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• apache chokes after 300 connections

  - by john titus

  We have an apache webserver in front of Tomcat hosted on EC2, instance type is extra large with 34GB memory. Our application deals with lot of external webservices and we have a very lousy external webservice which takes almost 300 seconds to respond to requests during peak hours. During peak hours the server chokes at just about 300 httpd processes. ps -ef | grep httpd | wc -l =300 I have googled and found numerous suggestions but nothing seems to work.. following are some configuration i have done which are directly taken from online resources. I have increased the limits of max connection and max clients in both apache and tomcat. here are the configuration details: //apache <IfModule prefork.c> StartServers 100 MinSpareServers 10 MaxSpareServers 10 ServerLimit 50000 MaxClients 50000 MaxRequestsPerChild 2000 </IfModule> //tomcat <Connector port="8080" protocol="org.apache.coyote.http11.Http11NioProtocol" connectionTimeout="600000" redirectPort="8443" enableLookups="false" maxThreads="1500" compressableMimeType="text/html,text/xml,text/plain,text/css,application/x-javascript,text/vnd.wap.wml,text/vnd.wap.wmlscript,application/xhtml+xml,application/xml-dtd,application/xslt+xml" compression="on"/> //Sysctl.conf net.ipv4.tcp_tw_reuse=1 net.ipv4.tcp_tw_recycle=1 fs.file-max = 5049800 vm.min_free_kbytes = 204800 vm.page-cluster = 20 vm.swappiness = 90 net.ipv4.tcp_rfc1337=1 net.ipv4.tcp_max_orphans = 65536 net.ipv4.ip_local_port_range = 5000 65000 net.core.somaxconn = 1024 I have been trying numerous suggestions but in vain.. how to fix this? I'm sure m2xlarge server should serve more requests than 300, probably i might be going wrong with my configuration.. The server chokes only during peak hours and when there are 300 concurrent requests waiting for the [300 second delayed] webservice to respond. Please help..

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• Can not open port 3306 on Ubuntu using iptables

  - by user94626

  I am trying to open port 3306 (for remote mysql connections) on my ubuntu 12.04 server machine but for the life of me can't get the damned thing to work! Here is what I did: 1) list current firewall rules: $> sudo iptables -nL -v output: Chain INPUT (policy ACCEPT 0 packets, 0 bytes) pkts bytes target prot opt in out source destination 225 16984 fail2ban-ssh tcp -- * * 0.0.0.0/0 0.0.0.0/0 multiport dports 22 220 69605 ACCEPT all -- lo * 0.0.0.0/0 0.0.0.0/0 0 0 REJECT all -- lo * 0.0.0.0/0 127.0.0.0/8 reject-with icmp-port-unreachable 486 54824 ACCEPT all -- * * 0.0.0.0/0 0.0.0.0/0 state RELATED,ESTABLISHED 1 60 ACCEPT tcp -- * * 0.0.0.0/0 0.0.0.0/0 tcp dpt:80 19 988 ACCEPT tcp -- * * 0.0.0.0/0 0.0.0.0/0 tcp dpt:443 1 52 ACCEPT tcp -- * * 0.0.0.0/0 0.0.0.0/0 state NEW tcp dpt:22 0 0 ACCEPT icmp -- * * 0.0.0.0/0 0.0.0.0/0 icmptype 8 4 208 LOG all -- * * 0.0.0.0/0 0.0.0.0/0 limit: avg 5/min burst 5 LOG flags 0 level 7 prefix "iptables denied: " 4 208 REJECT all -- * * 0.0.0.0/0 0.0.0.0/0 reject-with icmp-port-unreachable Chain FORWARD (policy ACCEPT 0 packets, 0 bytes) pkts bytes target prot opt in out source destination 0 0 REJECT all -- * * 0.0.0.0/0 0.0.0.0/0 reject-with icmp-port-unreachable Chain OUTPUT (policy ACCEPT 0 packets, 0 bytes) pkts bytes target prot opt in out source destination 735 182K ACCEPT all -- * * 0.0.0.0/0 0.0.0.0/0 Chain fail2ban-ssh (1 references) pkts bytes target prot opt in out source destination 225 16984 RETURN all -- * * 0.0.0.0/0 0.0.0.0/0 2) try to connect from remote machine: $> mysql -u root -p -h x.x.x.x output: timeout.... failed to connect 3) try to add a new rule to iptables: iptables -A INPUT -i eth0 -p tcp -m tcp --dport 3306 -j ACCEPT 4) make sure the new rule is added: $> sudo iptables -nL -v output: Chain INPUT (policy ACCEPT 0 packets, 0 bytes) pkts bytes target prot opt in out source destination 359 25972 fail2ban-ssh tcp -- * * 0.0.0.0/0 0.0.0.0/0 multiport dports 22 251 78665 ACCEPT all -- lo * 0.0.0.0/0 0.0.0.0/0 0 0 REJECT all -- lo * 0.0.0.0/0 127.0.0.0/8 reject-with icmp-port-unreachable 628 64420 ACCEPT all -- * * 0.0.0.0/0 0.0.0.0/0 state RELATED,ESTABLISHED 1 60 ACCEPT tcp -- * * 0.0.0.0/0 0.0.0.0/0 tcp dpt:80 19 988 ACCEPT tcp -- * * 0.0.0.0/0 0.0.0.0/0 tcp dpt:443 1 52 ACCEPT tcp -- * * 0.0.0.0/0 0.0.0.0/0 state NEW tcp dpt:22 0 0 ACCEPT icmp -- * * 0.0.0.0/0 0.0.0.0/0 icmptype 8 5 260 LOG all -- * * 0.0.0.0/0 0.0.0.0/0 limit: avg 5/min burst 5 LOG flags 0 level 7 prefix "iptables denied: " 5 260 REJECT all -- * * 0.0.0.0/0 0.0.0.0/0 reject-with icmp-port-unreachable 0 0 ACCEPT tcp -- eth0 * 0.0.0.0/0 0.0.0.0/0 tcp dpt:3306 Chain FORWARD (policy ACCEPT 0 packets, 0 bytes) pkts bytes target prot opt in out source destination 0 0 REJECT all -- * * 0.0.0.0/0 0.0.0.0/0 reject-with icmp-port-unreachable Chain OUTPUT (policy ACCEPT 0 packets, 0 bytes) pkts bytes target prot opt in out source destination 919 213K ACCEPT all -- * * 0.0.0.0/0 0.0.0.0/0 Chain fail2ban-ssh (1 references) pkts bytes target prot opt in out source destination 359 25972 RETURN all -- * * 0.0.0.0/0 0.0.0.0/0 which appears to be the case (last line in "Chain INPUT" section). 5) try to connect again from remote machine: $> mysql -u root -p -h x.x.x.x output: timeout.... failed to connect which is failing again. 6) try to flush all rules: $> sudo iptables -F 7) this time I CAN CONNECT. 8) reboot server and try to connect, FAILURE. I suspect since the new rule is being appended at the end it will have no effect as there appears to be a "reject all" sort of rule before it. If this is the case, how to make sure the new rule is added in the right order? Otherwise, what am I missing? Please help.

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• Request to server x Reply from server y

  - by klaasio

  I need some advice from you guys: I'm dealing with a custom loadbalancer/software for which we will use 2 main servers and about 8 slave servers. In short: User sends request to main server, main server will receive and handle the requests, sends a request to a slave server and slave server should send data DIRECTLY to the "user". User - Main server Main server - Slave server Slave server - User The reason for which data should be send directly to the user and not through the main server is because of bandwidth and low budget. Now I have the following idea's: -IPinIP, but that is not possible in Layer7 (so far i know there some expensive routers for that) -IP Spoof, using C/C++ we will make it look like the reply came from main server. But I was thinking, perhaps the reply "slave server - User" could just come from a different IP without causing issues in the firewall from the user or his anti-virus. I don't know so well about "home" firewalls/routers and/or anti-virus software. I guess the user machine wouldn't handle it well?

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• Download resume support blocked by isp?

  - by John Doe

  Can ISP block resume support for downloads ? I'm using IDM (internet download manager) to download of the internet from resume supported websites, yet I am unable to resume downloads. I tried different computers with the same result. Turned off firewall, didn't have any effect i was able to download with no issues until a couple of days ago. Another thing i noticed is that before IDM used to try to connect to several connections to speed up my download, but now it can only connect to one connection. Also i tried to download using my vpn, and i was able to download and resume downloads with no problem.

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• Why would one server be sending DUP ACK packets to one PC, which is responding with HTTP RST packets?

  - by IronicMuffin

  I'm not a network profressional, so please excuse any wrong language. I was debugging why my DNS traffic was a constant 160Kbps on our corporate network. I opened up a wireshark trace, and I see one PC of a coworker broadcasting HTTP [RST] packets to one of our DMZ servers at the rate of 1000 a second. He restarted his machine, and as soon as it went offline, the server started broadcasting [DUP] [ACK] packets, until he came back online. It then resumed the HTTP [RST] packets. Apparently this server has been doing this kind of behavior since it went live. I believe it did this with a printer and an access point as well. Can anyone explain why this behavior is occurring? Any solutions? The initial research was done because there have been "bandwidth issues" and I wonder if this is contributing.

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• Testifying that somaxconn change can make a difference

  - by petermolnar

  I got into an argument on the net.core.somaxconn parameter: I was told that it will not make any difference if we change the default 128. I believed this might be enough proof: "If the backlog argument is greater than the value in /proc/sys/net/core/somaxconn, then it is silently truncated to that value" http://linux.die.net/man/2/listen but it's not. So does anyone know a method to testify this with two machines, one running, for example MySQL or LVS and the other is hammering it in a GBit network? I'm opened to any solution, scripts are slightly more welcome.

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• Clients can make maximum only 15 connections to ubuntu custom server

  - by gtan

  I have a custom server in C# being run on Ubuntu 9 under mono. I can make up to 15 silverlight clients connect to the server. When I make the 16th, it just waits. And if I close one of the established connections, the 16th client is able to connect. I am making the connections from one machine. I am also not exceeding any file handle limit. The limit is 1024 and I am having around 300. Any ideas how to make more connections? Also why the number 15? Is it something linux-specific? EDIT: I have run the same server on an Ubuntu 11.10 virtual machine and was able to make more than 15 connections. I presume it's a configuration problem on the Ubuntu 9 machine then. Any help on that?

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• ActiveMQ - "Cannot send, channel has already failed" every 2 seconds?

  - by quanta

  ActiveMQ 5.7.0 In the activemq.log, I'm seeing this exception every 2 seconds: 2013-11-05 13:00:52,374 | DEBUG | Transport Connection to: tcp://127.0.0.1:37501 failed: org.apache.activemq.transport.InactivityIOException: Cannot send, channel has already failed: tcp://127.0.0.1:37501 | org.apache.activemq.broker.TransportConnection.Transport | Async Exception Handler org.apache.activemq.transport.InactivityIOException: Cannot send, channel has already failed: tcp://127.0.0.1:37501 at org.apache.activemq.transport.AbstractInactivityMonitor.doOnewaySend(AbstractInactivityMonitor.java:282) at org.apache.activemq.transport.AbstractInactivityMonitor.oneway(AbstractInactivityMonitor.java:271) at org.apache.activemq.transport.TransportFilter.oneway(TransportFilter.java:85) at org.apache.activemq.transport.WireFormatNegotiator.oneway(WireFormatNegotiator.java:104) at org.apache.activemq.transport.MutexTransport.oneway(MutexTransport.java:68) at org.apache.activemq.broker.TransportConnection.dispatch(TransportConnection.java:1312) at org.apache.activemq.broker.TransportConnection.processDispatch(TransportConnection.java:838) at org.apache.activemq.broker.TransportConnection.iterate(TransportConnection.java:873) at org.apache.activemq.thread.PooledTaskRunner.runTask(PooledTaskRunner.java:129) at org.apache.activemq.thread.PooledTaskRunner$1.run(PooledTaskRunner.java:47) at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886) at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908) at java.lang.Thread.run(Thread.java:662) Due to this keyword InactivityIOException, the first thing comes to my mind is InactivityMonitor, but the strange thing is MaxInactivityDuration=30000: 2013-11-05 13:11:02,672 | DEBUG | Sending: WireFormatInfo { version=9, properties={MaxFrameSize=9223372036854775807, CacheSize=1024, CacheEnabled=true, SizePrefixDisabled=false, MaxInactivityDurationInitalDelay=10000, TcpNoDelayEnabled=true, MaxInactivityDuration=30000, TightEncodingEnabled=true, StackTraceEnabled=true}, magic=[A,c,t,i,v,e,M,Q]} | org.apache.activemq.transport.WireFormatNegotiator | ActiveMQ BrokerService[localhost] Task-2 Moreover, I also didn't see something like this: No message received since last read check for ... or: Channel was inactive for too (30000) long Do a netstat, I see these connections in TIME_WAIT state: tcp 0 0 127.0.0.1:38545 127.0.0.1:61616 TIME_WAIT - tcp 0 0 127.0.0.1:38544 127.0.0.1:61616 TIME_WAIT - tcp 0 0 127.0.0.1:38522 127.0.0.1:61616 TIME_WAIT - Here're the output when running tcpdump: Internet Protocol Version 4, Src: 127.0.0.1 (127.0.0.1), Dst: 127.0.0.1 (127.0.0.1) Version: 4 Header length: 20 bytes Differentiated Services Field: 0x00 (DSCP 0x00: Default; ECN: 0x00: Not-ECT (Not ECN-Capable Transport)) 0000 00.. = Differentiated Services Codepoint: Default (0x00) .... ..00 = Explicit Congestion Notification: Not-ECT (Not ECN-Capable Transport) (0x00) Total Length: 296 Identification: 0x7b6a (31594) Flags: 0x02 (Don't Fragment) 0... .... = Reserved bit: Not set .1.. .... = Don't fragment: Set ..0. .... = More fragments: Not set Fragment offset: 0 Time to live: 64 Protocol: TCP (6) Header checksum: 0xc063 [correct] [Good: True] [Bad: False] Source: 127.0.0.1 (127.0.0.1) Destination: 127.0.0.1 (127.0.0.1) Transmission Control Protocol, Src Port: 61616 (61616), Dst Port: 54669 (54669), Seq: 1, Ack: 2, Len: 244 Source port: 61616 (61616) Destination port: 54669 (54669) [Stream index: 11] Sequence number: 1 (relative sequence number) [Next sequence number: 245 (relative sequence number)] Acknowledgement number: 2 (relative ack number) Header length: 32 bytes Flags: 0x018 (PSH, ACK) 000. .... .... = Reserved: Not set ...0 .... .... = Nonce: Not set .... 0... .... = Congestion Window Reduced (CWR): Not set .... .0.. .... = ECN-Echo: Not set .... ..0. .... = Urgent: Not set .... ...1 .... = Acknowledgement: Set .... .... 1... = Push: Set .... .... .0.. = Reset: Not set .... .... ..0. = Syn: Not set .... .... ...0 = Fin: Not set Window size value: 256 [Calculated window size: 32768] [Window size scaling factor: 128] Checksum: 0xff1c [validation disabled] [Good Checksum: False] [Bad Checksum: False] Options: (12 bytes) No-Operation (NOP) No-Operation (NOP) Timestamps: TSval 2304161892, TSecr 2304161891 Kind: Timestamp (8) Length: 10 Timestamp value: 2304161892 Timestamp echo reply: 2304161891 [SEQ/ACK analysis] [Bytes in flight: 244] Constrained Application Protocol, TID: 240, Length: 244 00.. .... = Version: 0 ..00 .... = Type: Confirmable (0) .... 0000 = Option Count: 0 Code: Unknown (0) Transaction ID: 240 Payload Content-Type: text/plain (default), Length: 240, offset: 4 Line-based text data: text/plain [truncated] \001ActiveMQ\000\000\000\t\001\000\000\000<DE>\000\000\000\t\000\fMaxFrameSize\006\177<FF><FF><FF><FF> <FF><FF><FF>\000\tCacheSize\005\000\000\004\000\000\fCacheEnabled\001\001\000\022SizePrefixDisabled\001\000\000 MaxInactivityDurationInitalDelay\006\ It is very likely a tcp port check. This is what I see when trying telnet from another host: 2013-11-05 16:12:41,071 | DEBUG | Transport Connection to: tcp://10.8.20.9:46775 failed: java.io.EOFException | org.apache.activemq.broker.TransportConnection.Transport | ActiveMQ Transport: tcp:///10.8.20.9:46775@61616 java.io.EOFException at java.io.DataInputStream.readInt(DataInputStream.java:375) at org.apache.activemq.openwire.OpenWireFormat.unmarshal(OpenWireFormat.java:275) at org.apache.activemq.transport.tcp.TcpTransport.readCommand(TcpTransport.java:229) at org.apache.activemq.transport.tcp.TcpTransport.doRun(TcpTransport.java:221) at org.apache.activemq.transport.tcp.TcpTransport.run(TcpTransport.java:204) at java.lang.Thread.run(Thread.java:662) 2013-11-05 16:12:41,071 | DEBUG | Transport Connection to: tcp://10.8.20.9:46775 failed: org.apache.activemq.transport.InactivityIOException: Cannot send, channel has already failed: tcp://10.8.20.9:46775 | org.apache.activemq.broker.TransportConnection.Transport | Async Exception Handler org.apache.activemq.transport.InactivityIOException: Cannot send, channel has already failed: tcp://10.8.20.9:46775 at org.apache.activemq.transport.AbstractInactivityMonitor.doOnewaySend(AbstractInactivityMonitor.java:282) at org.apache.activemq.transport.AbstractInactivityMonitor.oneway(AbstractInactivityMonitor.java:271) at org.apache.activemq.transport.TransportFilter.oneway(TransportFilter.java:85) at org.apache.activemq.transport.WireFormatNegotiator.oneway(WireFormatNegotiator.java:104) at org.apache.activemq.transport.MutexTransport.oneway(MutexTransport.java:68) at org.apache.activemq.broker.TransportConnection.dispatch(TransportConnection.java:1312) at org.apache.activemq.broker.TransportConnection.processDispatch(TransportConnection.java:838) at org.apache.activemq.broker.TransportConnection.iterate(TransportConnection.java:873) at org.apache.activemq.thread.PooledTaskRunner.runTask(PooledTaskRunner.java:129) at org.apache.activemq.thread.PooledTaskRunner$1.run(PooledTaskRunner.java:47) at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886) at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908) at java.lang.Thread.run(Thread.java:662) 2013-11-05 16:12:41,071 | DEBUG | Unregistering MBean org.apache.activemq:BrokerName=localhost,Type=Connection,ConnectorName=ope nwire,ViewType=address,Name=tcp_//10.8.20.9_46775 | org.apache.activemq.broker.jmx.ManagementContext | ActiveMQ Transport: tcp:/ //10.8.20.9:46775@61616 2013-11-05 16:12:41,073 | DEBUG | Stopping connection: tcp://10.8.20.9:46775 | org.apache.activemq.broker.TransportConnection | ActiveMQ BrokerService[localhost] Task-5 2013-11-05 16:12:41,073 | DEBUG | Stopping transport tcp:///10.8.20.9:46775@61616 | org.apache.activemq.transport.tcp.TcpTranspo rt | ActiveMQ BrokerService[localhost] Task-5 2013-11-05 16:12:41,073 | DEBUG | Initialized TaskRunnerFactory[ActiveMQ Task] using ExecutorService: java.util.concurrent.Threa dPoolExecutor@23cc2a28 | org.apache.activemq.thread.TaskRunnerFactory | ActiveMQ BrokerService[localhost] Task-5 2013-11-05 16:12:41,074 | DEBUG | Closed socket Socket[addr=/10.8.20.9,port=46775,localport=61616] | org.apache.activemq.transpo rt.tcp.TcpTransport | ActiveMQ Task-1 2013-11-05 16:12:41,074 | DEBUG | Forcing shutdown of ExecutorService: java.util.concurrent.ThreadPoolExecutor@23cc2a28 | org.apache.activemq.util.ThreadPoolUtils | ActiveMQ BrokerService[localhost] Task-5 2013-11-05 16:12:41,074 | DEBUG | Stopped transport: tcp://10.8.20.9:46775 | org.apache.activemq.broker.TransportConnection | ActiveMQ BrokerService[localhost] Task-5 2013-11-05 16:12:41,074 | DEBUG | Connection Stopped: tcp://10.8.20.9:46775 | org.apache.activemq.broker.TransportConnection | ActiveMQ BrokerService[localhost] Task-5 2013-11-05 16:12:41,902 | DEBUG | Sending: WireFormatInfo { version=9, properties={MaxFrameSize=9223372036854775807, CacheSize=1024, CacheEnabled=true, SizePrefixDisabled=false, MaxInactivityDurationInitalDelay=10000, TcpNoDelayEnabled=true, MaxInactivityDuration=30000, TightEncodingEnabled=true, StackTraceEnabled=true}, magic=[A,c,t,i,v,e,M,Q]} | org.apache.activemq.transport.WireFormatNegotiator | ActiveMQ BrokerService[localhost] Task-5 So the question is: how can I find out the process that is trying to connect to my ActiveMQ (from localhost) every 2 seconds?

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• LDAP socket keep-alive

  - by Dmitry Khalatov

  We are using OpenLDAP client library to conect to an LDAP server. The problem is that if there is no activity for some time, server (or firewall in the middle) drops TCP connection. Our current implementation of "keep-alive" just does search for baseDN from time to time - any better ideas ?

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• What is the equivalent to WinSock in the iPhone SDK?

  - by Jason

  I need to communicate with a hardware device using TCP and with Windows I would use WinSock. What is the equivalent library that I can use from the iPhone SDK?

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• Finding a dll whose CLSID is known

  - by deostroll

  I've downloaded the w3sockets. Primarily using for trying to do telnet via an application. So far we've been experimenting with vbscript. In vbscript we do something like: Set socket = CreateObject("Socket.Tcp") I am trying to use this for a .net application. I need to know the dll it is hosted in. Anyway I can find this?

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• TTCPServer limited to 10 connections?

  - by Stijn Sanders

  I've created a TCP server NT-Service in Delphi 6, I've tried Indy components, Ararat Synapse components, and am now trying just plain old TTcpServer to see which would perform best while using the least resources. I'm surprised to see that the live instance of the service (running on Windows Server) is still limited to 10 connections! Any new connections are forcibly disconnected. Have I missed something? Do I need to set a property or override a method of TCustomTcpServer?

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• Enable RFC1323 on a per socket basis in Windows?

  - by Sheado

  Howdy.. Anybody know if it's possible to enable RFC1323 on a per TCP socket basis in windows? I know it can be changed system wide via the registry ( http://www.psc.edu/networking/projects/tcptune/OStune/winxp/winxp_stepbystep.html ) Also, it seems like this is possible *nix via: int on=1; setsockopt(s,IPPROTO_TCP,TCP_RFC1323,&on,sizeof(on)); Is there a Windows equivalent? Thanky much!

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• SQL Server: error when connecting

  - by atricapilla

  The application I'm using tries to connect SQL Server named instance running on a dedicated database server. Here's the error I'm getting: The TCP/IP connection to the host <instance_name>, port 1433 has failed. Error: Connection refused: connect. Is the firewall blocking my access or what? Should I dedicate a different port for this application?

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• Other than UDP Broadcast or Multicast, what other methods can I use on a WiFI network to discover co

  - by Gubatron

  I've implemented a simple ping/pong protocol to discover other computers connected to the same WiFI router. This works fine on many routers, but it seems some public routers have UDP traffic blocked or disabled. What other options do I have to discover the computers connected to the router? I was thinking of brute forcing TCP attempts (trying to open connections to all possible IPs on my subnetwork) but this would be very costly and I would have to cycle several times and still not find every machine that's recently connected to the network.

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• How to make from your Custom HTTP Module a stand alone HTTP server?

  - by Ole Jak

  How to make from your Custom HTTP Module a stand aloun TCP\HTTP server capable of for example runing near to any other HTTP server (on same port, just taking some URL namespace like www.example.com/myModule/blabla?id=anyID, and not beeng rood to my other servers like apache HTTP server with PHP (so I can steel call it www.example.com/myApach/blabla?id=anyID) and with my other C\C++ based servers.)? I need CODE examples...)

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• How to implement a hub in Python

  - by j3d

  Dear all, I need to implement a TCP server in Python which receives some data from a client and then sends this data to another client. I've tried many different implementations but no way to make it run. Any help would be really appreciated.

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• Uncatchable errors in node.js

  - by Peter Burns

  So I'm trying to write a simple TCP socket server that broadcasts information to all connected clients. So when a user connects, they get added to the list of clients, and when the stream emits the close event, they get removed from the client list. This works well, except that sometimes I'm sending a message just as a user disconnects. I've tried wrapping stream.write() in a try/catch block, but no luck. It seems like the error is uncatchable.

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• length of captured packets more than MTU

  - by kumar

  Hi, I m running iperf between two machines (linux) and I can observe the mtu of both the interfaces connected is 1500. I ran tcpdump to capture packets and I observed some packets have "length as 2962"....how come this is possible with mtu as only 1500? Please clarify. Thanks! Note: flags field is set as DF. and proto is TCP

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• L-Soft LISTSERV TCPGUI Interface for PHP Creation

  - by poolnoodl

  I'm trying to use LISTSERV's "API" in PHP. L-Soft calls this TCPGUI, and essentially, you can request data like over Telnet. To do this, I'm using PHP's TCP socket functions. I've seen this done in other languages but can't quite convert it to PHP. I can connect, I can change set ASCII or BINARY mode. But I can never quite craft the header packet the way I need to authenticate, so I'm thinking I'm messing up my conversion. C: http://www.lsoft.com/manuals/16.0/htmlhelp/advanced%20topics/TCPGUI.html#2334328 $origin = '[email protected]'; $pwd = 'password'; $host = "example.com"; $port = 2306; $email = "[email protected]"; $list = "mailinglist"; $command = "Query $list FOR $email"; $fp = stream_socket_client("tcp://$host:$port", $errno, $errstr, 30); $cmd = $command . " PW=" . $pwd; $len = strlen($cmd); $orglen = strlen($origin); $n = $len + $orglen + 1; $headerPacket[0] = "1"; $headerPacket[1] = "B"; $headerPacket[2] = "\r"; $headerPacket[3] = "\n"; $headerPacket[4] = ord($n / 256); $headerPacket[5] = ord($n + 255); $headerPacket[6] = ord($orglen); for ($i = 0; $i < $orglen; $i++) { $headerPacket[$i + 7] = ord($origin[$i]); } for ($i = 0; $i < $len; $i++) { $cmdPacket[$i] = ord($cmd[$i]); } fwrite($fp, implode($headerPacket)); while (!feof($fp)) { echo fgets($fp, 1024); } Any thoughts on where I'm going wrong? I'd much appreciate it if anyone could point me toward some code to do this, days of googling and searching here on SO has only lead me to examples in other languages. Of course, if you know C (or Java or Perl as linked below in my comment to bypass the spam filter), PHP, and socket programming fairly well, you could probably rewrite the whole of the code in an hour, maybe a few minutes. You'd have my eternal thanks for that.

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• Will EAGAIN return on send for anything other than buffer full?

  - by jkg0

  If I use send() on a non-blocking tcp socket in Linux will it return EAGAIN for anything other than a send buffer full condition? I basically need to decide if I want to use the socket send buffer as the only buffer for my app or if I need my own user space buffer to feed the socket buffer.

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• WSDL vs DLL. Which is better?

  - by Lopper

  I would like to create a reusable interface to transfer some proprietary information over the TCP/IP connection. If given only the choice of either WSDL or DLL, what are the pros and cons of using each? This is assuming that Windows OS is used.

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• How to send stream data via Bluetooth from an iPhone/iPod Touch to a Windows C++ application?

  - by PLinhol

  Hello, I need to develop an iPhone/iPod Touch application that creates a server to send some data stream (characters or bytes) to a Windows C++ application via Bluetooth. I'm thinking of creating a TCP connection, but don't know where to start. What iPhone API should I use do to something like this? Does anyone knows some code examples that i can use to do this? And in Windows, what should I use to support this kind of communication? Thanks

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• How to find out when to increase bit rate? (TCP streaming solution)

  - by Kabumbus

  How to find out when to increase bit rate? (TCP streaming solution) We have a stream with "frames". each "frame" has a "timestamp" . frames have bit rate property which is actually there size. We generate frames with our app and stream them one by one on to our TCP server socket. At the same time server post replies so when after each sent frame we try to read from socket we receive which timestamp is currently on server. if timestamp is lover than previous frame we lover bit rate 20%. Such scheme seems to work giving me one way vbr (lowering) but I wonder how to implement increase? I mean we can always try to increase 5% each frame until some limited desired value but each time we have delay will lose real-time feature of our stream... Generally such scheme is for finding out how much of network stream is currently used by other user apps and give picture of how much server is loaded at the same time so we can stream just right amount of data for all to receive it in real time. So what shall I do to add increase to my scheme? So having current bit rate of A I thought we could add +7% for 3 frames and than one -20% and than if all that 3 frames with +7% came in time we could add 14% to A and repeat circle and it would hopefully not be really noticeable if 2nd frame wold come to us with delay... probably this one is too localised because it is a requirement for me to use TCP.

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• Webmin and/or port 10000 not working

  - by DisgruntledGoat

  I've recently installed Webmin on a Ubuntu server but I can't get it to work. I asked a recent question about saving iptables but it turns out you don't need to "save" iptables changes. Anyway, I still can't get Webmin working after opening the port up: iptables -A INPUT -p tcp -m tcp --dport 10000 -j ACCEPT It seems that either the command is not opening up port 10000, or there is a separate problem with Webmin. If I run iptables -L I see lines like the following, but no port 10000: ACCEPT tcp -- anywhere anywhere tcp dpt:5555 state NEW ACCEPT tcp -- anywhere anywhere tcp dpt:8002 state NEW ACCEPT tcp -- anywhere anywhere tcp dpt:9001 state NEW However, there is a line: ACCEPT tcp -- anywhere anywhere tcp dpt:webmin Any ideas why Webmin is not working? The IP address works fine and we can view web sites on the server, but https://[ip]:10000/ (or http) doesn't work.

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