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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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, ...
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3answers
68 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 ...
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3answers
4k views

Why is UDP slower than TCP on Ubuntu Server?

I transfer data between two Ubuntu Servers (12.04) via iperf on 1Gb LAN. iperf -s <-> iperf -c <addr> -n2G TCP speed = 925 Mbits/sec iperf -su <-> iperf ...
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2answers
368 views

Clustering TCP servers, so can send data to all clients

I'm developing a real-time mobile app by setting up a TCP connection between the app and server backend. Each user can send messages to all other users. (I'm making the TCP server in Python with ...
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1answer
107 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 ...
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1answer
43 views

Off-loading HTTP traffic

Need help in off loading HTTP traffic. My web server is having a lot of traffic resulting in slow response. It is also getting requests on port 80 from various mobile applications too. Traffic from ...
3
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1answer
355 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. ...
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2answers
95 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 ...
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2answers
146 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 ...
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1answer
3k 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 ...
3
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1answer
184 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 ...
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1answer
143 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 ...
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1answer
121 views

TCP 443 Connection goes into server but never reaches Apache2 (Passenger)

We have some weird problems, when external servers try to connect to our Website on Port 443(TCP) which is an Apache2+Passenger and a Rails Application. The problem only happens rarely. I started to ...
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2answers
189 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 ...
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1answer
326 views

problems simulating TCP SYN flood

I'm trying to simulate a TCP SYN flood to tune a web server (planning to deploy on AWS). I setup a 'target' VM, disabled iptables and running hping (hping -p 80 -i u1000 -c 1000 -S destaddr) from ...
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1answer
153 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 ...
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2answers
180 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 ...
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3answers
4k views

Tuning iSCSI storage

This is a Canonical Question about iSCSI we can use as a reference. iSCSI is a protocol that puts SCSI commands as payload into TCP network packets. As such, it is subject to a different set of ...
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1answer
2k views

tcpdump capturing tcp resets by host

I am trying to figure out where my tcp resets on my webserver happen. I have the following capture: tcpdump -fnni bond0:-nnvvS -w dump.pcap 'tcp[tcpflags] & (tcp-rst) !=0' When I look at the ...
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2answers
164 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 ...
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1answer
85 views

TCP syn cookie calculation on Windows Server

Windows Server uses uses TCP syn cookies to protect itself from syn-flooding attacks. Is it known, how the operating system (Windows Server 2008 R2 and Windows Server 2012) calculates the syn cookie? ...
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1answer
440 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 ...
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2answers
192 views

Server 2012: SYN, no ACKs, on TCP ports higher than 6000

Seems ridiculous to read it back out loud, but I'm at a loss here. Server 2012 Standard. Runs a daemon for an accounting package on TCP 12502; at some point, the server stopped accepting connections ...
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0answers
119 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 ...
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1answer
86 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 ...
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1answer
2k views

TCP: Treason uncloaked! shrinks window Repaired

I have this error. The server works fine but sendmail doesn't. I can't reach it for download emails but it sends them. I have this when I type dmesg: TCP: Treason uncloaked! Peer ...
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4answers
21k views

How do I make cURL use keepalive from the command line?

I'm trying to verify that HTTP persistent connections are being used during communication with a Tomcat webserver I've got running. Currently, I can retrieve a resource on my server from a browser ...
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6answers
14k views

Why would a server not send a SYN/ACK packet in response to a SYN packet

Lately, we've become aware of a TCP connection issue that is mostly limited to mac and Linux users who browse our websites. From the user perspective, it presents itself as a really long connection ...
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1answer
53 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) ...
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1answer
57 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 ...
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1answer
49 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 ...
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1answer
103 views

Is there a Windows utility to create a TCP server to server link?

I two systems that I need to connect, but both act as servers. The first is a scale controller that does not have the ability to open a connection before sending a weight. It will send weights if a ...
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153 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 ...
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1answer
114 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
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1answer
138 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 ...
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1answer
237 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 ...
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1answer
105 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 ...
4
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1answer
152 views

HaProxy for game servers, what's wrong with my configuration?

I host a website with a game client that uses TCP for connections. I am currently looking for a way to proxy my connections from one server to my origin server. I have tested Iptables forwarding and I ...
2
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1answer
55 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 ...
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2answers
218 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 ...
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1answer
227 views

TCP DOS: How to terminate CLOSE_WAIT connections? [closed]

One of my servers is getting DOS'ed - there are a large number of connections in the CLOSE_WAIT state which are preventing legitimate users from connecting to the system. So is there any way to close ...
2
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0answers
208 views

Should I set rto_min for a route inside data center?

We have a few dedicated server rented in a data center with debian 7, kernel 3.2. We use one of those servers as a database server. The network between our application server and database server is ...
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6answers
566 views

Is it possible to redirect/bounce TCP traffic to an external destination, based on rules?

I'm not even sure if this is possible... Also, please forgive my ignorance on the subject. What I'm looking for is for "something" that would allow me to redirect all TCP traffic arriving to host A ...
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0answers
400 views

How to stop NAT dropping idle connections?

I have a TCP connection that can be idle for many hours. The traffic is flowing from the server to the client only. One might say it's kind of push notification. My home router, however, tends to ...
2
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0answers
86 views

Change TCP wait for ACK timeouts in Win7/WinServer

Is there any possibility to change default wait for ACK timeout in TCP network on Windows 7 or Windows Server ? I'm using very slow network ( 1200 bps ) and want to tweak TCP. When using default ...
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1answer
412 views

How do routers combine WAN and LAN traffic (packet data over wifi and ethernet)? [closed]

In my office, we have a leased line connection which is shared by some 20 users over wi-fi. This causes congestion on the router's end, resulting in slow speed due to high packet drops (and consequent ...
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90 views

How to get more NFS packet details from Wireshark?

How can I get Wireshark to give me details about NFS packets at this level of granularity? (as exemplified here here) Specifically, I am interesting in looking at the the "Stable" option toward ...
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1answer
2k views

How do i route TCP connections via TOR? [closed]

I was reading about torchat which is essentially an anonymous chat program. It sounded cool so i wanted to experiment with making my own. First i wrote a test to grab a webpage using Http. Sicne .NET ...
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4answers
613 views

Can I find out what certificate revocation server an application is contacting?

I'm trying to install an application on a machine running Windows XP Pro. There are two different servers being contacted, both using the same wildcard certificate (GoDaddy). One via https, one ...
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1answer
185 views

SSL Connect timing out during handshake (client exchange re-transmission)

We have a Java LDAP client making SSL connection to AD. Some times the connect hangs with client and server re-transmitting Client Key Exchange and ACK packets continuously as shown below and ...