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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UDP causing problems with other connections

I have implemented a file transfer program on Windows 64-bit platform using winsock API. I am using a 1Gbps connection. When I transfer files using TCP protocol, I am getting only 320 Mbps. when I ...
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1answer
242 views

Session layer in OSI vs TCP/IP

I'm sort of confused here: According to several illustrations I've seen and material from Cisco the session layer from OSI is part of the application layer in TCP/IP. This makes no sense to me since ...
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2answers
65 views

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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1answer
216 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
277 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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2answers
73 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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2answers
213 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
1k 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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1answer
8k 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
89 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
11k 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
159 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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1answer
288 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
196 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
102 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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112 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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128 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
2k 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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543 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
452 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
995 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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166 views

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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233 views

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
162 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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5answers
10k views

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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1answer
51 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
34 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
471 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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771 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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0answers
547 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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2answers
13k views

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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2answers
275 views

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
138 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
1k 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
5k 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
3k 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
2k 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
604 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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468 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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40 views

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
915 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
318 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
471 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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2answers
460 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
131 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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1answer
66 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 ...
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1answer
137 views

Are all internet file downloads using FTP protocol?

I heard, FTP is used to transfer files over a network. Also heard that it uses TCP port 20 and 21. So TCP is connection oriented. We have acknowledgments. If the transmission is lost, we should be ...
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4answers
1k views

Can't host any server, ports blocked from external requests by accessible via LAN

I am running a Minecraft server hosted at TCP 25565 which I can access via LAN, but cannot be reached externally. I am not using any router and it is connected to an RG-Box Allied Telesis ...
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1answer
109 views

How can I fire many HTTP requests using a single TCP connection?

I would like to know if there is a way to open a single TCP connection to a server and request several pages over HTTP on that connection. Is there a way to do this using common Linux client tools?
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1answer
79 views

Why is it possible to continue working in a ssh session after a network disruption?

What enables the Secure Shell client and server to resume communication after one or several network interfaces in the communication path between them is shut down and re-appears some moments later? ...