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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30 views

haproxy- setting up an TCP connection cache for an HTTP server

I am trying to setup a local TCP connection cache to provide access to a remote HTTP server for multiple local applications. I have started to configure haproxy to do this: global log ...
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57 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 ...
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16 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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273 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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564 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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57 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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6 views

Route only on output chain?

I have two machines A and B. I want to send iperf traffic from A to B, but first have it route through a userspace program on A. I did this with a tunneling device: therefore, I used the command ip ...
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97 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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92 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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29 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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235 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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95 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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383 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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116 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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123 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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129 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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175 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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239 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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788 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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237 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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657 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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254 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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121 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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119 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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400 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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857 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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348 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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471 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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404 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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6 views

One side TCP ESTABLISHED connection

On the Server 10.10.3.171 I use netstat to find clients : $ netstat -ant | grep 24225 | grep 10.10.3.169 tcp 0 0 10.10.3.171:24225 10.10.3.169:58591 ESTABLISHED tcp 0 ...
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14 views

How much upstream traffic should a transfer over TCP produce

When a file is downloaded via some TCP-based protocol, there is also data flowing in the other direction – acknowledgement packages etc. Now if I watch some network monitor, I wonder if all of the ...
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46 views

Does Fast Retransmit and Retransmission Timer work at the same time?

When Fast Retransmit is implemented, if I received packet 1, then I will send an ACK that says I need packet 2, and then if I received packet 3, I will send a duplicate ACK that says that I need ...
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24 views

TCP Retransmission on the receiver side

How does Wireshark knows that a packet on the receiver side is being retransmitted. I mean it makes sense on the sender side: Wireshark sees two identical packets (with the same sequence number) being ...
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18 views

How to change the current TCP timestamp value for Linux?

Linux normally sends a TSval field that corresponds to the current uptime. I would like to overwrite this with a user-specified value. # 4 hours after boot: > outgoing TCP packets have TSval ...
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24 views

Tcp connection target machine actively refused

I have a simple TCP client/server program on two laptops. The server should work fine as I use "netstat -anb" and the server shows up as listening, "0.0.0.0:102", then my client connection failed, ...
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34 views

Connection interruptions on Debian router, possibly due to excessive duplicate ACKs?

I have a Debian server as a house router, which for a year has been working flawlessly. However, I recently moved and switched service providers from FiOS to Comcast, and possibly as a result am ...
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30 views

iptables block access to all ports except 53 (tcp,udp) from one IP address

how can i block all ports from one IP address except the port 53 TCP,UDP? example: ip 192.168.0.15 access only port 53 (udp,tcp). thank you.
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42 views

How to tunnel UDP traffic over Tor?

I know that Tor does not support UDP for now . But I came upon certain application Onion Cat .But I don't know if it work or not . Is there any other procedure ? Is that even possible ? Please guide ...
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26 views

Simultaneous TCP Keep Alive requests no second ack

I have a TCP server running on port 6524 and a client running on port x11 on the same system (Linux sys-111 2.6.32-431.29.2.el6.x86_64). Both these send TCP Keep alive messages to keep the connection ...
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28 views

Monitor TCP port traffic and get a sound alert when a specific text string is found on Windows

I need to watch a port for several hours and make an audible alert whenever a specific string comes through. Windows only. Is this possible with Wireshark or another sniffer tool or maybe a sniffer ...
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100 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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45 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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58 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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16 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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28 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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64 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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93 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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165 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 ...