues on slower networks, or networks with slower switching, take a look at the traffic in a tool like Microsoft Network Monitor.  If you notice a high number of disconnects, and you’re using fire-hose or server-side cursors, then try switching to client-side cursors and you may see the problem go away. Most likely, Microsoft believes this to be appropriate behavior, because ADODB can’t guarantee that all of the data has been retrieved when you execute the inner queries.  I’m not convinced, though, because the problem remains even after replacing all of the implicit connections with explicit connections and closing those connections in-between each of the inner queries.  In that case, there doesn’t seem to be a reason why ADODB can’t use a single connection from the connection pool to make the additional queries, bringing the total number of connections to two.  Instead ADO appears to make an assumption about the state of the connection. I’ve reported the behavior to Microsoft and am awaiting to hear from the appropriate team, so that I can demonstrate the problem.  Maybe they can explain to us why this is appropriate behavior.  :)

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  • Check connection and reconnect wifi

    - by Ruud
    I'm building a wireless photoframe. The one thing I haven't been able to figure out is how to get my wifi connection back up using a recommended method. Right now I edited /etc/network/interfaces so wlan0 is started at boot: auto wlan0 iface wlan0 inet dhcp wireless-essid ourssid This method works fine for booting. But I found that if I do not check the connection for a long time (could be a week) it might be down. So I should reconnect. What I do now to verify the connection is working is downloading a file from the server that can't be cached (http://server.ext/ping.php?randomize=123456) If I fail to retrieve the file I assume that the connection is no longer working and I run a shell script like #!/bin/bash ifconfig wlan0 up iwconfig wlan0 essid "ourssid" dhclient wlan0 And the connection comes back. But I can't find anything if this is in any way a good method. Can this be improved upon, or is this already right?

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  • Software centre and Evolution think I am offline using WICD to make wireless connection

    - by Alex
    I upgraded to 11.10 yesterday. I use WICD to make the wireless connection because I have never managed to get network manager to make a wireless connection on any computer I have installed it on. But since 11.10 both Evolution and software centre are convinced I am offline even though I have a functional connection (I am using wifi now and both are reporting me offline, which I clearly am not). I am using an MSI WIND clone Advent 4211 B netbook. Network manager has never worked on this computer for wifi. WICD can make connection about 30% time (often returns BAD PASSWORD, first few attempts). XP of course works fine to make wifi connection. I have a I am happy to supply more information I just do not know what information might help. I have reported a bug against evolution

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