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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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apache webserver unresponsive with server-status showing all child processes waiting for connection

My setup: I have 3 nearly identical webserver machines serving the same high loaded dynamic website with simple load balancing over dns. The service has been working for over two years with the same apache config: apache2, php5, ubuntu 8.04 linux…
Jeff
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What are the ramifications of setting tcp_tw_recycle/reuse to 1?

I set both tcp_tw_recycle/reuse to 1 in my configuration file. What are the ramifications of doing this? If a tcp socket is re-used, does that pose a security risk? i.e. 2 different connections both potentially being able to send data in? Is it…
codecompleting
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How to kill a TCP connection using tcpkill utility

I'm trying to kill an ESTABLISHED TCP connection using tcpkill. The connection is an open HTTPS connection. It appears on netstat as: tcp 0 0 X.X.X.X:55601 X.X.X.X:https ESTABLISHED So, as per the man page, I enter: $…
Charles Salvia
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Automatically-reconnecting TCP tunnel

I have an unreliable network connection between two machines: sometimes active TCP connections get dropped for reasons beyond my control. I want to establish a reliable TCP connection between the two machines. If the network was reliable, I'd just…
Gilles 'SO- stop being evil'
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More than 65536 TCP connections on Linux

I'm stuck trying to setup more than 65536 outgoing TCP connections from a Linux (RedHat5) box. I have already configured both outgoing and accepting boxes to allow enough file descriptors. I don't believe there is a problem on the accepting side - I…
NickB
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How to configure iptables so an unwanted port is not reported as filtered

I'd like to stop others from seeing my ports as filtered in the nmap standard scan (unprivileged). Let's say that I have the following ports open: 22, 3306, 995 and a firewall configured like this: -A INPUT -p tcp -m tcp --dport 22 -j DROP -A INPUT…
user3125731
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How to fine tune TCP performance on Linux with a 10Gb fiber connection

We have 2 Red Hat servers that are dedicated for customer speedtest. They both use 10Gb fiber connections and sit on 10Gb links. All network gear in between these servers fully support 10Gb/s. Using Iperf or Iperf3 the best I can get is around…
user53029
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Simulate slow connection between two ubuntu server machines

I want to simulate the following scenario: given that I have 4 ubuntu server machines A,B,C and D. I want to reduce the network bandwidth by 20% between machine A and machine C and 10% between A and B. How to do this using network…
Yahia
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What does TCP: too many orphaned sockets mean?

When I use dmesg to look at linux kernel messages, I see a flood of.... TCP: too many orphaned sockets messages. My guess is this is sockets that are hanging around in TIME_WAIT after being closed that are waiting to be cleared up. I am interested…
andrew pate
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How long are fragmented TCP fragments kept in the TCP server

Suppose that a given TCP fragment is fragmented into two IP datagrams, and that the first datagram arrives to the TCP server, but the second datagram never arrives. After a certain amount of time the TCP server sends a keepalive, and determines that…
Randomblue
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Where are my TIME_WAITs on Mac OS X?

No TIME_WAITs on Mac OS X Normally, when a TCP connection is closed, the socket on the side where close() is called first is left in the TIME_WAIT state. When one of the peers is a Mac OS X (Lion) machine, no TIME_WAIT is listed by netstat -an on…
mgd
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Linux Slow Start: Changing ip route does not have any effect on initial window

I changed the tcp initial window in my machine to 10 as shown below [user@site etc]$ sudo ip route change default via 17.255.209.1 dev eth0 proto static initcwnd 10 And changed tcp_slow_start_after_idle as shown below [user@site etc]$ sudo…
Quintin Par
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socat: Show incoming connections

I am slightly going mad. Even if I call socat like this: socat -vvvv tcp4-listen:9000 tcp4-listen:9001 it works perfectly, but doesn't inform me about incoming TCP connections! Is there an additional verbosity option that makes socat show this…
Niklas B.
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Force forwarder DNS requests to TCP mode

I have set up a DNS-server on SLES10 (currently bind 9.6) on a multi-homed server. This server can be queried from all internal networks and delivers answers for all internal networks. We have two separate DNS "master" zones. Each of these zones is…
Nils
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Easy way to "edit" the traffic coming from a tcp host (linux)

I need to make some small modification to incoming traffic from a known tcp host:port before the process handling the connection get the stream. For example, let 192.168.1.88 be a remote host which runs a web server. I need that, when a process on…
etuardu
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