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.

learn more… | top users | synonyms

3
votes
1answer
116 views

Default TCP connection backlog value in Windows

Which is the default connection backlog value for TCP in Windows? I have tried to find it but no luck. Cheers
5
votes
6answers
1k views

How can I find the total number of TCP connections for a given port and period of time by IP?

On a Linux system there are plenty of methods for listing the current TCP connections for a given port by connecting IP but: how can I count the total number of connections to a port per source IP for ...
0
votes
1answer
33 views

What is the maximum number of characters in a service name?

In TCP/IP, a service name (like http or smtp) is an alias name for the port number. What is the maximum number of characters that can be used in a service name?
4
votes
2answers
2k views

VMXNET3 performance on Linux on ESX 5.0

What kind of performance can I expect from VMXNET3 adapter when running two Linux guests on the same VMware ESX private network defined between those guests? I use VMXNET3 adapter for communicating ...
1
vote
0answers
112 views

TCP load balance authentication

Impala is a piece of Cloudera software which implements an ODBC driver on a desktop, which then connects directly to a Hadoop cluster. In our implementation, our Hadoop cluster sits behind a DMZ, in ...
0
votes
2answers
509 views

How to drop bogus tcp packets through iptables?

We are seeing the issue described here - http://archives.neohapsis.com/archives/bugtraq/2002-10/0266.html In brief, we need to drop bogus packets, such as with SYN+FIN flags set. I can drop this ...
0
votes
1answer
369 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 ...
0
votes
1answer
199 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. ...
5
votes
1answer
155 views

Odd TCP termination sequence

While troubleshooting another thing, I've noticed an odd pattern of TCP closes. Packets: http://www.cloudshark.org/captures/7590ec4e6bef What's happening is that the last few packets of the close ...
1
vote
1answer
182 views

TCP and retransmission [closed]

I'm trying to understand how the transmission and ACK work in TCP. In this Figuure, when A retransmitt the seq 100 after he recive three duplikated ACK , B will answer with 121 ACK or 158 ACK ?
0
votes
1answer
134 views

Linux unfriendly IIS/ASP.NET :-) : Quick download on windows but slow on linux [closed]

This particular web site (gops.tay.be) serves objects quick if I try to request the page using windows, but I get them very slow if trying using linux. There is no difference if I use browser or curl: ...
2
votes
1answer
4k views

Why would a client send a RST packet as reply to a SYN,ACK?

I have a HTTP webservice where sometimes the connection setup fails in a strange way: client sends a SYN packet server sends a SYN,ACK reply client responds with RST In which situations could a ...
2
votes
1answer
232 views

Find number of TCP bytes transmitted

I have rhel4 and rhel6 hosts. I can use netstat -s to see information on the number of segments sent/received. I can use ifconfig to see the number of bytes sent/received on a given interface (for ...
1
vote
0answers
149 views

What could be the cause for outbound TCP/IP traffic beeing blocked while ICMP is still working?

On a Windows Server 2003 there is a strange issue. Every 6 hours the server don't accept outbound TCP/IP traffic while inbound traffic working fine. If the problem occurs I can connect with RDP to ...
0
votes
1answer
152 views

How do I know that my TCP connection is safe from the Firewalls/NAT?

Being on the Azure cloud, I found that the firewalls there drop connections between the Web server and the database quite often. Mostly when there was some inactivity, I think something between 5 and ...
3
votes
1answer
2k views

Reverse proxy for mixed tcp, udp, and http services

I'm building an architecture that will be hosting various services which individually maybe listening on a variable number of ports that could be mixed protocols. I want to map these services to ...
0
votes
1answer
3k views

HTTP 502 Bad Gateway error response

I'm debugging an issue and running out of ideas. I have a server with SharePoint code hosted at port 8080 and a WCF REST service at port 8801. From another machine on the domain, I can connect to the ...
1
vote
1answer
526 views

TCP Duplicate Acks are received

We are trying to get to maximum throughput on ftp over an LTE link. When we are downloading a file using ftp some duplicate ACKs are seen. Reading about the duplicate ACKs, I gather they are sent so ...
1
vote
1answer
2k views

Dropped ACK FIN, ACK RST, RST packets on webserver with iptables

I run a webserver (Apache) on a Debian 7 machine, with iptables on the same machine. iptables rules are generated by the ConfigServer Firewall (CSF) script. The websites hosted there are fine on my ...
-1
votes
2answers
84 views

Is recipient's MAC address necessary for TCP connections across the internet? [closed]

I want to estabilish TCP connection over the internet between 2 computers which are in different local networks (the local networks use wifi). I have looked for description of TCP protocol, ...
0
votes
1answer
1k views

How to find source of TCP failed connection attempts? [closed]

I've got a host that has experienced a sudden increase in the rate of failed TCP connections. It's gone from something like 0.3/sec to 1.5/sec. Regardless of the severity of my particular issue, ...
0
votes
0answers
128 views

Tomcat fails to return syn requests to F5

I have an F5 LTM sitting in front of two tomcat servers which host 4 applications. When I initially create the pools and add the members to the LTM I can hit all applications. This is the weird part, ...
0
votes
1answer
590 views

rmem_max more than rmem_default

I just installed centos 6.3 freshly and noticed the following: [root@localhost user1]# cat /etc/redhat-release CentOS release 6.3 (Final) [root@localhost user1]# [root@localhost user1]# cat ...
0
votes
3answers
107 views

How many packets will it take to send particular data?

If I know the maximum packet size is 1500 bytes say for Ethernet frame v2 then for example I want to transfer 1 KB over the Internet which is roughly 1024 bytes. Will the packet be split into many ...
0
votes
1answer
137 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 ...
1
vote
1answer
1k views

Is it fine to turn off tcp window scaling and tcp timestamps on server?

Our application is running on Amazon server and we were continuously facing the issue related to tcp handshaking. Sometimes we were not able to connect to our application or telnet on port 80 of our ...
0
votes
2answers
283 views

MySQL connection errors when client server bandwidth is exhausted

I have several servers with a lot of outgoing traffic using nginx. When the bandwidth is exhausted (1Gbit), I have problems connecting to my mysql server from those servers. The connect always fails ...
1
vote
2answers
157 views

Network In greater than Network Out?

Stat Image: http://carzz.co/network.png Running a small image website on EC2 without much traffic to speak of (800 user sessions per day). In looking at the EC2 Monitoring on the newly created ...
3
votes
1answer
192 views

How does a file get sent over an HTTP connection? [closed]

A teacher of mine says when you are browsing a web server such as apache2 that has file/directory listing enabled then it secretly opens an ftp server to transfer the file. This confuses me, though ...
2
votes
1answer
294 views

Simulate tcp disconnect using socat

I am trying to use socat command to simulate a tcp disconnect between my client service and EMS broker process on a remote host. I am running this socat command socat TCP-LISTEN:8123,fork ...
4
votes
2answers
169 views

Optimizing OS for HTTP requests

We make a lot of HTTP requests. Recently, we've started thinking about optimizations at the OS level to make more requests from a single machine. In order to check the performance of our OS, I've ...
3
votes
2answers
303 views

once in a while windows / .net application ignores the tcp fin flag

i've run into a network problem which i cannot solve. on a few computers running windows 8.1 and communicating with linux http server tcp connections dangle on the windows side instead of being ...
0
votes
2answers
328 views

VMWare NAT releasing SYN packets from guest but not admitting SYN/ACK packets to guest

VMWare Server 2.0.2 Host OS is Windows Server 2008 R2 Standard Guest OS is Windows XP I am using VMWare VMNet8, the NAT network. The VM guests can't see out to the network around the VM host. Packet ...
1
vote
0answers
177 views

How can i detect and diagnose local network problems on a multi-server environment?

I'm a software engineer who trying to detect (and solve if possible) weird local networking problems since 2 weeks on multi-server hosting environment. We bought 3 dedicated boxes with 32GB ram 8 ...
2
votes
1answer
118 views

How do you change tcp_congestion_control on OpenVZ?

I have a network of OpenVZ machines that I am testing various congestion control methods on. I need to know how to change the congestion control. Currently I get nothing but permission denied. Is it ...
-1
votes
1answer
773 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
vote
1answer
62 views

routed network, subnetwork clients has broken tcp connection

I manage a linux server which works also as a router, and route between following networks: PPPoE (to connect to ISP) (default gw) wired network 2x VPN networks (PPTP and openVPN) wireless AP (DHCP) ...
0
votes
1answer
61 views

Routing between two PC

I have two computers connected by wire directly: PC-1 ============= PC-2 PC-1 configuration: IP Address: 192.168.1.1 netmask: 255.255.255.0 PC-2 configuration: IP Address: 192.168.1.2 ...
0
votes
1answer
242 views

Oracle 11g TNSLSNR LAST_ACK connection flooding

We have Windows 2k3 EE SP2 with Oracle 11.2.0.1.0 DB installed. The DB is used by different applications (including web-apps and services). From time to time, we have some problems with the web ...
0
votes
2answers
2k views

TCP port numbers reused and TCP Retransmission

Facing issues due to TCP Port Reuse and Retransmission for HTTP traffic. My deployment is as follows: enter image description here I have a squid proxy installed on a unix machine which is sending ...
0
votes
1answer
101 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 ...
3
votes
1answer
681 views

Troubleshoot Broken TCP From OpenVPN Client To Server; But ping, traceroute Work

I'm troubleshooting an OpenVPN Server setup on OS X Mavericks. Prior to the 10.9 upgrade, this all worked, and I'm trying to isolate the problem to something fundamental or my server/client setup. ...
2
votes
1answer
8k views

Root cause of “curl: (56) SSL read: errno -5961” errors

I was evaluating some SSL failures, and noticed that when I use curl to one of the failing sites, I got curl: (56) SSL read: errno -5961; however, my google queries for that error didn't show the ...
0
votes
0answers
278 views

How to forward UDP and TCP traffic from one IP to another

I have a server with two LAN cards installed. I have one server in U.S and one in India. I have created a GRE tunnel to route all traffic from the U.S Server to my Indian Server. My traffic has ...
0
votes
1answer
196 views

Several Server Errors (No database connect, can't create TCP/IP socket etc

My server stops taking requests on my website today. It works for some time, but then the server just stops working and throws several errors: 500 Internal Server Error Warning: mysql_connect(): ...
2
votes
1answer
310 views

How to configure tcp wrapper

I have a server with ip-address 192.168.0.1 and a client with ip-address 192.168.0.2 both of them are able to connect with each other. Now the problem is I have configured TCP Wrapper on my server ...
1
vote
1answer
157 views

Prevent Linux from processing incoming ICMP Host unreachable packets

I have a test setup with one host on a network (10.1.0.0/16) talking via TCP to another one on another network (10.2.0.0/16) and a gateway in the middle. Sometimes, the TCP connection is lost and ...
0
votes
1answer
721 views

Random TCP Resets

We got randomly TCP "reset" error when we send request to remote server. Log from remote server Cisco TCP Connection Terminated,Nov 05 14:43:39 EST: %ASA-session-6-302014: Teardown TCP connection ...
2
votes
1answer
60 views

Request to server x Reply from server y

I need some advice from you guys: I'm dealing with a custom loadbalancer/software for which we will use 2 main servers and about 8 slave servers. In short: User sends request to main server, main ...
1
vote
2answers
380 views

Using proxy server to redirect MySQL traffic to multiple servers using standard port?

Is it possible to redirect MySQL (tcp) traffic to multiple servers based on domain name alone? Our DNS is setup to point several sub-domain aliases to one proxy machine. (running haproxy and ...