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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618 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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108 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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24 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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263 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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2k 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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339 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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643 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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320 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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34 views

unknown local address in TCPView

I'm looking at connections in TCPView, and I'm seeing "red5" in the "local address" column. This doesn't appear to match any computers on my local network, the names of which I have seen from time to ...
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16 views

TCP Rentransmission when connecting sepcific website

Question: I'm an administrator of couple of websites. Every website is set on the same server provided by linuxpl.com. The server ip is: 95.211.176.132. The problem is, when I try to reach the server ...
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52 views

iptables SNAT target and TCP ACK packets

I need to establish a TCP connection where the client is spoofing its IP for all outgoing traffic. My first attempt was to add a rule to the POSTROUTING chain like so: iptables -t nat -A POSTROUTING ...
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94 views

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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36 views

Outgoing traffic using Local(internal) PC IP address to a DDNS hostname

Sorry if the title is confusing. I have two devices connected through the internet. I need device A (Windows Server 2012) to send data down to device B, but unfortunately device B does not have a ...
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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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161 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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35 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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485 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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649 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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175 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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197 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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138 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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234 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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283 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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4k 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 ...
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1k 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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294 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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958 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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291 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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143 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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127 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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461 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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903 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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378 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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420 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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7 views

Direct host SMB - Ports

It's well known that SMB uses port 445, and that NetBIOS uses ports 137-139. However, according to all official MS documentation (https://support.microsoft.com/en-us/kb/204279), SMB uses both TCP and ...
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27 views

TCP congestion control

I was curious to know which are the default TCP congestion control method used in latest version of MacOSx, linux kernal, windows 8, windows 7 and windows xp. Does it use newreno or anything newer?
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6 views

pfSense does not close connections coming from LAN

I created a NAT rule that redirects external_ip:1234 of modem (pfSense itself) to 192.168.1.100:1234. I also wrote a server application which listens for connections on 192.168.1.100:1234. When I ...
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21 views

How to add latency to TCP packets?

I have tried netem and wanem neither seem to be affecting the TCP packets. How can I add latency to TCP packets?
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14 views

tcp sesssion duplicate acknowledgement and retransmission

Please help in understanding why the receiver keeps sending duplicate acknowledgement yet the senders keeps sending old packet sequence (re transmitting of old packet seq)
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22 views

Duplicate and retransmission

Please help me understand why the receiver keeps sending duplicate acknowledgements, yet the senders keeps sending old packet sequence (re-transmitting of old packet seq) in the below capture: Please ...
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45 views

Drop resilient tcp tunnel

I'm looking for a tcp tunnel that can provide connection drop resilient TCP connections to my VPS. Currently when I have some tool connected to my VPS and I switch from Wifi to LAN or my internet dies ...
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82 views

No connection could be made because the target machine actively refused it

On Windows machine, I start a server on port 62325 $ netsh firewall show state shows: Ports currently open on all network interfaces: Port Protocol Version Program ...
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22 views

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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20 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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44 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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37 views

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 ...
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14 views

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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43 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 ...