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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Connection Oriented Transport Protocol

Does anyone have an idea about a software for Linux that uses COTP (ISO 8073) protocol ? note : software that runs COTP over TCP , doesn't matter what is the functionality of the software i just need ...
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How do I delay tcp traffic on a socket?

I would like to test the interactions between a client program and a server program for race conditions. They connect to each other via tcp. The client does blocking calls to the server on multiple ...
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SFTP upload and download speed difference

I have two Solaris box, I am using SFTP to transfer file of 1063 MB. when I do fire get (get file from server) speed is approx. 270KB/s when I do fire put (put file on server) speed is approx. ...
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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 ...
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44 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 ...
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40 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 ...
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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@" ...
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1answer
24 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 ...
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31 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 ...
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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 ...
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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 ...
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33 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 ...
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19 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 ...
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1answer
51 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 ...
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2answers
49 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
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1answer
89 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 ...
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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 ...
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16 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 ...
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1answer
57 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 ...
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1answer
63 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 ...
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1answer
267 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 ...
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1answer
90 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 ...
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2answers
165 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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2answers
126 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 ...
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60 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 ...
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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 ...
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2answers
80 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 ...
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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 ...
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56 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 ...
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1answer
57 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 ...
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1answer
30 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 ...
4
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1answer
447 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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1answer
70 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 ...
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1answer
42 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 ...
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98 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 ...
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38 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 ...
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527 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 ...
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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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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. ...
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1answer
86 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 ...
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1answer
52 views

Simulate tcp window full on ubuntu

I have 2 ubuntu boxes. In between them is a firewall. I am trying to simulate tcp window full condition or in other words, I want the ubuntu server to send a tcp window full flag to client. Here are ...
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2answers
213 views

Windows Server 2012 cannot access web sites

I have a Windows Server 2012 that has gone a little crazy in the last 24 hours. It can't access any websites, internal to the network or on the web. I can ping google.ca for example and it resolves ...
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3answers
922 views

How to force a process transmit over UDP instead of TCP?

I 'm running an ffserver process on a Linux machine, in order to achieve video streaming via ffmpeg. However, there is a delay on video streaming. On ffserver configuration file I define Port 8090. ...
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1answer
54 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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30 views

UDP causing problems with other connections

I have implemented a file transfer program on Windows 64-bit platform using winsock API. I am using a 1Gbps connection. When I transfer files using TCP protocol, I am getting only 320 Mbps. when I ...
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1answer
125 views

Session layer in OSI vs TCP/IP

I'm sort of confused here: According to several illustrations I've seen and material from Cisco the session layer from OSI is part of the application layer in TCP/IP. This makes no sense to me since ...
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2answers
42 views

TCP/IP minimal size

I am using a high level language on a PC to send a message via TCP/IP to a remote device which is an embedded device. I am sending relatively small messages (< 255 bytes). I must assume that there ...
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1answer
207 views

Why does writing IP addresses this alternate way work, and is there a practical use case for it? [duplicate]

Recently I saw an incorrectly typed telnet command, and I saw that "regular" numbers were interpreted to IP addresses. I tried this myself in Windows and the same behavior is shown there, so obviously ...
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2answers
63 views

Free official documentation for cables and models? [closed]

I've been looking through the ISO and IEEE sites for official documentation on the Open Systems Interconnection (OSI) model, TCP, and a range of cable standards (5/5e/6). However, other than on the ...
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114 views

Is DNS query a UDP or TCP?

I know that when we first type an address on the URL and enter. The DNS query starts. I don't who initiates, but my guess is application will only initiate the DNS query. The DNS query already knows ...