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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TCP/IP minimal size

I am using a high level language on a PC to send a message via TCP/IP to a remote device which is an embedded device. I am sending relatively small messages (< 255 bytes). I must assume that there ...
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118 views

How to calculate TCP network speed

So basically this is an easy question, but not an easy answer. How do i calculate the download and upload speed in order to make program this in c#? I'm not sure how to take latency into account. I ...
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1answer
229 views

Why does writing IP addresses this alternate way work, and is there a practical use case for it? [duplicate]

Recently I saw an incorrectly typed telnet command, and I saw that "regular" numbers were interpreted to IP addresses. I tried this myself in Windows and the same behavior is shown there, so obviously ...
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67 views

Free official documentation for cables and models? [closed]

I've been looking through the ISO and IEEE sites for official documentation on the Open Systems Interconnection (OSI) model, TCP, and a range of cable standards (5/5e/6). However, other than on the ...
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161 views

Is DNS query a UDP or TCP?

I know that when we first type an address on the URL and enter. The DNS query starts. I don't who initiates, but my guess is application will only initiate the DNS query. The DNS query already knows ...
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2answers
745 views

how to find tcp streams without final ack/fin sequence in a huge packet capture file

I have a huge pcap file which contains a large number of individual tcp streams.But out of these , there are some invalid streams which dont have the final fin/ack sequence. Is there any way i can ...
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67 views

How do I drop a TCP packet matching a certain signature on windows (e.g. firewall-based)?

I am searching for a way to stop a TCP packet with a certain signature and connection from reaching an application. The packet may be dropped completely. The packet contains the byte signature [42, ...
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37 views

TCP windows scaling in Windows 7 works only alternate times

I am running iperf TCP client in loop from another program. I am getting high and low throughput alternate times. I also tried to use fresh installed Win 7. This behaviour is not seen in Win XP and ...
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1answer
5k views

Communication possible between 192.168.0.x and 192.168.1.x?

I have a problem I encounter on a regular basis. I have an access point with a fixed 192.168.0.x IP address. My network is 192.168.1.x. The problem is when I plug the access point into my network, it ...
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1answer
73 views

Throughput decreases after MTU 5000

I am trying to test throughput between two computers directly connected through 1 GbE and testing with iperf. I am getting a throughput around 980Mbps when MTU is between 5000 and 5050, however it ...
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2answers
9k views

How does circumventing IP restrictions through DNS work in the case of hulu.com?

I just heard from an australian guy that it is possible to watch hulu.com from Australia (which is actually restricted by country IP checks) by using certain DNS servers. Now I was wondering, how ...
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1answer
102 views

Why TCP performance degrade with bidirectional traffic?

I've made a simple experiment on TCP transportation performance. The experiment is as follows: There are two machines, A and B, each installed with Ubuntu 12.04 Server. I've installed "iperf" on ...
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200 views

Is it possible to create a WiFi TCP socket between two computers in a LAN?

Here is our setup. The FEZ Cobra II (WiFi) Single Board Computer with a RS9110-N-11-22-04 WiFi module and running the .NETMF 4.2 The documentation says that: This allows for real "Socket" ...
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2answers
119 views

Can using UDP and OpenVPN lead to file corruption?

I know with TCP that it always checks your files to ensure nothing got fragmented or lost or destroyed. So if I use UDP for OpenVPN to download files or access an internal network, does that mean I ...
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2answers
76 views

Capture packets from other machines in local network

Is it possible to capture packets from other local machines on my Mac? They are primarily all wireless as well, if that makes it any easier.
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78 views

Delete Hung TCP Sessions with SNMP

What I am trying to do, and failing horribly, is to close a TCP connection... I am trying to do this via SNMP and the functionality that is provided in the TCP MIB. First, I look at all the ...
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17 views

How to keep socket visible after closing the connection?

Is it possible to configure Linux to keep a tcp connection visible for netstat/lsof after being closed? (doesn't matter the connection state). I need to detect it with netstat/lsof but if the ...
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0answers
114 views

Windows 7 / PuTTY drop IPv6 TCP connections on brief outages

This is an IPv6-version of the following question: Why Windows 7 / PuTTY drop TCP connections even on very brief outages? After moving from IPv4 to IPv6, I've noticed that my IPv6 connections would ...
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1answer
1k views

What's up with port 8080 on my OSX box?

I thought a web server process I brought up was listening on localhost:8080, and tried to connect to it, but kept getting connection reset errors. As it turns out, I was mistaken and my process was ...
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380 views

how to kill a tcp connection in solaris operating system?

A client program connects to my server program written in JAVA via TCP connection (ServerSocket). I want to close the TCP connection between these two programs with a Solaris command or tool for ...
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1answer
365 views

Why is my tcp window size going to zero when using VIM over VPN

I use a mac os laptop over a typical (i.e. crappy) wireless home network and connect to work over a VPN. I ssh into the linux (ubuntu) desktop I have in my office at work. (When I say, "I ssh": I ...
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1answer
646 views

SYN-ACK not received

On a standard TCP connection between server and client, I have this issue: the SYN-ACK is not received from the client, while it is sent from the server. I could see this on Wireshark from both server ...
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18 views

TCP behavior in microsoft products

What happens when a TCP SYN segment is received on a closed port? Does windows send a RST or it just ignores it?
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No response received from github ssh randomly

My git pull started to stop working randomly with this error $ git pull ssh: connect to host github.com port 22: Connection timed out fatal: The remote end hung up unexpectedly I tried debugging ...
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TCP/IP resets (Linux, SSH, RDP, ADSL router)

I have an ADSL router (model Pirelli DR A226G) that seems to cause dropped tcp/ip connections (not ADSL connection per se). I have tracked it using Wireshark and captured a few cases and they always ...
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2answers
103 views

Does TCP verify data all at once or as a packet by packet verification?

I know that TCP uses verification to ensure accuracy of data by sending to the server. My question is does it verify everything at once or as it comes in? Quick Example: Let's say I am loading the ...
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260 views

What exactly TCPIP parameter StrictTimeWaitSeqCheck does?

From http://technet.microsoft.com/en-us/library/cc722796.aspx: This value indicates that a socket should not be reused before the time specified by TcpTimedWaitDelay passes. So, if it is 0, ...
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Ethernet vs TCP vs IP?

What is the difference between Ethernet, TCP, and IP in simple (simple abstract) terms? Please do not copy from Wikipedia...
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49 views

How to configure the physical machine and virtual machine?

If I want to transfer data between the physical machine (windows operating system) and virtual machine (Linux real time operating system). Could anyone please explain about configuring the data ...
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1answer
32 views

How does an ADSL modem tell which local client to associate with each response from a server?

Does an ADSL modem generate a random string for each request I make and when response comes it directs it to my computer (but not to my phone)?
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3answers
247 views

Is the same port acting as both client and server?

i find something strange in this netstat output. the output is taken using netstat -a -n -o -p TCP command on win 7. Proto Local Address Foreign Address State PID TCP ...
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28 views

Switching ethernet interfaces in Fedora

I am working on a computer which has two gigabit ethernet interfaces. This is the current configuration: PORT 1 (INTERNET) PORT 2 (SPP) Port 1 connects my computer to the internet whereas ...
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590 views

connect to a serial device via TCP socket

My setup is this: serial device ttyUSB0 connected to laptop A software that opens TCP socket to listen and write to, also runs on laptop A (linux) My goal is to pipe data from/to serial device ...
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500 views

MySQL crashes when connecting from localhost with tcp (UNIX sockets work)

I have Ubuntu 12.04 running MySQL server 5.5.24. I can connect with mysql --user root -p. status shows me : ... Connection: Localhost via UNIX socket ... When I try to connect with mysql --host ...
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what is type of ICMP packets? TCP or UDP

ping packets is a type of ICMP packets.Is there any relation between ICMP with TCP.In other can we guaranty their arrival in the network I want to know ICMP packets in the network is tcp or udp or ...
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Is there a way to pause/resume particular TCP connection?

I'm playing online game that matches me against random players. I found out that when I unplug my Ethernet cable, I have a minute to decide do I want this match to count. If things go wrong, I just ...
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1answer
114 views

How to monitor TCP and UDP port changes

I am running software on a server that may be turning off some ports and need to find out what it is. I have the ports I need to check. I just need to find out what is turning them off. How can I ...
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2answers
719 views

How to prove provider is blocking incoming traffic on some ports?

I hope this is not too much focused on home networks, because that's where I hit the problem, but I think it may be of general interest nonetheless. I have a cable connection (Cisco EPC3208) and a ...
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2answers
3k views

Why is my UDP so slow?

I'm using Iperf on two VMs and when using TCP I find the performance is as follows: notroot@ubuntu:~$ iperf -s ------------------------------------------------------------ Server listening on ...
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1answer
2k views

Redirect serial com to tcp port

I would like to know if exists some utility that connects to serial port and redirect input and output to a tcp port. I need this for a Java application, I need to write and read to a serial port but ...
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3answers
1k views

Can't connect to SSH server using WAN IP address [duplicate]

I have an SSH server behind a NAT router. Machines on the same (NAT'd) network as the SSH server can only connect to the SSH server using the LAN IP, not the WAN IP. Why? My network looks like this: ...
2
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1answer
422 views

Using tcpdump on displayed TCP data

If sudo tcpdump -i eth0 -X gives me tcpdump: verbose output suppressed, use -v or -vv for full protocol decode listening on eth0, link-type EN10MB (Ethernet), capture size 65535 bytes ...
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1answer
418 views

Ubuntu openVPN TCP no internet, UDP works. Win7 works on both TCP/UDP with same settings

I've recently purchased a VPN service which I'm connecting to with openVPN. On Windows 7 I can connect on both UDP and TCP settings, but when I'm trying the same thing on Ubuntu 13.04, it gives me ...
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I think that someone else is entering my computer for long, sth like back orifice. I then got TCPView. Now, what do I do?

I got some variations of the name of my own computer going on in TCPView, for instance. I wonder whether that means another computer, like in one instance the name appears in capital letters, in ...
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1answer
730 views

Connection stays alive but endpoint is dead?

Does anyone have an idea what would cause a TCP connection (client side) to stay in the ESTABLISHED state for about 24 hours, even though the server was restarted? The client process stays on the ...
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1answer
231 views

Using and testing UDP data over the internet [duplicate]

I have a GSM modem that sends data via UDP (it appears) I have configured it to send all data to my public IP address over the internet but no data is arriving at my end so I need to troubleshoot. I ...
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1answer
404 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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423 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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2answers
119 views

Does TCP care about the incoming port?

Does TCP care if the port changes on a SYN/ACK that comes back compared to the destination port asked for? I.E. If i have a port forward turning 80 into 8080, and the client sends a SYN on 80 and ...
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60 views

TCP freeze problems

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 ...