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.

learn more… | top users | synonyms

3
votes
1answer
2k views

Is there a way to kill an open connection without killing the process?

I've search around and all the suggestions just say to kill the process. But I'm surprised I can't find any simple way to force a "connection" to close, without killing a pid associated with it. ...
1
vote
1answer
350 views

What does this tcpdump printout mean?

I'm not very experience with networking, so on my free time, I usually try and learn some more things about the internet and how it works. While at school, I came across tcpdump and wanted to give it ...
0
votes
1answer
1k views

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 ...
1
vote
0answers
171 views

Artificial network delay tcp/udp (bigger ping) for defined application? (windows)

I have a game where people can easy detect who i am looking at my ping, i want to make my ping highter. How can i set network delay for all network connections for defined application?
3
votes
2answers
2k views

Get the current/default value of TCP initcwnd on Linux

I can manipulate such value with: ip route change ... initcwnd 10 and then have a feedback with: ip route show But what about the default value before any modification? Is there a way to query ...
-2
votes
1answer
76 views

What happens if i send html over tcp without using the http protocol? [closed]

Will the html be delivered properly to the browser, or will it lack formatting? Will it get delivered at all?
1
vote
3answers
212 views

Is the following analogy to describe the relationship between TCP and HTTP correct?

TCP as a hose-pipe and HTTP as the water flowing through it I've just been reading some, and trying to conceptualize the difference between TCP and HTTP. I stole the analogy from here ...
0
votes
0answers
182 views

Windows 7 cannot connect to network shares, Exchange server, Webmail… anything requiring authentication

I have been handed this Asus Ultrabook that had Outlook 2010 that was not connecting to our Exchange server. It used to when in a different office. On our office network, it can't. I have 36 other ...
3
votes
2answers
225 views

Why does the IP address matter to IE9?

Start up Wireshark. Point IE9 to a local, nonroutable IP address. You will see a single TCP SYN packet try to connect to the host. Now point IE9 to a remote, routable IP address. You will see 2 ...
0
votes
2answers
950 views

Why can't a PC with 2 network cards be accessed by hostname?

I set up PC with 2 network cards, connected to the same LAN. I can connect to this PC (e.g. by remote desktop) only via IP addresses. Accessing by hostname does not work. Why is this the case? ...
0
votes
1answer
265 views

TCPview: Some strange process?

I just install the TCPview to check if there are any abnormalities in my computer connections, and there are something looks strange: There are 2-3 process that show the following status from time to ...
4
votes
2answers
867 views

How does the link speed affect TCP throughput? [closed]

Can someone explain to me how data is transmitted over a network using TCP/IP? Let's say I currently receive 500 Mbps of data over a 1 Gbps line right now. If I upgrade the line to 10 Gbps, would my ...
3
votes
1answer
166 views

Maximum TCP session time on Linux

I have two python scripts, which reside on different machines and are connected by a TCP connection. If the scripts do not share any data, they send dummy packets, so that the session is never idle ...
0
votes
1answer
470 views

TCP Connections/Session and Ports

I have some basic questions about ports and sessions. Since all these are related and simple questions, I've asked them together: I understand that for creating a connection we need a socket ...
0
votes
2answers
264 views

determine connections limit enforced by my ISP

I know my new ISP is enforcing a lot of different limitations. They refuse to say what are the limits. To determine bandwidth I can use sites like http://www.voiptest.org/ (BTW it shows me ~15% of ...
3
votes
2answers
4k views

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 ...
1
vote
0answers
164 views

Tunnelling TCP connection through NAT

My server is in my school's NAT and my desktop computer is in my home NAT. I want to SSH to my server from home. I normally used school's VPN, but recently for some reason I can't. So I'm looking for ...
1
vote
2answers
570 views

TCP/UDP hole punching from and to the same NAT network

I was wondering if tcp/udp hole punching would still work when you are in the same network (behind a NAT), and what the packet's path would be. What happens when using hole punching on the same ...
1
vote
1answer
66 views

Connection/pinging from/to WLAN

Sorry for the vague title, I'm finding it hard to describe the problem accurately in a few words (but that's probably because of me, English is not my native language). I'm trying to send a file from ...
2
votes
1answer
163 views

terminal tools and logs for debugging TCP issues

I have a server which I am testing for functionality (not load, not stress) with tsung. 50 users / second, 100 total users. Judging from tsung (tsung is the testing framework) graphs, there TCP ...
3
votes
0answers
187 views

Samba not connectable “Go away, we're not home”

I'm having an issue connecting to my dedicated server using samba. The server is a debian (squeeze) box running a samba server, only small modifications have been made to the default config and the ...
0
votes
1answer
4k views

Anonymous FTP: Please login with user and pass

I'm reading this RFC and just for exercise I am trying to connect to a FTP site. I'm trying to connect to ftp.freebsd.org via terminal. However as I've read in the RFC, an anonymous user is allowed to ...
0
votes
1answer
847 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 ...
6
votes
1answer
2k views

Why Windows 7 / PuTTY drop TCP connections even on very brief outages?

I have a small local network that piggybacks on a captive WiFi, and I use ssh on OS X with -oServerAliveInterval=240 and PuTTY 0.62 on Windows 7 Professional for establishing connections to my Linode, ...
88
votes
13answers
8k views

Must TCP use IP?

I have always heard that TCP is short for TCP/IP and they mean the same thing. However, is it not possible for TCP to be built on top of another protocol besides IP?
0
votes
1answer
217 views

How can I remap outgoing TCP ports?

Is there any way to remap a TCP port from a program were you not can change the port number? The program talks on port 4321 and I want it to go out on port 14321 on the local computer.
3
votes
1answer
188 views

How do I prevent connection resets upon pulling the ethernet cable?

In Windows, when you pull out (trip over it) a network cable, then the connections get reset. If you do the same on a Linux box or if you put a switch between PC and router and then pull the cable ...
2
votes
2answers
268 views

Program that blocks all TCP connections [closed]

Is there a program for Windows 7 that blocks all TCP connections, and ask for permission to use a new IP, then remembers? I cannot find anything like this and firewalls don't block every single IP .
0
votes
1answer
264 views

TCP-IP versus TCP-IP over VPN

What are the advantages and disadvantages of a TCP-IP connection over VPN opposed to a regular TCP-IP connection? I am interested mainly in speed and security! Thank you.
0
votes
1answer
110 views

What is the difference between :::: and 0.0.0.0 from the netstat -an output?

I just want to understand the difference between :::: and 0.0.0.0. I believe both are same which let connection from outside if any processor is listening to that port. udp 0 0 ...
8
votes
2answers
598 views

Puzzling TCP performance over 3G / UMTS

I'm using 3G as my primary internet connection, and TCP over this thing is getting more puzzling every day. For example: Downloading from kernel.org is crazy fast: $wget ...
2
votes
3answers
411 views

Are SSH protocol headers sent in the clear over a client-server connection?

I know routing information is always sent in the clear (oversimplification, but bear with me) so in a scenario where there exists an SSH tunnel between a client and a server using non-standard ports, ...
0
votes
0answers
112 views

Use of TCP-MD5 option

For a research application we need to use the TCP-MD5 option (RFC 2385). After some research we have finally found that only a few GNU/Linux distributions support the option out of the box. We ...
0
votes
2answers
204 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 ...
2
votes
2answers
6k views

How can i show only 127.0.0.1 traffic using Wireshark?

Every time I try to filter to just show a specific IP Address, I get an error indicating that it is "not an interface or a field." I have no idea what that means. Furthermore, I don’t really see ...
1
vote
1answer
279 views

Rule of thumb for TCP upstream bandwith requirement

In TCP, the recevier every now and then acknowledges the receipt of sent packages. Therefore to achieve a specific downstream bandwidth there is always a minimum upstream bandwidth required. What I'm ...
1
vote
1answer
8k views

Why did Microsoft change the TCP connection limit on Windows 8?

Looking through a Windows 8 installation I noticed that Microsoft changed the half open TCP collection limit to unlimited. It was previously argued that a limit helps stem the spread of malicious ...
0
votes
0answers
402 views

how can ftp to a hostname fail even though DNS provides the valide ip addr and ftp to the addr succeeds?

How is this possible? NodeX# ping ftp.company.com PING ftp.company.com (xx.yy.8.11) 56(84) bytes of data. 64 bytes from ftp.company.com (xx.yy.8.11): icmp_seq=1 ttl=127 time=0.657 ms ... ^C NodeX# ...
2
votes
0answers
56 views

Most network protocols occasionally fail

My Windows 7/64 machine has suddenly started to act funny. Everything will be running fine, when suddenly most network access methods will fail. These things continue to work: Accessing network ...
2
votes
4answers
2k views

Linux Command Line Tools for Analyzing OS + NIC TCP Latency

I'm hoping to find an existing Linux tool for measuring latency: I'm trying to diagnose how much latency my OS and NIC card are adding to TCP latency in Linux. I looked at the following tools but ...
0
votes
1answer
122 views

How to log selected tcp packet

I am troubleshooting a problem where a long TCP transaction (>=60s) would disconnect between my source (Point A) and destination (Point B), whilst passing through an internal Linux Gateway and several ...
1
vote
0answers
318 views

Create a VNC proxy with authentication

We have a bunch of VNC servers located on our local network. We wish to give external customers access to these VNC servers, via some sort of "middle-man" software solution which can handle ...
1
vote
1answer
379 views

Force DNS resolution to use TCP

My Comcast internet connection has been giving problems in DNS resolution, and I am guessing the reason is a probably broken or limited UDP. I am currently working around it by tunneling over TCP ...
4
votes
3answers
6k 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 ...
0
votes
1answer
97 views

Do TCP connections work differently within the same subnet?

I've encountered some network behaviour that confuses me while trying to get Java RMI working. I use netcat to connect to a local machine: [my_machine]$ nc -w 1 192.168.0.100 60000 && echo ...
2
votes
1answer
81 views

How does a server program distinguish between clients

Why does a web server listening on port 80 not get confused with many packets coming from different hosts. Why does it not confuse packets coming from the same host when different browsers access ...
1
vote
1answer
60 views

My sleeping process accepts TCP connections?

After sending the STOP signal to a process, it stops working as expected, but still accepts TCP connections. So is it working anyhow?
1
vote
1answer
187 views

TCP connection NOT lost? I've disconnected from the internet *exclamation mark*

This question arose from a dispute with a friend of mine. Over the last few weeks, I've encountered an odd phenomenon. All my connections are never torn down when I disconnect from the Internet. ...
1
vote
2answers
294 views

Download resume support blocked by isp?

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 ...
0
votes
2answers
129 views

Enabling access to a home server from “Internet” side

I wish to enable remote access to my linux home server, so I can use it when I'm not home. I tried doing so using port forwarding as follows: http://<RouterInternetIP>:<SomePort> => ...