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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17
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3answers
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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 ...
0
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0answers
14 views

How to interface with iOS lockdownd [migrated]

I used nmap to portscan my iPod Touch, and found a single port open, which was port 62078, labeled as "iphone-sync". I did some research, and found that the proccess behind it was a program called ...
0
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0answers
38 views

Linux message: Possible SYN flooding on port 25. Sending cookies

I have a Linux CentOS server online. At my console this message appeared: possible possible SYN flooding on port 25. Sending cookies. See SYN flood and SYN cookies. I have done an Apache JMeter ...
1
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1answer
578 views

Network issues, resolving host

My network connection randomly drops for a 5 minutes or so when I'm online. It always happens when I boot up my computer. I can tell because it says:resolving host in Chrome and I can't ping any ...
1
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1answer
38 views

Utility to monitor a TCP connection for drops

I found some similar questions, but not quite like this, so am going ahead and posting. I use a replication product at a client site. We are running a Windows 2003/2008 server environment. It is ...
0
votes
1answer
50 views

How to set permament TCP Windows Size in Windows XP

I'm checking real throughput of my network using iperf/jperf. Test with speedtest.net shows 25/10 - but jperf shows only 5. So I change in jperf the TCP Window Size into 256K - and now jperf shows ...
0
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0answers
11 views

How do i control a epson projector using putty

Currently i have been messing with a Epson emp 7900, trying to get it to be controlled by a python script. I have currently got a problem where if i send "PWR OFF" it will return "ESC/VP.net@" ...
1
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4answers
5k 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 ...
-1
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1answer
22 views

How can my server announce its presence to everyone in the network [closed]

The situation is as follows. I want to have an application running on a server. All of the desktops in the company has to connect to it. But I do not want the IP address of the server to be hard coded ...
1
vote
1answer
632 views

How to listen to all ports (udp and tcp) or make them all appear open in Debian

I got an external Debian server. The problem is that my university campus doesn't allow connections to go outside when the port is different than TCP port 22, 80, 443, or UDP port 123. I tested them ...
0
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0answers
29 views

Multipath tcp application-level performance measurement

I am working on a project related to Multipath tcp and I want to measure the goodput and the RTT at the application level. I don't want to use a traditional tool(netperf, iperf, ...) and I want to ...
0
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0answers
25 views

No response to ping of specific size

ping <anything> -s 473 does not receive a single reply. ping <anything> -s 476 works, as well as ping <anything> -s 472 but no size inbetween. What could be the reasons for ...
1
vote
1answer
32 views

Redirect ip to another page

i have a modem Dlink DSL-2730U i want to make this modem redirect some ip to another page or to another ip example : i have this ip : 123.456.7.9 i want to redirect it to 8.8.8.8 from ...
0
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0answers
30 views

iptables error “FIX ME! implement getprotobyname() bionic/libc/bionic/stubs.c”

When I do this rule, the error shows up iptables -A INPUT -p tcp -m tcp -m multiport ! --dports 80,443 -j DROP I've also found some solutions. getprotobyname() just converts protocol names like tcp ...
0
votes
0answers
16 views

Inconsistent connection to Websocket on embedded device

I am trying to set up a basic Websocket echo server on an embedded device. I'm testing the server through a very basic webpage, which simply connects upon load and sends a short message ("test") and ...
0
votes
1answer
47 views

Need Help Troubleshooting Network Issue (Client TCP Connections Stuck in FIN_WAIT_2)

(Note: I originally asked this question on the "Network Engineering" side, but a moderator there rejected it as "off topic" and told me to ask here instead.) I am running a video surveillance server ...
2
votes
5answers
23k views

Inbound TCP connection limit in Windows 7

I've done a bit of searching on the internet trying to find out whether there is an INBOUND TCP connection limit on Windows 7. We're writing a server product which processes data from a number of ...
-1
votes
2answers
48 views

Is there a simple audio player that can be remote controlled with UDP or TCP commands? [closed]

Is there a simple audio player that can be remote controlled with UDP or TCP commands? The control needed is very simple: Stop Play Pause Volume up Volume down Next Track Previous Track
1
vote
1answer
54 views

TCP vs UDP. Sending data on a closed port

I try to understand differences between TCP and UDP packet on the error-checking. I know that UDP packets are connectionless and doesn't care that the packet will arrive the destination safely. And ...
0
votes
1answer
72 views

Websocket handshake response not forwarded from TCP to client

I am trying to create a websocket server. I can see the websocket client's opening handhshake. My response to it is received by the client laptop (I can see this on wireshark). So the TCP connection ...
1
vote
0answers
37 views

Is it possible to edit TCP and UDP packets?

Is it possible to edit the UDP and TCP packets a program sends? For example, we have a program that sends some information to its server. But we don't want to send some information that might be ...
0
votes
0answers
14 views

Tons of connections to TCP 135 on another host on the LAN

I am facing a scenario where one server has tons of established connections to port 135 on the DB server on the same subnet. So when I do netstat -nap tcp, I got pages of pages followings, random ...
0
votes
1answer
61 views

Problems with network after using a socks proxy

I was playing around with SSH and trying to route traffic through my laptop. In the end I succeeeded, however I seem to have messed up my network. I only used ssh and played around with both -D and -L ...
1
vote
1answer
222 views

How to send data to tcp server from command prompt [closed]

I am a java developer and quite aware of socket programming in java.I have a tcp server running my localmachine.I can write java codes for client and check communication between server and client.But ...
2
votes
1answer
77 views

Benchmark maximum number of TCP connections on Windows Server 2012

I am wrestling with deploying an application on Windows Server 2012. The problem is that after accepting about ~2000 TCP connections it fails to accept more. And I need much more. We have 8 cores, 16 ...
2
votes
3answers
8k views

Subnet mask of 255.255.255.255

I have a subnet mask of 255.255.255.255.( Why is my subnet mask 255.255.255.255?). I refer that from the above question that it is as good as each computer is on its own network and cant interact ...
0
votes
2answers
144 views

Why are some tcp packets with the RST flag classified as new incoming connection?

While looking through my iptables log, I keep observing periodically incoming connections with the RESET flag being set from a few ip addresses within my ISP's network. This is a sample tcpdump on one ...
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votes
2answers
114 views

eMule not connected

I'm using eMule v0.50a on Windows 7. After installation, I clicked 'connect' It is not connected. Please see the attached screenshot. It reads 'eD2K:Connecting, Kad:Connecting | Preparing' How can I ...
0
votes
2answers
73 views

Host local USB printer via port 9100 TCP

Is there a way to share a printer plugged into a PC running Windows 8.1 via USB over TCP port 9100? I have a piece of software here that only prints to such network printers and is not capable of ...
0
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0answers
55 views

Ethernet port on Linux machine not recognizing ethernet connection with embedded device

I have an atmel at91sam7x256 microcontroller that I would like to use for a TCP/IP communication. The very first step of my project is to be able to "ping" my board given its IP address. I have its IP ...
0
votes
1answer
30 views

Ethernet port re-transmission frequently

We have a laptop that uses its Ethernet port to connect to a device-local network, and wireless for Internet. Recently we installed Wireshark to diagnose some network problem. We found a lot of TCP ...
0
votes
2answers
1k views

What is the “-nolisten tcp” parameter for X

I have just found that my latest kubuntu comes preconfigured with the following: in directory /etc/X11/xinit there is xserverrc #!/bin/sh exec /usr/bin/X -nolisten tcp "$@" But the -nolisten tcp ...
18
votes
4answers
46k 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
votes
2answers
790 views

Capture TCP communication on a specific port using wireshark

Hi i have build a simple TCP server which listens on port 9999 and has an IP address 202.168.66.1 i have a TCP client which has the same ip address and connects to the server on the said port. Now ...
0
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0answers
38 views

Hiding port number from address.

I have centos 6.5 running some web apps. Currently due the following port forwarding rules, I am only able to access my public content using 127.0.0.1:8080/ Is there anyone to just use 127.0.0.1 ...
1
vote
1answer
54 views

How are ports and URI schemes handled by a tcp/ip server?

I am working with the lwip tcp/ip stack on an embedded device, and I'm trying to understand how it all works. I've been looking through the documentation and code, but I'm confused by how ports and ...
0
votes
1answer
29 views

How can I turn on ECN for Mac OSX?

I'd like to run some networking tests with Mac OSX 10.8 and using the ECN option. However I cannot find any documentation on how to configure it. Does anybody know how to alter Mac OSX TCP networking ...
0
votes
2answers
50 views

No Internet access when second dial-up connection in Windows 7

I have a dial-up connection set apart from my normal internet access. When I connect to that dial-up , I loose Internet access (from the 1st network). When the dial-up is not active, Internet works ...
0
votes
1answer
221 views

How can I detect long-lived connections and mark them for shaping

I would like to detect TCP connections which have been open for more than one minute (or for greater than N bytes, or M packets), so I can classify them as bulk traffic ("downloads") and de-prioritise ...
4
votes
1answer
364 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 ...
1
vote
1answer
67 views

Why HTTP response is split in 2 parts: header and body?

I'm trying to understand why a single HTTP response is split in 2 parts in the following setup: Requested resource is protected by HTTP Digest Authentication on server side. Communication is ...
2
votes
4answers
683 views

Difference between the reliable delivery by link protocols and by TCP

There is a quote I forgot from which network book I copied long time ago. Some link-layer protocols provide reliable delivery on a link basis, i.e., from transmitting node, over one link, to ...
0
votes
1answer
41 views

How to add code into the linux kernel?

I am studying how to analyse and evaluate the TCP/IP protocol stack of Linux. My goal is to study the performance of the tcp/ip protocol stack as a whole, to study the time cost of each layer and ...
23
votes
12answers
43k 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 ...
1
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0answers
87 views

Iperf tests in reverse direction

I used iperf to measure the max throughput for TCP connection between two ubuntu machines. Both the machines were directly connected be means of a 1Gbps cable. When I performed iperf tests i obtained ...
0
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0answers
37 views

How to use netperf on specific NIC port?

I have two servers, SERVER and CLIENT and each server has its own onboard 1 GbE ports, and its own NIC with a 10 GbE port. SERVER and CLIENT are interconnected on both a 1 GbE switch (administrative ...
0
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0answers
477 views

How to send message to virtual serial port created with socat?

I am using socat to create a virtual serial port on linux socat -d -d PTY,raw,echo=0,link=/dev/ttyVA00 PTY,raw,echo=0,link=/dev/ttyVB00 which prints socat[31640] N PTY is /dev/pts/2 socat[31640] N ...
0
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0answers
27 views

Setting/clearing packet's TCP flags with iptables

I know iptables can match packets with certain TCP flags using --tcp-flags. But how do I set or clear some flags on a matched IPv4 packet?
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0answers
55 views

why the ping doesn't get a reply?

I have an embedded board that has the CFE, a minimal loader. I have a host machine - linux FC16, where I am running a dhcpd server. My interface is p3p1. Here are the details of the ifcfg-p3p1. ...
0
votes
1answer
76 views

Restrict SSH server tunneling port

I have a SSH server running OpenSSH. I want to use it to setup a SOCKS server so that my friends in China can use it to access websites such as twitter. I want to enforce two restrictions: 1. no shell ...