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Questions tagged [tcp]

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.

TCP is just one communications protocol on the web. Others include:

  • User Datagram Protocol (UDP)
  • Internet Control Message Protocol (ICMP)
  • Hypertext Transfer Protocol (HTTP)
  • Post Office Protocol (POP3)
  • File Transfer Protocol (FTP)
  • Internet Message Access Protocol (IMAP)

TCP on Wikipedia

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haproxy + stunnel + keep-alive?

I'd like to put stunnel in front of haproxy 1.4 to handle HTTPS traffic. I also need stunnel to add the X-Forwarded-For header. This can be achieved by the "stunnel-4.xx-xforwarded-for.diff" patches from the haproxy website. However, the…
Chris Lercher
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better TCP performance over a “high delay network”

I’m trying to improve my TCP throughput over a “high delay network” between Linux machines. I set tcp_mem, tcp_wmem and tcp_rmem to “8192 7061504 7061504”. I set rmem_max, wmem_max, rmem_default and wmem_default to “7061504”. I set…
Gil
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lots of packets pruned and packets collapsed because of socket buffer low/overrun

i've set up a test machine (debian squeeze 2.6.32 on a linode 2048 machine) that interact with an api that returns large chunks of json. It calls the API 3000/minutes asynchronously, the api is returning payloads of ~450kb. There's also an http…
hellvinz
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How do I dump raw data from a TCP port in Windows using the netsh command?

I have an apparently simple issue which is proving very difficult to find an answer for. The site has a highly-secured Windows Server 2019 installation and an appliance connected to it running on a certain TCP port. I need a sample of the raw data…
Ruslan
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tcpdump capture new connections only

I am using tcpdump to capture traffic from specific IP address. Is there the possibility to capture new connections only, meaning TCP streams that start with SYN packet?
Ania Katzenelson
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Higher TCP latencies in the latest versions of Linux

In my research group, we recently upgraded the OS on our machines from Red Hat 6.2 to Debian 8.3 and observed that the TCP round trip time through the integrated Intel 1G NICs between our machines had doubled from about 110µs to 220µs. At first, I…
Stephen
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Proxying TCP by hostname

I've got multiple game servers TCP ports on my single host machine. The goal is to have users be able to connect to server1.domain.net and have their directed based on that subdomain. My first instinct wrote the following but then I realised that…
shaun m
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TCP packet being retransmitted 7 times when sysctl tcp_retries1 is set to 3 - why?

Ubuntu 12.04 I am trying to better understand how many times TCP will attempt to retransmit a packet when it does not receive confirmation the destination received it. After reading the tcp man page it seemed clear this is controlled by the sysctl…
HodB
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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 12.04.4 (3.11.0-17-generic) and machine B is running…
user133831
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Root cause of "curl: (56) SSL read: errno -5961" errors

I was evaluating some SSL failures, and noticed that when I use curl to one of the failing sites, I got curl: (56) SSL read: errno -5961; however, my google queries for that error didn't show the reason for the openssl failure. Question: What does…
Mike Pennington
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Many dropped packets of my NIC

I have a server running on CentOS 5.3 (a comet chat server, will have lots of tcp connections). Recently I found it was very slow (http service and ssh) so I use "ifconfig" command to figured out what happened. eth0 Link encap:Ethernet HWaddr…
Mickey Shine
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Unexpectedly shrunk window

I run a major media upload/download site and I noticed these: Is this serious or background noise due to the big file sizes and is there any tweaks I can add to /etc/sysctl.conf to improve and prevent issues? [8822139.804040] TCP: Peer…
Jason
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Why does WireShark think this frame is a TCP segment of a reassembled PDU

Please find a small pcap file here illustrating my problem. I have a three-way TCP handshake, followed by two FIX logons. (FIX is a protocol used in trading.) The first FIX logon (frame 4) is interpreted and parsed just fine by WireShark, but the…
Randomblue
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Lower TCP throughput from 1Gbps server than 100Mbps server over large RTT

We've got infrastructure distributed in a few major locations around the world - Singapore, London and Los Angeles. The RTT between any two locations is over >150ms. We've recently upgraded all of the servers to use 1Gbps links (from 100Mbps). We've…
Sam
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Where can I embed proprietary information in a layer 2 or layer 3 packet?

The Citrix Netscaler has an interesting property that embeds information in the TCP packet that gets sent to the host. This property is echoed back to the Netscaler in such a way that the Netscaler can use this to determine which Virtual Server,…
makerofthings7
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