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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How to achieve multiple NFS/TCP connections to the same server?

I'm trying to maximize the NFS/TCP bandwidth between a Linux client and a single NFS server over a 10Gbps link. Although each NFS mount has its own device (major/minor), everything comes down to a ...
4
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2answers
1k views

How to reset a tcp connection immediately on both ends on a certain condition using linux netfilter/iptables?

Dear Serverfault community, I have the following problem: I need to reset (disconnect) tcp connections on both network sides immediately if a certain string is encountered in the packet data. I don't ...
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2answers
42 views

A small puzzle about routing

This is a followup to this question I saw on SuperUser, to which no answer has been provided. A user deleted the second route in his routing table, # ip route show default via 192.168.73.1 dev ...
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2answers
115 views

TCP timeout for established connections in Windows

I have the following situation: Application (Firebird DB client) on a client computer opens a TCP connection to server on port 3050 Application crash on client, application terminated netstat on the ...
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2answers
56 views

Run ncat in background

from some time I'm trying to resolve very annoying issue: I need to have simple server which will listen on particular TCP port and throw all information which it recieve to trash. I'm doing it by ...
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2answers
165 views

Can't access server use domain name, got tcp flag RST

I have a http sever provide service to internet, so I configured port forward in router. It’s fine for users access server outside company (URL: _http://mydomain.com:80/). But if the user is inside ...
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2answers
566 views

Solaris: Increase TCP's Initial Congestion Window to 10 segments (tcp slow-start)

How can the Initial Congestion Window be increased to 10? It seems it can be done with TCP_INIT_CWND, but I don't know how to do that.
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2answers
466 views

TCP hang up in interactive sessions

I am experiencing a problem on the intranet of my institution. I am sitting in front of A and trying to connect to server B in another city. My ssh sessions hang up quite often, especially when I ...
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2answers
41 views

SMB / CIFS / Samba Connectionless or Not whilst transfering files?

I have been researching this for a bit, but I have been getting conflicting answers, does samba, from my gatherings, SMB runs on ports TCP & UDP 137-139 & 445. But I have no idea therefore ...
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2answers
299 views

tcp ack delay almost 600ms, is this all right?

As far as I konw, tcp delay ack always 200ms, but now in my production environment it delay almost 600ms, my environment is below: ubuntu 11.04 48G memory 16 core, load not heavy; I catch packet in ...
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1answer
896 views

What do I need to consider when setting TCP idle timeouts?

What's purpose of having a [low] TCP idle timeouts? E.g., why have a 60 second timeout on a firewall or load-balancer? Is it a memory management or /performance optimization thing? Is there a security ...
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1answer
181 views

TCP RST from telnet/ssh daemons when connecting from openvpn

I have LAN_1 and LAN_2 interconnected with an openvpn tunnel terminated ona pair of SOHO routers running busybox. One of the vpn purpose is to allow clients on both LAN_1 and LAN_2, to administer the ...
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1answer
127 views

Linux tool to show connections/s?

Is there a tool/command to show connections per sec? I've tried a few iptraf and iftop but I can't see anything about connection rates.
0
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1answer
281 views

Show real TCP/IP addresses behind Nginx environment

When i execute the command netstat -atun | awk '{print $5}' | cut -d: -f1 | sed -e '/^$/d' |sort | uniq -c | sort -n I see high number of connection assigned to server ip I want to see the real ...
0
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1answer
616 views

pushing apache2 past 1500 concurrent connections

I am trying to scale to 4000 concurrent connections on a ubuntu/apache box. It is 8 core / 64gb ram, so it is not hitting memory or cpu, or any resources for that matter. The problem is with ...
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1answer
343 views

How to view tcp connection errors in apache/ubuntu

I am load testing a ubuntu/apache2 server and after 500 concurrent connections my load testing software is telling me there are connection errors. The errors are not showing up in apache error log. ...
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1answer
286 views

Support of batch mode in tcpkill

I fire tcpkill with destination ip. Example tcpkill host 10.0.2.184 The problem I am facing is that, tcpkill doesn't come out after killing all tcp connection. After killing all tcp connection it ...
0
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1answer
166 views

What packet to ignore to not have ssh terminated on brief connectivity loss?

It seems like sometimes there are some connectivity problems around the edge of our network to certain other networks, and my ssh sessions with some remote servers, which themselves have no ...
0
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1answer
515 views

TCP packets larger than 4 KB don't get a reply from Linux

I'm running Linux 3.2.51 in a virtual machine (192.168.33.15). I'm sending Ethernet frames to it. I'm writing custom software trying to emulate a TCP peer, the other peer is Linux running in the ...
0
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1answer
370 views

TCP packet filter based on TCP sequence

I need to build a test environment with a very precise packet loss based on specific TCP sequence or, optionally, on payload content. I couldn't figure out how to do it with tc or iptables. What tool ...
0
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1answer
1k views

How to increase nginx connections

I am facing the problem of nginx max connection issues. I am not able to increase max active connections(520) made by nginx. Some time it is using whole writing (516) operation connections. and due to ...
0
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1answer
226 views

svnserve -d child process spawning and svn connections under netstat

I see many svnserve -d processes running on my CentOS 6 box, one with the PID 400 and PPID 1 and the rest with PPID 400. I take this to mean the first one is started by init scripts (i know it is) ...
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1answer
178 views

Routing config between internet load balancers and backend

Im facing a problem due my lack of experiencie on routing. I need to config the next things (all run on my computer virtualized, if works, i will pass it to hardware) [internet] ---- ...
0
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1answer
344 views

server dosnt produce syn-ack

I have a small program that take packets from the nfqueue . change the ip.dst to my server dst (and ttl), recalc checksum and return the packet to the nfqueue. The server and the client are linux and ...
0
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1answer
233 views

Socket(TCPIP) Unstable

I have a setup of a SCPI server in a Win7 PC and have 2 other programs talking to it locally(127.0.0.1) over TCPIP socket 5025 and 5029. This worked well and stable in a fresh PC, but when we moved ...
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1answer
280 views

TCP sender and receiver window issues

I just want to clarify some things. Lets say the receiver advertises a window of 2000 bytes. The sender sends a 1500 bytes and receives an ack from receiver with window size 100. The ack does not ...
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1answer
102 views

Windows XP TCP halts after burst on ZMQ channel

I have a ZMQ application the sends a high rate of data over a TCP connection upon start up. The application runs fine on Windows 7 and Server 2003, but on XP it halts shortly after connection. The app ...
0
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1answer
399 views

fast opening and closing connection with a specific port

We have a Main application named "Trevor" installed in 2008R2 machine named "TEAMER12" which is slow now. One more application named "TVS" also running in and found there were many connections per ...
0
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1answer
196 views

Windows 2008 Server ignoring LDAP request

I'm using Windows Server 2008 R2 and Windows NIC teaming. This is an HP server. Firewall disabled. I have 1 application which authenticates via LDAP to AD (TCP 389). (App is located in same VLAN) ...
0
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1answer
402 views

WSAECONNRESET curiousity

How exactly does the TCP stack on windows determine that the connection has been forcibly closed or reset by peer? I know that TCP on Windows by default tries to retransmit an unacknowledged packet 5 ...
0
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1answer
86 views

WebServer Performance Issue

Recently we moved to a new hosting infrastructure and our web site, every 30 min or so, comes to a halt and then recovers ... What we noticed by looking at the performance monitor is that while we ...
0
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1answer
441 views

Benchmarking TCP Server

I've written a very basic TCP-Server based on libevent. Now I would like to test the Server. Is there a tool which generates a lot of connections so that I can check how much concurrent connections ...
0
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1answer
1k views

Improving TCP performance over a network with small packet loss

I’m trying to improve my TCP throughput over a “high delay network”, with some packet drops, between Linux machines. I set tcp_mem, tcp_wmem and tcp_rmem to “8192 20530752 20530752”. I set rmem_max, ...
0
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1answer
273 views

Detecting TCP/IP connection drop issues in my application

I have a desktop application which talks to a server using TCP/IP. It was working before but now we are running into an issue. The log message on the server shows that the socket is disconnected after ...
0
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1answer
141 views

What to check when nginx is fast to serve requests once connected, but slow to connect?

There is sometimes a 1-2 second delay when connecting to port 80 (nginx) over the public interface. It occurs 50% of the time. Once connected nginx serves all requests, including fastcgi proxy ...
0
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1answer
162 views

Computer Networks Question

Consider the effect of using slow start on a line with a 10-msec round-trip time and no congestion. Assume the maximum segment size is 4KB and the threshold is set to 16KB initially in congestion ...
0
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1answer
189 views

sliding window protocol?

I understand how sliding window protocol makes the network reliable. But how can it control the flow of data?
0
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1answer
150 views

No transmission via IP

I'm using netstat on Win XP to check protocol transmission details for TCP, IP, and ICMP. There is transmission only in TCP. No transmission in ICMP is understandable since it's for errors and I ...
0
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1answer
535 views

Strange 2Mbps limit for single tcp connection on 24Mbps ADSL2+

I've D-Link DSL-2500U/BRU/D, ADSL mode is "ADSL2+ AnnexM EU-56", configured as bridge and connected to linux (Gentoo) workstation. Line is good enough, I've stable speed 2.09MiB/sec (i.e. about ...
0
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1answer
822 views

Memory Pressure Protection Feature for TCP Stack - Provided by Microsoft Security Update KB967723

We've been having a lot of funky issues with some of our web based applications that allow clients to submit lot of image files to our servers. Lots of ports are used in the process. ...
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1answer
71 views

What are the ports needed for L2TP VPN on Mac OS X Server 5.0.15?

I'm configuring a Mac as a server with a VPN service. So, I opened the ports listed as used by VPN in Apple documentation: UDP 500 -> 500 (+ESP and AH) UDP 4500 -> 4500 Any UDP -> 1701 (I got to ...
-1
votes
1answer
65 views

random server timeout connections

I am searching for a solution for this issue for 2 days now. I have a centos server, and I get random timeout connections error, about 10-20% of the times. yesterday it happened to one of my users, ...
-1
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1answer
58 views

Can TCP be used like UDP by simply not sending ACK?

Assuming both client & server cooperated, could you emulate the functionality of UDP by not sending ACK packets, and not sending retransmissions? Or would most routers somehow bork the process if ...
-1
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1answer
127 views

How to redirect all incoming packets to sniffer in Linux using iptables?

I need to redirect all incoming tcp packets from eth0 to current host (change ip address from 1.1.1.1 to 1.1.1.2) and outgoing tcp packets from sniffer from eth1 to another host(from 2.2.2.2 to ...
-1
votes
1answer
145 views

TCP Server Memory management: #Connections Vs. #Requests

Given that, there is no theoretical limit to number of concurrent TCP connections a Windows 2008 server can handle. Only thing will happen is, with each connection there will be memory consumption in ...
-1
votes
1answer
1k views

How to enable/disable TCP DELAYED ACK parameter on SUSE linux?

I want to disable TCP DELAYED ACK parameter on SUSE Linux Enterprise Server for some performance tuning operations. I have used sysctl command but it does not list this parameter. also in SUSE ...
-1
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1answer
338 views

iptables NAT Forward 443 Port DNAT,SNAT failing

I'm trying to setup a proxy server that handles http and forwards https to the webserver. Client > Proxy > httpd I added the rules: iptables -t nat -I PREROUTING -i eth1 -p tcp -m tcp --dport ...
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1answer
1k views

How to enable jumbo frame and large TCP on Windows Server 2008

I needed to enable the jumbo frame 9000 in network setting, and I have already done that. I still need to enable large TCP on Windows Server 2008, but how do I do that?
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1answer
421 views

IIS listening 127.0.0.1 instead 0.0.0.0

I configure binding on my IIS 7 server like: ip address: All Unassigned port: 8080 but in netstat -aon command see only 127.0.0.1:8080 instead 0.0.0.0:8080(which I would like) (0.0.0.0:8080 is ...
-3
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1answer
792 views

how to open tcp port in ubuntu

I have a ubuntu server How can i open a port ? I have flushed the iptables and off'ed ufw Provide me steps how to open a tcp port