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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How much time does TCP waits before retransmission?

If I have a window size of 8 KB, then when 8 KB are sent to the other side and no ACK has been received, TCP will not send anything more until an ACK is received. But what if an ACK is not going to ...
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5answers
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Access Methods to a computer Using MAC Address

I have my own wifi network at home & recently when I checked the active clients on the wifi I found out the there is one active client. Router shows the MAC address of this client and I want to ...
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80 views

Not able to login to Tuleap after full installation due to TCP IP port configuration

Not able to login to Tuleap after full installation, as all the ports are in listen mode and 9091 port is not visible in ports.How to over come this and solve. With IP address we are getting tuleap ...
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113 views

Linux TCP buffer simulation

I would like to run simulations on the Linux TCP receive buffer to find out how big my buffer has to be. Is there any software available to perform such simulation? It would be handy to be able to ...
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1answer
144 views

Why does firefox send TCP packets even when idle?

I run firefox on Debian. I made a clean install with no cookies, or no information input from my side. I've also disabled all mumboo-jumboo healthy and crash report tracking. I've disabled 'shared ...
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3answers
856 views

How to manually send an ARP request

I recently sniffed with Tcpdump a packet "ARP, Request who-has 192.168.2.3 tell 192.168.2.2, length 28". I would like to reproduce this message, and to send an ARP request from my laptop to any IP I ...
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220 views

Tcp connection target machine actively refused

I have a simple TCP client/server program on two laptops. The server should work fine as I use "netstat -anb" and the server shows up as listening, "0.0.0.0:102", then my client connection failed, ...
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411 views

Which congestion control algorithm is used by the TCP stack in OS X?

What congestion control algorithm is implemented in TCP in OSX 10.9? I would like to know if it uses NewReno, or something newer like Cubic in Linux.
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196 views

TCP socket to serial port

Is is possibile to remotely access a serial port by tcp socket server? Exists this kind of software? It is the opposit of this question: Any free application to redirect serial communication to TCP/IP?...
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15answers
76k views

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 ...
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1answer
57 views

Decrypt SSL at the TCP level

I'm trying to decrypt SSL at the TCP level for data that I'm sending to a remote server. The reason I'm doing this is because the remote host intermittently sends me RSTs, and I'm trying to identify a ...
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47 views

TCP socket communication from client to server

I am trying to test the performance of a client/server application that uses TCP communication. If I trigger multiple requests from the client, would it flow through the same connection/pipe to the ...
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Route only on output chain?

I have two machines A and B. I want to send iperf traffic from A to B, but first have it route through a userspace program on A. I did this with a tunneling device: therefore, I used the command ip ...
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3answers
4k views

How to monitor TCP connections over time

I have an application which is a windows service. It accesses a number of other services using TCP/IP. E.g. sql server databases, informix databases, mail servers, etc. For instance it will also ...
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2answers
1k views

Data retransmission and WSAECONNABORTED (10053) socket error

Say I have two sockets that are connected to each other (Socket A and Socket B). If the computer that have Socket B is unplugged from power, then if Socket A tries to send some data to Socket B, the ...
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1answer
284 views

ISP Issues - TCP Out-of-Order

Accessing any webpage (basically any TCP connection), results in multiple retries before and long loading times before it loads a page with missing elements (reload might fix it). Google Chrome throws ...
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2answers
166 views

Are FIN packets guaranteed to arrive?

In the 4-way handshake, we have the following: FIN -------> <------- ACK <---x--- FIN (what if this packet is lost?) ACK -------> What happens if the third packet is lost, will it be re-...
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72 views

Monitor TCP port traffic and get a sound alert when a specific text string is found on Windows

I need to watch a port for several hours and make an audible alert whenever a specific string comes through. Windows only. Is this possible with Wireshark or another sniffer tool or maybe a sniffer ...
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1answer
171 views

Bittorrent client makes multiple connections upon its start to amazonaws

I have this weird situation that every time I open my bittorrent client application, upon its start, it starts to make a lot of multiple connections(more than thousands) to amazonaws servers and as ...
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1answer
159 views

How to share via TCP serial port CAT

I want to connect my amateur radio transceiver to a linux (Ubuntu) computer with USB cable (serial port (in windows should be COM3 or COM4) like /dev/??? ) and share it locally with TCP, Is it ...
32
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1answer
4k views

What happens to TCP connections when I remove the ethernet cable?

For a TCP connection, when I remove the cable and reconnect after 30-40 seconds there is no packet loss issues. But when the reconnect time is more than a few minutes all the packets are lost. I know ...
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5answers
904 views

What ports are used by an application [duplicate]

I'm testing an application which opens its own ports (acts as a server for these ports, hence listens at that ports) and where the same application connects to ports bound by other applications (acts ...
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1answer
591 views

Man in the middle using iptables

I wish to test a subsystems which communicates with another subsystems via tcp. I have used the following: "iptables -A OUTPUT -p tcp --dport "+port_number" -j DROP" to stop the traffic on a port ...
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2answers
777 views

If HTTP runs on a port, does that mean TCP can also run on that port?

I'm building an app that needs to run on a mobile smartphone over a GPRS/3G network. I'm doing bit ops, so every byte wasted through HTTP headers is bad. Mobile providers in my area make heavy use of ...
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279 views

What is the primary function of the transport layer in the Internet protocol networking code [closed]

I am not sure if I have answered this question right, so would appreciate it if someone could correct me. The question is: What is the primary function of the transport layer in the Internet protocol ...
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329 views

VMware TCP port mapping not working - port not accessible via public IP address

Simply speaking, the forwarded port 45922 is accessible on the host via 127.0.0.1:45922, but not accessible on the host itself via its public IP plus port number 45922. Details are as follows. Host ...
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1answer
184 views

List all open sockets in /dev/tcp/localhost/

Is it possible to list all open sockets in /dev/tcp/localhost/ on a Linux machine? I want to list all sockets where the following command would return 0: timeout 2 bash -c "cat < /dev/null > /...
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1answer
853 views

TCP congestion control Windows 7

Based on what I read, Compound TCP is disabled by default in Windows 7. If so, which default congestion control algorithm does windows 7 use? Is it TCP RENO or NEW RENO? Could you give me some links ...
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1answer
153 views

Wget not getting cookies, not pulling back results in check.

I'm having a couple of issues when porting check scripts between a couple of servers. The script. #!/bin/bash hostname=$1 port=$2 retstatus=0 retStr= st=`date "+%s.%N"` if [ $# -ne 2 ]; then ...
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2answers
146 views

How are Internet connections differentiated from each other by an operating system?

Given this example, how would my operating system differentiate between each request. Let us say I have 3 tabs open, and at the same exact time, they all go to http://google.com. How would my ...
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78 views

How can one redirect to a new host all traffic destined for an old host?

We're moving a bunch of services, say from 1.2.3.4 to 5.6.7.8. In order to test that the new services are correctly configured, we'd like to redirect (to the new host) all traffic destined for the ...
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1answer
751 views

RPC Connection Filtered with no Firewalls

I have a workstation (PC1) that cannot communicate with a domain controller over RPC (TCP/135). C:\PortQryV2> portqry.exe -n 192.168.1.1 -p tcp -o 135 Querying target system called: 192.168.1.1 ...
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TCP Dup ACK/Retransmission, bad configuration?

I'm currently investigating network issues of a friends LAN (again). The Internet connectivity is very slow and unreliable and sometimes services simply don't work. I've monitored the traffic for ...
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191 views

iptables TCP flags

I'm beginner with iptables and networking so please excuse me for such beginner questions. I found on the Internet part of filtering malformed packets: /usr/bin/sudo /sbin/iptables -A tcpchk -p tcp -...
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6 views

What happens when I terminate a process and the socket send buffer is not empty? [duplicate]

In Windows (and probably in other operating systems), if a process has a TCP connection with another process on another machine, and then I terminate the process, an RST packet will be sent to the ...
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1answer
191 views

What happens when I terminate a process and the socket send buffer is not empty?

In Windows (and probably in other operating systems), if a process has a TCP connection with another process on another machine, and then I terminate the process, an RST packet will be sent to the ...
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1answer
54 views

3 duplicate ACKs in TCP

If a client receives 3 duplicate ACKs in TCP then it will half the window size and switch from slow start to congestion avoidance. Will it retransmit the next window_size segments, or will it just ...
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1answer
49 views

Multiple TCP Connections to download simple webpage and images?

I created a very simple webpage: <html> <body> foo bar <img src="img1.png"/> <img src="img2.png"/> <img src="img3.png"/> Hello world </body> </html> And ...
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2answers
696 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 ...
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9answers
3k views

How to make Firefox use TCP for DNS

I want to use TCP for DNS, to bypass my ISP's slow and broken DNS servers. I'm not using (and don't want to use) a proxy. Note: I want to use DNS over TCP because if I use it over udp, no matter what ...
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1answer
412 views

How to redirect TCP traffic from one virtual machine to another in Linux?

What is the simplest way to redirect all TCP traffic from one virtual machine to another in Ubuntu Linux and reverse? And what type of connection I suppose to use in VirtualBox?
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1answer
282 views

HTTP performance over high latency links

I have users that previously used FTP for file transfers across high latency paths to their local server. They have switched to HTTP for these transfers (not by choice) and file transfer perforamance ...
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222 views

Tunneling trough VPN over TCP

I'm currently trying to set up a VPN on my server to connect to from my Laptop. The server is a command-line ubuntu running on a x64 machine. The Laptop runs x64 Windows 7. The VPN itself is already ...
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1answer
93 views

How do you force linux to treat a tcp packet as if it were at the destination ip?

The situation: A tcp packet arrives on eth0 with destination 8.8.8.8. This packet meets some criteria that makes me want to intercept it (lets say I am interested in all packets from source 10.0.0....
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1answer
81 views

Forward TCP packets by destination and port number

Is there any way to forward only TCP packets heading to destination XYZ and port number NN to 127.0.0.1 port number 9150 ? I'm on Windows. Thanks
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1answer
46 views

Receive encrypted string from server [closed]

What is the easiest way (as easy as possible) to make a web server that will check a string received from client and respond with another string? How to do it from the very beginning to the very end? (...
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188 views

How to split pcap files maintaining tcp sessions

I have a pcap file which contains tcp traces. I was wondering if there's a way to split these traces in order to maintain tcp flows, but also filtering the traffic on a src ip basis. For example, if ...
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0answers
122 views

Force local packet pass trough the router (or disable loopback) - windows 8

i would like to avoid that packets sent from my machine to the same machine (via the IP assigned by the external router eg. 192.168.1.20) are routed with loopback and so never reach the external ...
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1answer
383 views

What is the timeframe used, for TCPBacklogDrop value calculation in netstat [closed]

I'm interested in the value TCPBacklogDrop of the command netstat -s on linux. But I don't know which timeframe is considered, when calculating it.