TCP stands for Transmission Control Protocol and is one of the core protocols of the Internet Protocol Suite. TCP complements the Internet Protocol (IP), and therefore the entire suite is commonly referred to as TCP/IP.

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Improving TCP performance over a gigabit network lots of connections and high traffic for storage and streaming services

I have two servers, Both servers hardware Specification are Processor : Dual Processor RAM : over 128 G.B Hard disk : SSD Hard disk Outging Traffic bandwidth : 3 Gbps network cards speed : 10 Gbps ...
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352 views

How to send 0x80 byte to a tcp port using netcat or similar tool?

I'm trying to make a Memcached server respond as if I where using binary protocol. If possible just command line answers pls, no code spinet in any programming language.
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1answer
57 views

TCP Server Memory management: #Connections Vs. #Requests

Given that, there is no theoretical limit to number of concurrent TCP connections a Windows 2008 server can handle. Only thing will happen is, with each connection there will be memory consumption in ...
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29 views

Security concerns regarding php://stdin

I'm using xinet.d and php://stdin to host a raw tcp-connnection, (following the excellent guide at http://gonzalo123.com/2010/05/23/building-network-services-with-php-and-xinetd/) I'm concerned with ...
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1answer
201 views

How to measure TCP connection time in Linux

I want to measure the overhead in creating a TCP connection. I know of many tools like hping and netperf, but they seem oriented at measuring latency. I want to know how long the 3-way handshake ...
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1answer
2k views

Why would a client send a RST packet as reply to a SYN,ACK?

I have a HTTP webservice where sometimes the connection setup fails in a strange way: client sends a SYN packet server sends a SYN,ACK reply client responds with RST In which situations could a ...
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2answers
2k views

Wireshark TCP Window Size Value

I am debugging an application with Wireshark and watching the TCP Window Size value shrink on one side of the communication. If the packet's TCP section shows a "Window size value: 1", does that mean ...
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3answers
248 views

What happen when I assign 2 IP on one NIC? [closed]

What happen when I assign 2 IP on one NIC? e.g. I have one physical NIC (eth0) and I assign on this interface 2 IPs from different network. e.g. auto eth0 iface eth0 inet static address ...
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1answer
1k views

Connecting To FMS Server Issues

I am trying to get my computer to connect to an Adobe Connect server but I have had no luck. The error that Adobe is telling me is "ERROR: FMS Server did not return correctly!" and have done some ...
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67 views

Network flooded with LLC packet

Recently my network has been slow. From Tcpdump i found lot of frame with protocol LLC. A complete packet capture can been here tcpdump result Any hints on interpreting these packet?
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6answers
26k views

Finding cause of TCP retransmission within a LAN

Hello denizens of Server Fault I have an irritating problem with a LAN of about 100 computers, 2 Windows domain servers, and 12 VoIP phones. Since their installation around a year ago, every week or ...
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2answers
355 views

block all packets in windows 7 (so nothing appears in wireshark)? Can anything locally installed do it?

is it possible to block all packets in windows 7, so that nothing appears in wireshark? I have tried choosing Block all for incoming. for outgoing, I see it has no block all option, just a block ...
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2answers
105 views

TCP Python Server

I have a question regarding connection reliability running a tcp server from an ec2 instance. We are currently serving mobile customers around the world from the Oregon region using a c3.4xl ec2 ...
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1answer
672 views

TCP Sequence & Acknowledgment numbers

I have looked through other questions on here involving the relevant topics, but I am still not clear on this. I have just been reading this explanation of TCP sequence & acknowledgment numbers. ...
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2answers
193 views

apache2 keepalive and opening a tcp connection

An IP packet contains a payload, such as HTTP information, which in turn contains html information. An IP packet is encapsulated into a TCP segment, which detects problems in transmission over ...
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2answers
385 views

What are possible downsides to setting a (very) large initcwnd for high-bandwidth connections?

I have been experimenting with the TCP parameters in Linux (with a 3.5 kernel). Basically concerning this connection: Server: Gigabit uplink in datacenter, actual bandwidth (due to sharing uplinks) ...
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3answers
171 views

Is TCP header the same as TCP segment?

So, is a TCP header actually the same thing as a TCP segment? I was reading this page, where it reads near the end that: Even though it might seem they are, in most cases, when referring to the ...
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1answer
321 views

Connect to sphinx on remote server

I recently moved sphinx onto the same server as our db so our architecture is: File Server that hosts our web app DB server w/ Sphinx instance (searchd) When I try to connect to sphinx at ...
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1answer
363 views

TCP Window size increases drastically and sender don't send until the receive buffer is not empty

I have a download stream over TCP in an application (running on Win2k12). The problem is that the connection gets closed by the sender because it times out. I used wireshark to see what happens on ...
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1answer
152 views

Increase number of connections per socket

How do I increase the number of connections each socket can accept? I know that you can increase the total number of connections using: # sysctl kern.ipc.somaxconn=4096 But each connection is then ...
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2answers
155 views

FreeBSD Established Connections Maxing out at 300

We've previously had issues in our environment where it seemed we were reaching FreeBSDs max connection limit. We took action demonstrated by http://nginx.org/en/docs/freebsd_tuning.html and bumped up ...
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1answer
787 views

TCP Zero windows size and full windows size

The problem that we are facing is that some of the http connection have response time > 60s (about 5%). I discover that the problem should between the web server and loadbalancer. Here is my finding, ...
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0answers
19 views

Debian as TCP-Server for Serial Port redirecting [duplicate]

I want to start a tcp listener on debian. One client should be able to connect and should get inputs of serial port in the tcp connection. And when the client sends data through the tcp socket the ...
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1answer
4k views

Too many TCP connections causes disconnections

I have a game server which runs with TCP connections. Server disconnects users randomly. I think its related with TCP settings of server. In local development environment written code can handle ...
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0answers
391 views

What does “connections reset due to unexpected data” in netstat -s mean

I'm running a memcached server under heavy load from multiple web servers. While investigating some odd app level behaviour, we spotted that netstat -s on the memcached box was showing a lot of ...
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0answers
255 views

TCP connection timeouts that persist - listener queue backlog?

I have an app running on AIX 6.1 that has a single server process that listens for and polls tcp connections and simply forwards on messages to another process using an IPC message queue. It's been ...
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271 views

Keep doing TCP Retransmission with ACK, PSH

here is my situation: I got two servers, a loadbalancer (prowered by softlayer) and a web server running apache 2.2 and php 5.4. My web application only serve android mobile device. I was tested 2 set ...
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2answers
37 views

Distributed LAMP vs DB and Web Server same box

We have a very read heavy semantic web (RDF) application which is RHEL 5/Apache 2.2.3/Tomcat 6/Java 6 on one Server, and MySQL 5.1 on another. Apache and MySQL are backported Red Hat repo stuff, so ...
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1answer
144 views

Low throughput on Debian + nginx/apache

On the same LAN/WAN I have a Windows server 2012 server running IIS 7.5 and a Debian (wheezy) server running Nginx 1.4.5. Both servers are connected to the same LAN/WAN. When I download a 10mb file ...
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87 views

Reproduce netperf TCP_RR test with NTttcp

The documentation of NTttcp being hard to find and to understand, how can I mimic the behavior of the TCP_RR netperf test with NTttcp?
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1answer
96 views

Linux tool to show connections/s?

Is there a tool/command to show connections per sec? I've tried a few iptraf and iftop but I can't see anything about connection rates.
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1answer
85 views

TCP timestamps field is in the future

I have a server sending TCP packets. I noticed, with wireshark, that my packets in the Timestamp optional field look like Timestamps: TSval 2552765291, TSecr 3858527953 The TSval is the value my ...
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321 views

iperf test in reverse direction gives different result

I used iperf to measure the max throughput for TCP connection between two ubuntu machines. Both the machines were directly connected be means of a 1Gbps cable. When I performed iperf tests i obtained ...
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1answer
99 views

Support of batch mode in tcpkill

I fire tcpkill with destination ip. Example tcpkill host 10.0.2.184 The problem I am facing is that, tcpkill doesn't come out after killing all tcp connection. After killing all tcp connection it ...
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1answer
155 views

Show real TCP/IP addresses behind Nginx environment

When i execute the command netstat -atun | awk '{print $5}' | cut -d: -f1 | sed -e '/^$/d' |sort | uniq -c | sort -n I see high number of connection assigned to server ip I want to see the real ...
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1answer
72 views

Open file count keeps increasing forever

I'm experiencing issues with the number of files opened increasing over time. If I run my server for about few hours, it'll no more accept any connections. The limit was 1024. I've increased the limit ...
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1answer
1k views

Windows Server 2008 TCP connections limit

I run my own game server made in .net 4.5 on a Windows Web Server 2008 VPS. I have done some research on a problem I have. My app doesn't accept clients, if there are already 1000 clients connected. ...
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0answers
345 views

No response to some SYN packets when timestamps are enabled

I have a TCP server listening on a machine ("the server") running Ubuntu 12.04.3 (kernel 3.8.0-31-generic). It receives connections from 2 different client machines. Machine A is running Ubuntu ...
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3answers
556 views

Windows Server TCP sockets random disconnect: how to reproduce?

We rented 10 Windows servers from a large provider in Europe. They all work as expected. One server suddenly crashed and customer care found that both disks were broken. They replaced disks and also ...
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217 views

Linux MIPS box: ICMP (ping) works, but TCP does not - how to fix it?

I'm trying to set up MIPS Linux box network. Here is it's configuration: ~ # ifconfig eth0 Link encap:Ethernet HWaddr CC:5D:4E:FF:45:7F inet addr:192.168.0.2 Bcast:192.168.0.255 ...
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6answers
838 views

How can I find the total number of TCP connections for a given port and period of time by IP?

On a Linux system there are plenty of methods for listing the current TCP connections for a given port by connecting IP but: how can I count the total number of connections to a port per source IP for ...
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2answers
2k views

VMXNET3 performance on Linux on ESX 5.0

What kind of performance can I expect from VMXNET3 adapter when running two Linux guests on the same VMware ESX private network defined between those guests? I use VMXNET3 adapter for communicating ...
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143 views

How can I replay a TCP stream to my client

I need to do some validation testing of a new feed handler I have made. I have some pcap data that I captured from the production network and I would like to have my development feed handler connect ...
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4answers
8k views

Karmic Koala (Ubuntu): enable remote x clients through TCP

It seems every version of Ubuntu has a different way to enable remote connections to the local X server. I'm asking this question, while I do my own research: how can I enable the X server listening ...
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3answers
3k views

Allow X Client Display through TCP on Lucid

On Karmic, to allow other PCs to open and X-Window on a station, one had to edit /etc/gdm.conf and change DisallowTCP to false. That file no longer exists on Lucid. I tried changing an entry in ...
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1answer
70 views

TCP echo server security [closed]

I am setting up a Linux server similar to a TCP echo server and am wondering about security issues I should be concerned about. This will be a bare bones Centos/KDE server with no additional files ...
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1answer
58 views

What is the incentive to operate a TCP/IP node? [closed]

I mean, why does anybody relay messages to other nodes? Why are these eleven good people below helping me send my bytes to their destination? traceroute to stackoverflow.com (198.252.206.140), ...
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1answer
76 views

Default TCP connection backlog value in Windows

Which is the default connection backlog value for TCP in Windows? I have tried to find it but no luck. Cheers
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1answer
109 views

Port scanning from localhost

I see lot of tcp connections on different ports on my server with 'TIME_WAIT' status. Just simple port scan, but i cant see ip address of this bastard because connections is going from my nginx. Can ...
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3answers
522 views

How can private IPV4 addresses get past iptables NAT (tcp RST,FIN)

I've got a router performing simple NAT translation using iptables iptables -t nat -o -j MASQUERADE This works fine almost all of the time except for one particular case where some TCP RST and FIN ...