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 can I tunnel all traffic including UDP connections through a http proxy [on hold]

Hello members I want to either block all UDP or be able to tunnel it through TCP connections. Whatever i tried the DNS resolver simply don't obeys the rule and always uses the UDP. Tried blocking but ...
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1answer
59 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
34 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 ...
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26 views

Should I disable Netbios over TCP/IP for printing throught Samba+cups?

I have a domain with 100+ machine which are reparted on two IP ranges. On this moment, computers are using netBIOS over TCP/IP or SMB over TCP/IP. It seem that two requests are send ...
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1answer
3k 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
730 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
26 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
100 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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5answers
12k views

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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0answers
24 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
57 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
34 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
71 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
34 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
51 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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0answers
32 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
114 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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2answers
160 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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0answers
61 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
39 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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13answers
56k 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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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
91 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
15 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
23 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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24 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
38 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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2answers
536 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
2k 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
82 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
28 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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2answers
12k views

For what does ssh use UDP?

Wile doing research I noticed that SSH both uses TCP and UDP. I completely understand the use of TCP, but UDP seems a bit strange. Why would I use an "unreliable" transport protocol with minimal ...
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44 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
31 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
23 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
45 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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0answers
58 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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0answers
136 views

netsh set autotuninglevel: “the parameter is incorrect”

When trying to do netsh int tcp set global autotuninglevel=disabled from a command prompt, I get the error message "The parameter is incorrect". Several search results suggested "disabling 64-bit ...
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74 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
51 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 ...
0
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1answer
102 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.
3
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1answer
367 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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3answers
83 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 ...
26
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4answers
57k views

What does “On-link” mean on the result of “route print” command?

I'm using Windows 7. When I type "route print" under command prompt, I get a IPv4 Route Table with several "On-link" values under the Gateway column. For example, like this one: IPv4 Route Table ...
0
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1answer
105 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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1answer
78 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 ...
25
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3answers
10k views

How does Router know where to forward packet

If several computers with local addresses (192.168.0.#) are connected to a router and each computer opens a web browser and requests a page over HTTP, when these TCP:80 packets are sent out, the ...
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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: ...
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1answer
66 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 ...