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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TCP - TAP performance

Linux. Is there a performance loss from using a tap device vs a hardware one like eth0 ? The goal is to create a user space tcp/ip stack and avoid the kernel as much as possible. I would like to be ...
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2answers
53 views

Implementing TCP Sticky Sessions With HAProxy to Handle SSL Pass-through Traffic

How can we implement session stickiness in HAProxy when SSL must terminate on the backend servers? We need the stickiness because backends cannot share sessions. This is my original configuration: # ...
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1answer
28 views

Proxy-attack simulation

I have a WS2008 x64 server, that has NodeJS application working on its 80 port. Server constantly receives queries from different IP-addresses that are trying to use my application as a proxy. NodeJS ...
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46 views

Cannot make TCP Connection with OpenVPN Server

Client OpenVPN assigned IP: 10.8.0.2 ↓ TCP on 1194 Internet ↓ Router port-forwards 1194 to server- Public IP 104.162.67.198 ↓ Server LAN IP: 10.8.0.1 I think the above is what I am trying ...
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0answers
30 views

Route 53 TCP Health Monitoring with NC

We have multiple servers which are running UBUNTU 12.04 OS. We would like to create health monitoring for all of the servers. Since none of the servers are running web server I would like to create ...
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0answers
43 views

WSAECONNREFUSED SAP Gui unable to connect on SAP server on hp ux - inetd.conf file reference

I have a sap server installed on HP-UX vm, up and running. when I try to connect to the server from SAP client GUI installed on windows machine I get the following error --------------------------- ...
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2answers
235 views

How is a TCP request routed from a virtual machine to an outside resource and back again?

Scenario: Computer A has a local ip of 192.168.1.100, which is running a VM inside of it. The VM now makes a tcp request to an external IP address (74.125.225.98). Could someone explain how the ...
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0answers
16 views

delay in ACK packets for ldap abandon request

we have migrated from an openldap server on linux to a DirX on windows 2008. The ldap server und normal serch request behaves as expected. However with some applications (weblogic deployed webapps) ...
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1answer
61 views

Is ARP Connection oriented or connectionless?

Is ARP Connection oriented or connectionless? It uses TCP, but does that consider it connection oriented?
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2answers
29 views

Display IP & TCP statistics per interface (netstat -s with interface)

Linux has the ability to display protocol statistics with netstat -s. The output looks something like: Excerpt: 7487 times unabled to send RST due to no memory TCPDSACKIgnoredOld: 817 ...
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1answer
76 views

Limit Number of TCP connections in Linux Server, to avoid attack

I want to limit the number of TCP connections in Linux server, I have used the following command. iptables -A INPUT -p tcp --syn --dport 80 -m connlimit --connlimit-above 25 --connlimit-mask 32 ...
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1answer
52 views

What is the best way to measure latency via a “telnet to port” test, preferably with built-in Linux tools?

I'm writing a Graphite/Diamond collector measuring network latency. Specifically it should measure the time it takes to open up a connection to a port on a remote server. And it needs to work via ...
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0answers
15 views

windows firewall , some ports not listening

I've added an inbound connection rule for my windows 8 firewall on windows server 2012: I've restarted the Windows Firewall. When I check that port using this program, it says that it is not ...
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1answer
47 views

Tuning Linux TCP for large number of TIME_WAIT

It looks like we have a bunch of tcp connections hanging around on a busy webserver, this is the output from ss -s: Total: 366 (kernel 1037) TCP: 72108 (estab 130, closed 71964, orphaned 0, synrecv ...
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1answer
16 views

Solaris 11 / OpenSolaris - stop processes from listening?

I would like to write a script to secure Solaris 11 servers in preparation for internet access. In addition to enabling ipfilter, I would like to disable network-accessible services that are not ...
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0answers
18 views

Dropped TCP Packets over two-stage IKEv2 VPNs

Something of a weird setup this: There are two Virtual Private Clouds (10.100.240.0/20 = prod1 and 10.101.0.0/24 = control), which have a valid router between them. Control hosts a VPN that is meant ...
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0answers
19 views

iptables NATed traffic is not getting ack back

Ok, I'm trying to setup the classic iptables DNAT/SNAT scenario (RHEL 6.5, 2.6.32-431.17.1.el6.ppc64 kernel ): *Host A 172.16.0.0/24 nets Host B 172.16.0.0/24 + 192.168.0.0/24 nets Host C ...
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5answers
69 views

Get number of TCP established connections

On a Linux server one can use netstat -tan | grep ESTABLISHED| wc -l but this will not work on a high load server with watch -n1. Such approach works fine if the server is not very busy or the ...
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0answers
19 views

Random connection reset?

I'm using an Apache server on CentOS 5, and frequently, on the first try to connect to the website, it will give a "Connection was Reset" screen. But after refreshing it, the page will load as fast as ...
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1answer
66 views

NTttcp shows slower throughput on loopback (127.0.0.1) than on network

I am using NTttcp to find a baseline for what throughput I can expect between a client and server on windows. When I ran the client and server on two different machines on our LAN I got the following ...
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0answers
27 views

apache 2.2 vs 2.4 TIME_WAIT issue

I'm using apache + tomcat through mod_prody_ajp on windows server - simplest configuration without any tunings. Apache 2.2 could reuse TCP connections when forwarding request to tomcat. Apache 2.4 ...
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1answer
41 views

TCP Load balancing

I need to implement an architecture that can serve 3 million GPS Devices sending Location Updates/Alerts (every 10 secs) to our system for processing. Features: 1) TCP communication. 1) Long lived ...
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2answers
820 views

TCP Dump, cannot understand these 4 lines?

I need support understanding these 4 lines. looks like tcp dump but im actully not understanding what exactly is happening here. 13:13:22.407445 IP 192.168.246.128.54955 > 192.168.246.13.80: S ...
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1answer
60 views

How does an IP address goes down from an Application Layer to IP Layer? [closed]

Using the classical TCP/IP layers model, I am thinking about an application (for example a browser) acting as a client wanting to talk with a server (e.g. a web server). Of course it has to use the ...
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1answer
93 views

TCP piggybacking introduced by a man-in-the-middle network node beween the client and server?

When wireshark trace taken on the client side it appears to be: ---SYN---> <-SYN-ACK- ---ACK---> -HTTPGET-> But when wireshark trace taken for the same traffic on the server side it ...
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4answers
206 views

Is there a netstat -s equivalent for windows?

I know that netstat -s exists on Windows, but it displays way less informations than on Linux/OS X. It only gives 8 counters about TCP, while on Linux it's more than 50. I'm looking for any ...
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0answers
87 views

TCP Window Scaling Problem over MPLS

After extensive troubleshooting why the TCP speed over an MPLS circuit is slow in one direction, I figured out that by adjusting the TCP window size the situation improved a lot. Maybe you can tell me ...
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0answers
52 views

TCP congestion collapse

I am experiencing suboptimal performance on an EC2 instance connecting to an RDS instance. This particular instance was built before VPC's existed, so all the traffic is flowing through a single ...
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2answers
86 views

Proxying TCP by hostname

I've got multiple game servers TCP ports on my single host machine. The goal is to have users be able to connect to server1.domain.net and have their directed based on that subdomain. My first ...
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0answers
55 views

TCP ignores some packets for no reason

I have a weird problem which I can't understand. The actual network configuration is quite complex, because I am using Openstack and Docker to build a virtual network. However, the problem is not ...
3
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0answers
103 views

TCP connection stuck in SYN_RECV state despite ACK received

My client and server are both internal machines. tcpdump on both client and server show all three parts of handshake are communicated, however netstat on server shows SYN_RECV, and on client shows ...
32
votes
1answer
903 views

Random TCP RST's on certain websites, what's going on?

Short version: One Windows Server 2012 machine on my network is getting persistent but intermittent TCP RSTs when connecting to certain websites. Dunno where they're coming from. Check out the ...
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2answers
100 views

Recommended TCP keepalive settings for a busy server

We are having some network timeout issues on a Debian server that is quite busy, and maintains multiple connections to a number of other servers on the network. Here are our current TCP keepalive ...
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0answers
19 views

Clients phone provider claiming high latency over UDP, how do I test?

A client of our uses a hosted phone solution for his 50 agent call centre. They use a hosted dialer who make the out going calls, once the connection is made the call is passed to my clients user ...
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0answers
31 views

Windows Server 2008 consuming a lot of bandwidth

My Windows Server 2008 has been consuming A LOT of bandwidth in the last days (990 GB). This is a development server so it should not consume more than 100mb aprox. We noticed this after the server ...
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2answers
49 views

Can't block spammy IP

I'm being attacked by 37.59.4.76. It's sending me a great amount of data, which is destroying my dataplan. I've added the iptables Chain num pkts bytes target prot opt in out ...
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2answers
54 views

TCP/UDP Small Package Size optimization [closed]

I currently have the problem, that when a LOT of RTP streams (>800) go to one server the max. speed is onlynabout 70-80 Mbit (on a Gigabit LAN - all Hardware components are Gigabit components) 130 ...
5
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0answers
104 views

POST of MTU + ~798 bytes gets lost

I have a very weird issue with certain packets not arriving on the destination host. It happens when we transmit a POST that is somewhat larger than the MTU. We can reproduce it with this script: ...
2
votes
1answer
65 views

Relationship between tcp state TIME_WAIT & HTTP keep-alive

What is the relationship between keep-alive on a HTTP request and a tcp socket in TIME_WAIT - should they be correlated? Furthermore, should system and web server settings be aligned e.g. ...
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0answers
19 views

Source ip based Anycast-BGP?

I'm just getting interested in networking so don't be too harsh on me :) Ideal: 2 servers with shared ip; ip X Client 1 pings ip X > always server A Client 2 pings ip X > always server B ...
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1answer
32 views

Geo distributed ip [duplicate]

When i ping 8.8.8.8 from my home computer (europe) i get around 26 ms latency. When i ping 8.8.8.8 from a server(US) i get around 1 ms latency. When i ping my (US) server from home (europe) i have 130 ...
0
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0answers
54 views

HAProxy RTMP (TCP) load balancing

I am using HAProxy as load balancer for the RTMP protocol. For now it's working very very good but I have one small problem. I want to send the client's IP on the RTMP request after the load balancer. ...
0
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1answer
118 views

How to trace dropped TCP connections?

Trying to help someone with a situation where TCP connections get mysteriously dropped after a few minutes for no apparent reason (this happens even with non idle connections). Both client and server ...
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0answers
28 views

apache bench handshake failure server sending TCP FIN

I am trying to verify handshake performance by sending number of requests with out setting concurrency with below command. ab -k -n 18750 -c 1 -Z AES128-SHA -f TLS1.3 ...
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4answers
162 views

Cannot work out what is using port 8080

In Windows Server 2003 R2 64 Bit SP2 I have an app which will only use port 8080 but something is already using it. I would be happy to just kill whatever is using it but I can't work out what it is. ...
0
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1answer
79 views

Existing TCP Relay Solutions [closed]

I have a scenario which requires the use of a TCP Relay. Before I set out to write something custom, I wanted to see if anyone knows of existing software that can do this for me. I have 2 devices on ...
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1answer
37 views

TCP ports duplication [closed]

I need to communicate server1 to server2. Server1 should have to fetch some records from Server2 when we execute program.exe will make server1 to fetch server2 When I gave netstat -an | find ...
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2answers
104 views

Wireshark “length” column - what does it include?

Can anyone tell me what the "Length" column in WireShark refers to? I'm pretty sure it's the "size" of the entire frame on the wire. I did some calculations, but I didn't get the number that ...
1
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1answer
254 views

HTTP not finishing over LAN. Hardware cause?

On a customer server running Apache 2.2 on Windows server 2012 we're noticing that from time to time, some requests to the server never finish. Using wireshark I've found a bunch of duplicate ACKs get ...
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0answers
44 views

Cannot connect to TCP service from remote host

I have two servers running RHEL 5.8. SRV1 (10.58.192.36) has a service running on port 9002 and I need to connect to this service from SRV2 (10.58.192.42). [root@SRV1 ~]# netstat -anp | grep 9002 tcp ...