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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Can't access HTTP server, but ping works in LAN

I encounter a problem when configure the connection. My computer resides in a LAN, I want to assign it a static IP address. Thus with the help of port mapping on the router, I will be able to access ...
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5k views

How does Ident work?

I am having a hard time understanding how the ident protocol works. I came across a summary of how it works at Wikipedia however don't quite follow what it means The Ident Protocol is designed to ...
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548 views

Why small TCP connections succeeds, but big ones fails?

Sometimes from Linux system I see the following weird behaviour: I able to ping things and sometimes use some services, but networking is very bad. For example, now I routed connection through my ...
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How to change TCP “time wait” delay in Windows 7 / 2008 Server?

Windows Server 2003 "offers two methods of controlling TIME-WAIT behavior." The TcpTimedWaitDelay registry value under the HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters ...
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How do I redirect a request for an IP to the loopback?

A program I'm using makes a request for the external IP 74.125.234.83 and I would like to make this request redirect to 127.0.0.1 so I can test my local server, I don't have access to the source of ...
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How does a router route connections?

How does a router track connections? When you send a http request it goes to the router which is then sent to another router, etc over the internet; but then how does it know to go to the server, is ...
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974 views

Ubuntu Server static Route through ubuntu PC

Working my way through understanding Linux. I still consider myself a newbie. I recently installed a 10.04 server with LAMP and others on it. I wish to get it surfing the net: apt-get update and ...
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iodine fails its ping test

I'm trying to get iodine working on my Ubuntu machine. The server is working fine, but when it try to establish a connection, and change the route table using the default iodine-client-start script i ...
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913 views

Understanding port forwarding and NAT

I've got some confusion about port forwarding vs NAT. I know the problems NAT causes for P2P, and that there exist some solutions to it (STUN,TURN,etc) which require a relay server to setup direct ...
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How to make tcpdump (or other tool) to actually dump TCP stream?

I expect something like this: $ nc example.com 80 GET / HTTP/1.0 HTTP/1.0 500 K.O. Content-Type: application/null Content-Length: -1 $ Meanwhile: # tcpdump -i eth0 --actually-dump-all-tcp ...
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Distinct Proxying for any TCP-related Protocol

I'm not sure what to call it (proxy/redirection/relay), and I am hoping some software or solution possibly exists for linux. My intention is to be able to listen on a single public facing ip:port ...
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TCP Slow start and congestion control, and how to modify them

I'm trying to change the behavior of the tcp slow start protocol on a CentOS5 box (uname -r => 2.6.18-238.12.1.el5). I have read that the following command will change my icwnd to 8: ip route change ...
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426 views

How can I open a TCP/UDP connection on Linux?

I am looking for a simple command line tool to open TCP/UDP server/client on a desired port on a Linux machine. Are there any applications or commands that I can use to achieve this?
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266 views

tcptraceroute showing paths of greatly varying length

I'm tracing a path to my server using tcptraceroute. The server is showing intermittent network availability. It's as if some packets get through fine, others take a long time and some never get ...
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101 views

TCP connection between PCs in home wi-fi network

I want to establish a connection between 2 PCs. Point is to practice in writing client-server applications and similar stuff. I've heard around, that I can access another PC in network by address like ...
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2answers
926 views

How to increase transfer speed on fat long pipe?

I have a log pipe between two facilities (gigiabit circuit with RTT latency of 17ms). When doing system-to-system file transfer (file sharing, rsync, ftp, sftp) I'm hitting maximum speed of approx 30 ...
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4answers
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what is TCP Half Open Connection and TCP half closed connection

I am trying to understand what is the difference between TCP Half Open Connection and TCP Half closed connection can any one tell what exactly are they?
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984 views

why does my time warner cable modem connection enter dead period states every 20 mins?

My wifi connection (from my MacBook running Snow Leopard) to a Time Warrner cabel model and router has a recurring connection problem. Every 20 minutes or so it will enter a "dead state" where no ...
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How to use DNS over TCP?

Google DNS (8.8.8.8 and 8.8.4.4) are blocked (or polluted) by all ISPs available to me (and DNS by ISPs just return wrong answers for some sensitive sites!!), and it is said that if we change DNS from ...
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3answers
9k views

Cannot connect to guest OS from host OS

I have installed OpenSUSE on VMWare player as guest OS and my host OS is Windows XP. What I want to achieve is to send message from my host (i.e XP), say on port 7000 and receive it on a specific port ...
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90 views

Mysterious packet loss

Sender station: Receiver station: The two computers are directly connected one to another without any switch or router. Netstat gives no clue what is happening. Amount of received packets is ...
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400 views

Network being flooded with TCP Junk

I've been using Wireshark to check out the traffic on my home network. Fairly recently, I started getting a bunch of junk generated constantly. I've been unable to find out the cause, as virus/spyware ...
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228 views

is there a single-end available bandwidth measurement tool

i am doing my graduation thesis,currently i need a tool that is capable of measuring the available bandwidth between client and servers.i have googled that, the link ...
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iptables for transparent TCP proxy

Here's my situation. I have an iPad, a TiVo, and an dd-wrt router on my network, along with a machine that I'd like to use to sniff/decrypt draffic between the iPad and the TiVo. The iPad has an app ...
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TCP Retransmission vs. TCP Fast Retransmission

In Wireshark I can see things that say "TCP Retransmission" and "TCP Fast Retransmission." What's the difference? How is Wireshark able to tell the difference?
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573 views

Server response in TCP 3-way handshake

A server normally responds with SYN ACK in a 3-way handshake. What would happen if it just responded with ACK?
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How to manually do a TCP handshake

Telnet can be used to manually do things that programs do automatically. When I connect to a server I noticed that it automatically does the 3-way handshake to establish a TCP connection. Can it be ...
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How to connect to `tcp://192.168.202.112:11053` by command line?

tcp://192.168.202.112:11053 I've ensured the service is on,but when telnet 192.168.202.112 11053,connection fails,why?
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538 views

Any free program for binary TCP communication?

I have a TCP server listening on a localhost's port so I need a software that can be used to establish a TCP connection to the server and then send binary data, not ASCII. For example, I want to send ...
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How exactly does a proxy work?

If I want to connect to say, IP 100.100.100.100, Port 80, my computer will send a tcp packet with this adress into the wire. Now If I use a proxy server say, 200.200.200.200 Port 8080 (such kind of ...
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Count exchanged bytes per TCP connection

I need to get a table updated with the exchanged bytes (Rx and/or Tx) for each ESTABLISHED TCP connection on a linux machine (well, at least, a list of connections (port ranges), thus not actually ...
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Why is multi thread downloading faster than single thread?

There is one large file in my server. I find that multi thread download can get 20Mbs, but single thread can get 10Mbps, can anyone explain this?
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How to set TCP/IP abort interval or timeout in Windows XP?

Does anyone know how to set the TCP/IP abort interval or timeout in Windows XP? In my machine, when I open http://129.129.129.129 in IE, Firefox, or Google Chrome, it will cost about 20 seconds to ...
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How do networking ports work? Can I configure the ports that client and server use?

Let's say i have a "server" program listening on address 1.2.3.4:69 (i.e. remote port 69) When i connect from a "client" program to it, typically i would specify the IP address + port of the target ...
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closing open TCP ports under WinXP SP3

I must confess I have not been very security-conscious over the last few years, and I just did an NMAP scan of my computer to see how it was doing. The results amazed me. There were literally ...
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tcpview cannot kill connection/process

I have a program that sometime misses to close a tcp connection. After the program has ended I can see that the port is taken. TCPViewer shows "non-existent" in the "Process" column. If i try to ...
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Inbound TCP connection limit in Windows 7

I've done a bit of searching on the internet trying to find out whether there is an INBOUND TCP connection limit on Windows 7. We're writing a server product which processes data from a number of ...
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Is there a hard limit of 65536 open TCP connections per IP address on linux?

Is there a hard limit of 65536 open TCP connections per IP address on linux? I read somewhere that there was, but someone is asking for confirmation and i just can't find it. I seem to remember it ...
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tcpdump missing on Cygwin v1.7.7 for packet sniffing

I am trying to debug why my TCP packets are truncated. I see that only the first 24 bytes of each packet are showing up in my program. The 25th through 28th bytes are scrambled and all others after ...
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Software using Socket Based TCP connection cannot connect to server

On my computer other network based software are able to connect to servers and I am able to surf the internet as well on this computer however there is a software that uses socket based tcp connection ...
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Size of an IP Packet

What is the complete size of an IP Packet?
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What's the minimum size of a TCP packet

A post here: http://blogs.adobe.com/dreamweaver/2011/02/optimal-css-tiled-background-image-size.html staes that "The smallest download that browsers can do is 1K bytes." Is this due to minimum size ...
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Comparison: UDP vs TCP [closed]

UDP vs TCP. What are these ? What are their Differences, pros and cons ?
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What does netstat mean by “acknowledgments not containing data received”?

Netstat reports some TCP packets in the following category acknowledgments not containing data received. However, I'm not clear what this phrase means. Goggling and the netstat documentation don't ...
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54 views

Which element of network refused connection

How could I determine, which element of the network actually refused/closed the connection?
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437 views

Add new port forwarding entry (TCP) on iMac

I'm on an iMac, Leopard OSX, and I need to add a new port forwarding entry (TCP protocol) in the iMac itself, since I have no router/modem connected to the iMac, I have Fiber, a network cable from the ...
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822 views

Finding all processes that are using a given port [duplicate]

Possible Duplicate: Finding the process that is using a certain port in Linux More specifically, how can I find out what processes are using port 8080 (for example a web server)?
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109 views

ICMP protocol place in network layers

I would like to ask you question about Internet Protocol. On Wikipedia, they have ICMP protocol on the same level of network architecture as IP protocol, but that is wrong, right? ICMP should be on ...
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HP G61 Notebook: TCP seems to be dead

Can't say I'm much of a Windows expert, but this is somewhat of a weird occurence. I'm in front of a HP G61 Notebook laptop with Win7 that has connectivity problems. I mean that it's connected to the ...
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How do I kill a process that is dead but listening?

I'm developing an app that listens on port 3000. Apparently there's an instance of it still listening to the port because whenever I start it, it can't create a listener (C#, TcpListener, but that's ...