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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During queuing delay, do TCP, IP, and Data Link headers act as a packet or 3 different packets?

According to the definition from wikipedia, I found processing delay to be the delay caused by router processing the packet header. I am just wondering are TCP, IP, and Data link Headers all ...
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Still Lost on Blocking TCP Port Connections form Terminal

I'm still not 100% understanding what to do in Terminal to block certain URLs for specific ports. And I don't want to use Little Snitch. I really want to wrap my head around this. So if someone can ...
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2answers
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what distinguished OSI from TCP/IP in practice?

so i am going through cisco ccent/ccna. working through the text on my own just for general useful knowledge. so in the early part of the book it goes into describing the different layers of the TCP/...
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1answer
21 views

Where do I start to troubleshoot this strange activity from my firewall?

I noticed that my firewall yesterday blocked outgoing attempts starting at port 61494 and worked its way up to 62381, making a TCP outgoing attempt at each port once. The remote IP address seems ...
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24 views

TCP and UDP do not work with firewall

I can not connect my TCP-Client to my TCP-Server. Here is my Code: http://stackoverflow.com/questions/35661591/tcp-server-does-not-work-with-firewall I have already opened my TCP-Port "8888" in the ...
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Why ICMP is different that TCP and UDP? [closed]

what is the difference between Internet Control Messaging Protocol over Transmission Control Protocol and User Datagram Protocol
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1answer
1k views

How can I setup a Bluetooth device to serve web pages to a BT client via TCP/HTTP?

I'm thinking of making a linux-based Blueooth enabled device, which allows an external client (e.g. a laptop) to connect to it via TCP over Bluetooth and retrive web pages which allow it to interact ...
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3answers
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Get the current/default value of TCP initcwnd on Linux

I can manipulate such value with: ip route change ... initcwnd 10 and then have a feedback with: ip route show But what about the default value before any modification? Is there a way to query ...
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1answer
53 views

Can HTTP deliver video over the internet or is that TCP?

The post below talks about delivering video content to users via HTTP. Is it confusing it with the TCP protocol? https://torrentfreak.com/torrents-time-brings-popcorn-time-to-any-windows-browser-...
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63 views

How to simulate TCP simultaneous open and close conditions?

I am learning TCP/IP protocol. I want to see simultaneous open, close, half open/close, etc conditions in practice. I have created simple TCP server and client program. How can I simulate simultaneous ...
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what is TCP Half Open Connection and TCP half closed connection

I am trying to understand what is the difference between TCP Half Open Connection and TCP Half closed connection can any one tell what exactly are they?
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1answer
903 views

Is ICMP port unreachable error generated by both TCP and UDP? [closed]

A program on machine X attempts to open a UDP connection to port 5376 on a machine Y, and a TCP connection to port 8632 on machine Z. However, there are no applications listening at the corresponding ...
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Is there a way to completely disable TCP keepalive?

I'm trying to disable TCP Keepalive in a linux machine. If I set the three keepalive parameters to 0, the machine refuses connections. sysctl net.ipv4.tcp_keepalive_time=0 sysctl net.ipv4....
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Ubuntu IPTables

I started hosting my game-server on Ubuntu Linux 14.04 I am having an issues ، some enemies/bug abusers log in 2+ characters in the same second then they spam a certain spell/word that lags/stops my ...
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23 views

How to know that I passed the firewall from the TCP connections?

In my company, in order to access some intranet-sites, I have first to login to webpage (which I suppose is a firewall or something) with my account. If I login from FF for example, I can access the ...
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56 views

NAT doesn't allow TCP ACK for sent TCP SYN

We are using TCP Simultaneous Open for connecting TCP socket. Lets call one SideA and other SideB. From the wireshark log I see that first two SYN sent from SideB is blocked by SideA NAT. Then SideA ...
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1answer
589 views

make Xvfb listen only on local ip

to use graphical software even on my debian based systems without graphic cards (or in addition to its main graphic) i use the virtual frame buffer x server Xvfb. I am starting it with a little bash ...
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2answers
303 views

DNS Resolver for Windows over TCP

I know that DNS uses UDP with Port 53 for DNS queries. However, at my place sometimes UDP requests are blocked and DNS fails. I know that there is protocol for DNS over TCP and many public DNS servers ...
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2answers
45 views

How does a Router/Modem obtain the Port Number from an IP Datagram?

The IP datagram header is a layer below the TCP segment which contains information on the port. Therefore before a firewall can inspect a port number, must the IP datagrams be rebuilt into the TCP ...
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25 views

Wireshark FTP multiple ACK?

I'm trying to visualise somes frames that correspond to a file transfer between two machines on Wireshark. The thing is that there are multiple ACK for each FTP-DATA segment and I don't understand ...
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74 views

Replay captured TCP packets

I captured a tcp traffic using wireshark and saved the traffic in pcap file. I did two tests: Test 1: sudo tcprewrite --infile=capturedtraffic.pcap --outfile=temp.pcap --srcipmap=0.0.0.0/0:192....
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0answers
635 views

iodine fails its ping test

I'm trying to get iodine working on my Ubuntu machine. The server is working fine, but when it try to establish a connection, and change the route table using the default iodine-client-start script i ...
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1answer
100 views

Connection remains flagged as ESTABLISHED even if host is unconnected

I am working on a Linux embedded distribution and I need to monitor incoming and outcoming connections (if they are still actives etc.) and I am experiencing issues because I noticed that, even if the ...
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1answer
52 views

Windows 7 pc opening port 139 from random IP addresses

When I run CurrPorts (a TCP monitoring tool for nirsoft) I get the expected output plus entries that I do not understand. My LAN is 192.168.1.x. My pc is set to a static IP of 192.168.1.12. But I find ...
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1answer
41 views

Ways in Which TCP/IP Stack Fails?

In a variety of books and learning materials, we're told that if pinging the localhost/loopback address fails, this is a sign of a malfunctioning TCP/IP stack. What we aren't told is why/how this may ...
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Why Windows 7 / PuTTY drop TCP connections even on very brief outages?

I have a small local network that piggybacks on a captive WiFi, and I use ssh on OS X with -oServerAliveInterval=240 and PuTTY 0.62 on Windows 7 Professional for establishing connections to my Linode, ...
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53 views

TCP slowstart by threshold value

I was doing excercises out my book. But there are no answers in the book. This Question is very interesting to me. Does somebody now the answer and why it that answer? A lonely sailor on the Pacific ...
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1answer
55 views

Unstable Transmission Rate in TCP by Packet Loss

Is it true that TCP does not provide a stable transmission rate, because TCP always keep increasing the bandwidth until there is a packet loss?
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1answer
65 views

TCP on the same (server side) source port to multiple (different destinations)?

Question 2 Is it true that a TCP server may send segments with the same (server side) source port to multiple (different destinations)?
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1answer
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Windows 10 dropping TCP connections after 30 seconds

On my Laptop (DELL Latitude E5530) with a completely fresh Windows 10 Enterprise installation any TCP connection gets disconnected after close to exactly 30 seconds. I noticed it first when Skype for ...
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1answer
116 views

Simple program to turn a server into a client and vice-versa?

What would be a simple to use program for Windows that would do the following: Computer A unknown TCP client wants to connect to computer B's unknown TCP server. Both are behind a NAT. Computer A ...
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3answers
298 views

Relation between TCP conversations and TCP streams in Wireshark

I have read about Conversations and TCP Streams but I'm still a bit unsure how they relate to each other if they are on the same layer. For different layers, it's clear to me that e.g. an IP ...
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105 views

Connection timed out when connecting to a remote tcp port

I have deployed my application on Linux CentOS. The app connects to a remote TCP port but it throws a connect timed out exception. I tried to connect it via telnet but the port doesn't respond. I am ...
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How to increase RWIN Value in Windows 10?

We all know that a lot of things have been deprecated and there was also the introduction of auto scaling in earlier windows versions. Right now after using this analyzer http://www.speedguide.net/...
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1answer
89 views

TCP connection only working one way on my local network (trying to connect with Synergy)

I am using Synergy to connect my desktop (GNU/Linux. connected via cable to router) to my laptop (OSX ElCapitan. connected via WiFi). It works like a charm if I use the laptop as the server; From ...
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6answers
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How does a router route connections?

How does a router track connections? When you send a http request it goes to the router which is then sent to another router, etc over the internet; but then how does it know to go to the server, is ...
2
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1answer
82 views

How to list socket options of running processes?

Is there a convenient way (e.g. a readily-available command or a program that I can write using standard system calls) to list socket options (e.g. TCP_NODELAY) of an open TCP socket of some running ...
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2answers
491 views

why TCP window scale values (scaling factor) are different in different hosts?

why TCP window scale values (scaling factor) are different in different hosts? why not make this value the same on all hosts? in theory, this value is between 0-14. what is the practical range for ...
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57 views

Kill TCP connection in VMware ESXi 5

If there anyway to kill a tcp "TIME_WAIT" state connection in VMWare ESXi~ # esxcli network ip connection list Proto Recv Q Send Q Local Address Foreign Address State World ID ...
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1answer
45 views

Configure Wireshark to capture any packages between host machine, and guest (VM)

I'm new to this whole Wireshark thing. I have a VM running inside my local Mac via VMWare Fusion. VM IP Address : 172.16.139.129 Mac IP Address : 10.0.0.4 I want to capture http connection between ...
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114 views

How can one block a port without administrator privileges?

I have found that binding to a port with a Java program prevents other applications from using the port in question. However, if an application is already using the port, a Java program cannot be used ...
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2answers
98 views

Raw TCP on Chrome OS

I have an Acer Chromebook 13, with an ARM processor, and am trying to connect to my friend's server via TCP. I have tried all of the promising web apps for Chrome but they either will not connect or ...
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459 views

DBus over Network (TCP)

I'm trying to communicate with a remote DBus (i.e. IP 10.100.20.101) from a host (i.e. IP 10.100.20.102) - X86_64 platform to ARM development board. I've tried the solutions from here but it caused ...
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Windows 7 frequent download interruption

I just upgraded to Windows 7 Pro from Home Premium, and now almost all downloads (Youtube videos, online games, ftp/http downloads) are interrupted after a random length of time. Sometimes the ...
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2answers
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How can I see 127.0.0.1 traffic on Windows using Wireshark?

Every time I try to filter to just show a specific IP address, I get an error indicating that it is "not an interface or a field." I have no idea what that means. Furthermore, I don’t really see any ...
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What causes these corrupted downloads and spurious retransmissions?

I encountered many corrupted downloads recently. Sometimes compressed files wouldn’t open or checksums would not match. Sometimes images on Websites would just be grey (or a wild mix of colour) after ...
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1answer
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Why are TCP Packets going from my pc to server owned by EdgeCast Networks, Inc.?

I am seeing a lot of entries like this in my Netgear DGN 1000 log for the last few weeks: Wed, 2015-11-04 20:36:56 - TCP Packet - Source:192.168.0.2,63272 Destination:68.232.44.114,80 - [BLOCK] ...
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TCP Dump received from Verizon, along with an abuse notice

Apologies in advance if this Question is not a good fit for your forum, but I hope it is and someone can help. I'm a FIOS customer and received from "abuse@verizon.net" a TCP dump as part of an email ...
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Killing TCP connection on Windows via cmd prompt

There are already at least two similar threads on SU both having either outdated answers or answers that suggest using GUI. Thus the following programs are NOT what I'm looking for: wkillcx - that ...
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2answers
6k 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 ...