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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Linux Command to set TCP window size [closed]

I want to send TCP packet with window size 65535 (0xffff). I m looking to set the TCP window size to 65535 on my linux system. I know that there is the sysctl command but I could not find how ...
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15 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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1answer
19 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
30 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
28 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
22 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
49 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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27 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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31 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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2answers
84 views

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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28 views

iptables TCP flags

I'm beginner with iptables and networking so please excuse me for such dump questions. I found in Internet part of filtering malformed packets: /usr/bin/sudo /sbin/iptables -A tcpchk -p tcp ...
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0answers
41 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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0answers
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
79 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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0answers
13 views

Determining whether a port is closed (no one is listening) or iptables reject my host

Can I tell whether the service I'm calling has a reject rule in its iptables or it doesn't listen on the port I'm calling? it seems that I always get icmp port unreachable
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1answer
22 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
22 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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0answers
20 views

Check if ports are open for talking

I have a software (HP BSM) installed in a Windows server 2008 R2 Std This software needs to "talk" through a specific list of TCP ports and "listen" through other TCP ports. How can I know/check if ...
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1answer
29 views

Why is the FIN flag in TCP called FIN?

There are some flags in TCP. I already understand what other flag names come from, such as SYN stands for synchronization. I also know that FIN is used to close a connection. What I don't understand ...
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1answer
26 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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1answer
58 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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36 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
22 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 ...
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1answer
18 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
64 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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1answer
44 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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37 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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42 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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60 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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3answers
79 views

What happens when 2 hosts simultaneous establish a connection in a 3-way handshake

Say two hosts, A and B, both attempt to start a connection with each other, but the SYN from A gets to B before B's SYN arrives at A. My answer is that A would sent SYN ACK and would ignore the SYN ...
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1answer
288 views

Localhost tcp throughput performance differences

I have been using psping for measuring bandwith statistics on localhost on different computers: laptops, home computers and servers. All of them get to between 100 and 200 MB/s but my PowerPc at work ...
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1answer
78 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.
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1answer
70 views

Changing TCP sliding window behaviour

We all know that TCP's congestion control uses additive (linear) increase and multiplicative decrease when adjusting sliding window size. Is there a way to change it to "linear decrease"? When a ...
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1answer
83 views

Testing DNS truncated queries over TCP with dig

I want to test if my network supports EDNS0. It means that if the record is bigger than 512byte, the DNS will be over TCP. It will ne truncated at firts using UDP ,the it willbe over tcp. I'm using ...
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61 views

Cannot open port 25565 and others

I try to open my Minecraft server and my gmod server ports. Now I only try Minecraft and I tried to open in 192.168.1.1 in Windows firewall. I went to this site: ...
2
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1answer
55 views

Sending large data over TCP and progress indicators

It is my understanding that when you open a tcp connection to send data the tcp layer on the receiving end holds on to all the packet until the transmission is complete, then sends all the data up to ...
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94 views

Windows 7 stops responding to my SYN requests unless I continue to ping the client

Basic synopsis, my Windows 7 box stops sending RST, ACK packets to a client which is sending SYN packets after time. What I know: I have a client who sends a SYN packet, followed by a retransmit 3 ...
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1answer
39 views

Can I ping a host that has disabled the ICMP Ping option?

I need to know if it's possible to compare and test how fast is an IP (ie: any web or game server) relative to my location (in terms of network latency), even if they have disabled ICMP/Ping requests ...
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1answer
52 views

Different servers on the same port ipv4 / ipv6

Say I have two TCP servers A and B. A is an ipv4-only server listening on 127.0.0.1:10000. B is an ipv6-only server listening on ::1:10000. Can I start these on the same machine? That is, how are IP ...
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142 views

Retransmitted TCP packets (smaller than original) are being dropped, causes hang

I'm trying to troubleshoot my home internet connection, which often hangs on large downloads. I believe I have been able to duplicate the problem between my home computer and an Amazon EC2 instance ...
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1answer
62 views

TCP server listen and client listen windows software

I am using Windows OS on an amazon cloud AWS with static public IP. On this machine I need to set up a TCP server to listen on port 2204 for raw data that will arrive from a GPS base station over TCP ...
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1answer
131 views

Forcing a game to not take “real local IP” into account but only recognize virtual local IP assigned by VPN server

We are two friends who want to play Heroes of Might and Magic 2, 3 or 5 together in online multiplayer mode over internet using a TCP/IP connection. As we are not happy with third party solutions ...
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5answers
2k views

How does a server get notified about the HTTP request?

I have a basic understanding of how HTTP works. I understand the client (web browser) makes a request and server responds back to the request. However, the thing I don't understand is how does a web ...
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0answers
26 views

Window Period Where Sent Packets Cause Socket Acting as Server to Malfunction

I am currently working on an embedded Linux server. My main application is a state-machine that is started during the init phase from the rc-scripts. The application spawns several worker threads. ...
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3answers
156 views

How does a web server return an HTTP request?

I'm sorry if this is a really stupid question; my networking knowledge is pretty sparse. So, a user makes a HTTP request to some address. That request comes from an address on a local subnet, but the ...
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0answers
21 views

Assessing Performance in Process Explorer: Varying Block Sizes

I am trying to assess the performance of my scientific software using Process Explorer, with the files both locally on our blade server (Dell VRTx, Windows Server 2012) and over the network from ...
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1answer
106 views

Accessing two devices with the same IP?

I want to connect my laptop to two WiFi enabled digital cameras, that have the same IP hardcoded: 192.168.1.1 One solution that I've successfully tried: Connect one device to the laptop's built in ...
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1answer
278 views

Cannot connect to 192.168.1.1

I have router TP Link n900 and I cannot connect to my admin panel of the router, I just bought it, I have internet when I am connected with cabel, but cannot open the router. My connection is : PC -> ...
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4answers
4k views

How does HTTP become stateless?

HTTP is said to be stateless. Meaning, it doesn’t need to store information for the transmission of data. But HTTP uses TCP, which is state oriented. If that's the case, how does HTTP becomes ...
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32 views

Network tcp parameters

i have a netstat -s output which i would like some opinions on. Which are the parameters that seems to appear to have problems? from what I can see, tcpInUnorderBytes and tcpInUnorderSegs have some ...