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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Samba not connectable “Go away, we're not home”

I'm having an issue connecting to my dedicated server using samba. The server is a debian (squeeze) box running a samba server, only small modifications have been made to the default config and the ...
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10 views

Using DJB's tcpclient or tcpcat bidirectionally

Can someone post an example on how to use DJB's tcpclient bidirectionally? We need to read from Tor's ControlPort as well as write to Tor's ControlPort. A "file" that is open for both, reading and ...
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1k views

tcp port numbers reused on wireshark

I used raw socket to build a tcp client program on machine A to reproduce tcp 3-way handshake with a simple regular tcp server on machine B I captured packets on the client host and server host, and ...
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503 views

MySQL crashes when connecting from localhost with tcp (UNIX sockets work)

I have Ubuntu 12.04 running MySQL server 5.5.24. I can connect with mysql --user root -p. status shows me : ... Connection: Localhost via UNIX socket ... When I try to connect with mysql --host ...
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56 views

Most network protocols occasionally fail

My Windows 7/64 machine has suddenly started to act funny. Everything will be running fine, when suddenly most network access methods will fail. These things continue to work: Accessing network ...
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13 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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43 views

What's wrong with this tcpdump syntax?

sudo tcpdump -i ath1 -s 0 -nne "(type mgt and subtype beacon)" Can anyone help me? I was following a tutorial at http://wiki.secarmour.com/2013/09/capture-wireless-traffic.html but seems I got ...
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57 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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220 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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89 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. ...
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86 views

Delete Hung TCP Sessions with SNMP

What I am trying to do, and failing horribly, is to close a TCP connection... I am trying to do this via SNMP and the functionality that is provided in the TCP MIB. First, I look at all the ...
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116 views

Windows 7 / PuTTY drop IPv6 TCP connections on brief outages

This is an IPv6-version of the following question: Why Windows 7 / PuTTY drop TCP connections even on very brief outages? After moving from IPv4 to IPv6, I've noticed that my IPv6 connections would ...
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111 views

No response received from github ssh randomly

My git pull started to stop working randomly with this error $ git pull ssh: connect to host github.com port 22: Connection timed out fatal: The remote end hung up unexpectedly I tried debugging ...
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180 views

TCP/IP resets (Linux, SSH, RDP, ADSL router)

I have an ADSL router (model Pirelli DR A226G) that seems to cause dropped tcp/ip connections (not ADSL connection per se). I have tracked it using Wireshark and captured a few cases and they always ...
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616 views

connect to a serial device via TCP socket

My setup is this: serial device ttyUSB0 connected to laptop A software that opens TCP socket to listen and write to, also runs on laptop A (linux) My goal is to pipe data from/to serial device ...
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171 views

Load TCP New Reno protocol

I am doing some test of the congestion control protocols and I cannot find how to load the protocol New Reno. I loaded a lot of protocols like Reno, Vegas, Hybla, Bic, Cubic, etc using the sysctl ...
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445 views

How to use NetLimiter to block inbound TCP traffic?

I'm using NetLimiter to block TCP traffic. (Rule type: Firewall, Direction: In, Action: Deny) I can block outbound, but not inbound. You can try blocking inbound TCP on Chrome to see it is not ...
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213 views

Artificial network delay tcp/udp (bigger ping) for defined application? (windows)

I have a game where people can easy detect who i am looking at my ping, i want to make my ping highter. How can i set network delay for all network connections for defined application?
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221 views

Tunnelling TCP connection through NAT

My server is in my school's NAT and my desktop computer is in my home NAT. I want to SSH to my server from home. I normally used school's VPN, but recently for some reason I can't. So I'm looking for ...
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115 views

TCP connection not timing out, visible on server but not client

On the server both the application and netstat show a connection open. The client however lists no such connection, and the client software is definitely stopped. I'd already lowered the TCP ...
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111 views

How to route none http request in pound.cfg

I'm trying to route all request that point on the port 3050 to another host, here is what i usually write in the /etc/pound/pound.cfg: ListenHTTP Address 10.165.30.58 Port 3050 ...
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348 views

Can not open port 6000 windows xp

I am trying to connect to macincloud using their software and can not. They told me the reason is port 6000 is not open. I spent 3 hours on the phone today with ATT making sure the 6000 port was open ...
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743 views

Iptables port redirecting. Rule doesn't work or show up in iptabels

I'm trying to redirect some incoming TCP traffic on port 443 to port 999 with iptables in an Ubuntu VM. I am using sudo iptables -t nat -A PREROUTING -p tcp --destination-port 443 -j REDIRECT ...
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337 views

Create a VNC proxy with authentication

We have a bunch of VNC servers located on our local network. We wish to give external customers access to these VNC servers, via some sort of "middle-man" software solution which can handle ...
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403 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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384 views

HP G61 Notebook: TCP seems to be dead

Can't say I'm much of a Windows expert, but this is somewhat of a weird occurence. I'm in front of a HP G61 Notebook laptop with Win7 that has connectivity problems. I mean that it's connected to the ...
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8 views

What is the timeframe used, for TCPBacklogDrop value calculation in netstat

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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3 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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16 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: ...
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18 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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42 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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25 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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28 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 ...
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111 views

Disable TCP keepalive on RHEL6

Is it possible to disable TCP keepalive on RHEL6? I know the kernel parameters for tuning TCP keepalive timeout are as follows: net.ipv4.tcp_keepalive_time net.ipv4.tcp_keepalive_intvl ...
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59 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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25 views

TCP 'ip route change' not working to change cwnd on Linux

I'm trying to change the cwnd using 'ip route change'. The command I'm using: ip route change 172.16.231.0/24 dev eth0 proto kernel scope link src 172.16.231.26 cwnd lock 7. The first time I run ...
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109 views

not all packets forwarded by pptp VPN server

I have the following setup: +------+ +---------+ ppp0---------+ |router| | A +-----+---+-----+ B | | R | ...
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88 views

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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23 views

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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564 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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51 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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42 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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28 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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104 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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55 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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21 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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139 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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45 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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144 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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58 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?