The Transport Control Protocol (TCP) is a low-level part of the protocol stack used by the Internet. It sits directly above the IP layer and is responsible for making sure that dropped packets are resent.

learn more… | top users | synonyms

3
votes
2answers
415 views

iptables port forwarding

I have a CentOS server with Java/J2EE(Tomcat) installed on TCP port 8080. I have two interfaces, eth0 and lo. I need to forward all incoming connection on TCP port 80 to 8080. I tried doing the ...
4
votes
1answer
67 views

How to investigate a random reset on TCP client port connected via loopback interface to a server

I have a test suite which initializes a server on the localhost and then runs thousands of stress tests which include starting and stopping clients connecting to this local server on same machine. I ...
3
votes
1answer
101 views

detect process that executes portscans

I have to administer an ubuntu 12.04 server, where there seem to go portscans to the whole subnet. How can I find out the process that does the scans? pstree init─┬─acpid ...
2
votes
1answer
603 views

Port Mirroring in Fedora?

I have set up an application that listens constantly to a port for network packets, and I would like to create another one that receives the same network packets ( for use as a test bed). Getting the ...
1
vote
1answer
368 views

How to limit all tcp traffic to the network interface the session was initiated on?

I have an embedded linux system with two network interfaces (lan0, wlan0) that are configured to the same subnet. A server on this system accepts tcp connections on both interfaces. How I can assure ...
0
votes
1answer
85 views

What are the other congestion control algorithms specially designed for lossy Wireless Networks like LTE and WiMax?

I am trying different congestion control algorithms for getting maximum throughput and minimum delay across my setup for TCP flow.Please suggest other available algorithms apart from Veno, ...
4
votes
0answers
174 views

Socksifying a qemu-kvm using tsocks

I'm trying to socksify a qemu-kvm using tsocks, but I have no success. I don't know if qemu access directly the hardware, skipping the OS or something like that, but I wasn't able to do this feat. ...
2
votes
0answers
54 views

nc -l in background closes immediately (nc -l 1234 &)

When I put this nc -l 12345 >nc_out in a shell script, run it and then connect from other shell using telnet, it allows me to type some text and have it end up in nc_out. But if I start nc in ...
2
votes
0answers
20 views

Discovering the Cause of tcp rcvpruned?

I get a few rcv pruned packets on my load balancers a day and I would like to know what the cause is: However, based on my tcp_mem vs tcp_mem usage I don't understand why some packets are being ...
2
votes
0answers
198 views

graph TCP connection performance based on `ss -i`

A nearby question has brought to my attention the ss utility on Linux, another utility to investigate sockets. It would appear that it may be a great tool to monitor the performance of, say, an ssh ...
2
votes
0answers
74 views

Why isn't hydra being disconnected?

I have SSHD running on port 5800 on some machine. (It is a my machine at home.) If I run this manually in a terminal: # ssh someIP -p 5800 The connection is lost because I am disconnected after 3 ...
1
vote
0answers
35 views

tcpdump not capturing http or tcp/ssl traffic

I have been trying to learn tcpdump and I am using this command to attempt to monitor my network: sudo tcpdump -I -i en1 But this gives me a bunch of stuff I don't want, so I used this version to ...
1
vote
0answers
107 views

Improving TCP performance over a gigabit network

I have two machines both network cards speed is 10Gbps. The inbound bandwidth between the two machines is 10Gbps, the outbound bandwidth internet bandwidth is 500Mpbs. Both machines are using public ...
1
vote
0answers
63 views

IPTables 1.4.7 dropped allowed packet

When looking in the /var/log/messages file I found this line: May 23 10:56:02 localhost kernel: IP4T Invalid TCP flags IN=eth0 OUT= MAC=70:5a:b6:ec:95:6b:00:23:48:ad:b0:a4:08:00 SRC=A.B.C.D ...
1
vote
0answers
57 views

Is this kernel warning a major problem that needs my attention?

Our Linux based Thecus N12000 NAS recently experienced this message in its dmesg log. [2014-05-21 11:34:56] ------------[ cut here ]------------ [2014-05-21 11:34:56] WARNING: at ...
1
vote
0answers
86 views

Command for finding open ports

On my linux servers I have this alias set: alias ns="sudo lsof -Pi|grep -v ESTABL|grep -v CLOSED|grep -v -e '->' | tr -s ' ' '\t' | awk '{print $3 "\t" $8 "\t" $5 "\t" $9 "\t" $1}'| column ...
1
vote
0answers
279 views

How to redirect/forward between a tun/tap device and a socket using linux tools?

I have a socks5 proxy that is bind to eth0. It opens two ports, Port1 is used to connect to remote (for example a http server), Port2 is to listen for clients to connect. Then I created a tun device. ...
1
vote
0answers
55 views

configure allowed_tcp_congestion_control via config files in linux kernel

I am trying to come up with a custom set of TCP congestion control variants as part of the tcp_allowed_congestion_control. I do have multiple variants on my tcp_available_congestion_control list but ...
1
vote
0answers
50 views

Can we Bring Up eth1 after removing e1000e modules?

I am trying to setup TCP in RTnet. I am not sure whether its possible. I read that RTnet is not supporting TCP. Is that so? So now I am trying to setup rteth0 as server and eth1 as client. To setup ...
0
votes
0answers
46 views

How to set sctp_nodelay to enable piggybacking while replying back

Problem: We are hosting a telecom application that receives traffic from the network at > 500 TPS. The packets are piggybacked so each sctp packet contains multiple application layer packets lets say ...
0
votes
0answers
28 views

Dropping unnecesery TCP connections

I use Enigma based satbox as live stream source. I noticed that sometimes connection established from my server based streaming application to satbox is still keep as ESTABLISHED, even after stopping ...
0
votes
0answers
48 views

Is it possible to move established connections on one port, to another without dropping data?

this problem has been bugging me for a couple of days now. I can't figure out a good enough solution using iptables without having dropped packets. So here is the back story. Say I have a client ...
0
votes
0answers
110 views

irc connection timeout problem

I am using tcpredir to connect to freenode server via port 6665 for some firewall difficulties: server:~# redir --lport=6665 --cport=6665 --caddr=irc.freenode.net and recently i faced a problem, i ...
0
votes
0answers
86 views

How to make Network alive but speed low, slow for upload, download?

I have own application written (Python, Java) which does upload/download for streaming. Now in my local office network and home network setup i can't simulate slow/low latency network (as a result i ...
0
votes
0answers
202 views

No ports can be found using port scan

Problem: I have a laptop and a server (Home-Server) with fc17. They are both using the desktop environment. I am trying to set up a VNC server on Home-Server so that I can set everything up without ...