TCP and IP are two important protocols used in networking today. Due to their importance, the Internet Protocol Suite is also commonly known as "TCP/IP"

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Connection Timeout Issues - Solaris 11 SPARC

We're currently running some performance tests using Solaris 11 (SPARC) on some large hardware. The tests, which consist of sending SOAP requests (50kb per request), are running well up until we get ...
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64 views

What is [PSH, ACK] doing during my connection to a global catalog server?

A linux server of mine is trying to establish a LDAPS connection to a global catalog server and the connection is getting dropped (presumably by the GC side). For the purpose of discussion, let's ...
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1answer
110 views

Port forward remote desktop without a gateway over 3G modem router [closed]

I'm trying to connect from a laptop, through a VPN, and a 3G modem/router, to a remote PC / computer. PC (192.168.1.33) | 3G Modem (192.168.1.22) | [3G internet, connecting to VPN] | ...
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38 views

Incoming tcp SYNs possibilities

This might be a general TCP question. Can I receive TCP SYN packet on an established connection OR a connection in TIME_WAIT state? Is is possible?
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2answers
504 views

When a server IP changes, do exising TCP (e.g. http/mysql) connections remain running

We have some PHP-FPM servers and when they need a database connection, they connect to an HAProxy server which selects them a database server to use and the connection opens. When we then want to ...
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1answer
55 views

How to compare 2 TCP/IP stacks or implementations? [closed]

I have to recycle an old machine into a networking node for managing TCP/IP connections and PPP protocols ( basically a DSL connection ); I'm not asking for something more than this, all the tasks ...
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104 views

Windows Server 2008 Enterprise - Print Server Role - TCP/IP Print Server Service Won't Start

I have a few Windows Server 2008 Enterprise edition Servers running Printer Server Roles. On these servers there are two system services: Print Spooler and TCP/IP Print Server (LPDSVC). The TCP/IP ...
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1answer
131 views

Host doesn't send ACK-SYN packets for transparent proxy

I am setting up a transparent proxy using haproxy, the setup works without the 'source 0.0.0.0 usesrc client' line. When I add that line in, the endpoint is called from the original client's ip ...
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96 views

Lots of packets pruned from receive queue because of socket buffer overrun - reason to worry?

I know this question has been asked before, but maybe not in this particular context: I have a setup with a couple of MS2008R2 HyperVisor servers running a number of Ubuntu guests. Our webproxy runs ...
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1answer
57 views

What is the incentive to operate a TCP/IP node? [closed]

I mean, why does anybody relay messages to other nodes? Why are these eleven good people below helping me send my bytes to their destination? traceroute to stackoverflow.com (198.252.206.140), ...
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2answers
298 views

Can you use WMI to determine if a connection gets its DNS servers from DHCP?

The DNS server search order for a network interface can be read from Win32_NetworkAdapterConfiguration like this in Powershell, or programmatically using .Net ManagementObjects: > $NICs = ...
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36 views

Printer lpd daemon refuses print job if a command's new-line sent separately — bug?

I'm encountering some printer LPD daemons which work fine if the new-line is sent in the same packet as the command, but break if the new-line is sent in a separate packet. Is that a bug in these ...
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1answer
70 views

TCP client and server work for X times but hang after that

I'm a software engineer, but I think my problem needs a network engineer... For the software side of things, have a look at my Stack Overflow question: ...
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2answers
365 views

List of TCP & UDP ports known to be used by malware, etc [closed]

Where can I find a regularly updated, downloadable list of TCP & UDP ports that are known to be commonly used by malware, trojans, etc.? This is for import into an IT asset management system to ...
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1answer
40 views

Firewall Connections fail to open under load

Problem : During High load , our applications are encountering errors : java.net.connection Time out. After some investigation , we found out that it was Firewall the root cause, but still don't know ...
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1answer
77 views

Could the IPG parameter in Robocopy cause TCP/IP packet problems if it is too high?

I need to throttle a robocopy transfer to limit bandwidth usage. It is already set to 1500 (/IPG:1500). I would like to increase this IPG to around 2000 (or more) in order to lower even more the ...
3
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2answers
181 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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1answer
2k views

What else does “netsh int ip reset” do?

According to this KB article when you run the "netsh int ip reset" command, all it does is to reset the content of two registry keys: SYSTEM\CurrentControlSet\Services\Tcpip\Parameters\ ...
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1answer
164 views

ping -a sometimes returns host name and sometimes returns FQDN. Why? Does this mean DNS is corrupt somehow?

I have a Windows machine called abcd for example and it uses DHCP to receive an IP address (172.28.45.5 for example) When I perform ping -a 172.28.45.5 sometimes I receive abcd as the hostname. ...
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95 views

Drop in HAproxy traffic with increase in connections

We have an intermittent issue that involves a severe drop in network traffic (both IN and OUT) on our HAProxy load balancer. It happens a couple times a day. HAProxy is configured to limit requests ...
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1answer
1k views

Diagnosing packet loss / high latency in Ubuntu

We have a Linux box (Ubuntu 12.04) running Nginx (1.5.2), which acts as a reverse proxy/load balancer to some Tornado and Apache hosts. The upstream servers are physically and logically close (same ...
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1answer
149 views

Server with two default gateways won't listen on the second gateway

I am testing a redundant internet connection setup that works like this - I have a network segment, 192.168.80.X It has two gateways - 192.168.80.1 - a FW connected to a frame relay line ...
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2answers
3k views

ESXi network setup for isolated internal virtual machines

Using ESXi v5.1 and vSphere, my networking is setup like so: One standard Switch: vSwitch0 vSwitch0 has one uplink physical adapter (Internet connected) vSwitch0 VM Network has 3 virtual machines ...
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1answer
324 views

Where to find WINS IP address in registry?

I have been writting a powershell script to remotely dump the TCPIP information from the registry of machines in my Windows Domain. I was able to dump the default gateway, subnet mask, DHCP server ...
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1answer
84 views

Need help routing Cisco network- IP routing [closed]

In the above network, can you help me configure routes so the computers on the left can see the computers on the right, and vice versa? I know the syntax of the command is ip route {network ...
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181 views

SSH attempt keeps failing, syn+ack does not reach machine

1 0.000000 10.0.0.1 10.1.1.0 TCP 66 49285 > ssh [SYN] Seq=0 Win=8192 Len=0 MSS=1260 WS=256 SACK_PERM=1 2 0.001160 10.1.1.0 10.0.0.1 TCP 66 ssh > 49285 [SYN, ACK] Seq=0 ...
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1answer
148 views

Do keepalives to socket connections exist?

Pre briefing: Although my question is broad on purpose, I am dealing with nginx connecting to php-fpm (fcgi), which is served via a local socket (/tmp/somesocket.socket). Nginx has a setting to ...
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1answer
235 views

is it possible to use ms loop back adapter to setup local vlan

Is it possible to use Microsoft Loop back adapter to set up Lan connection between two computer which is logically isolated from the main network? 1st computer: has a regular ip stack 192.168.1.x ...
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2answers
663 views

How to globally limit total number of TCP connections with iptables?

I'm having quite a difficult time figuring out how to REJECT both inbound and outbound connections from a machine with iptables once the total number of TCP connections hits a global maximum without ...
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54 views

Suspecting Wrong Configuration of Sysctl (Silent TCP Drops?)

I have a high load long TCP connections server and I had to tweak sysctl to make sure I get no errors, At the moment I get no errors, But I think i might get TCP drops without errors. Here is sysctl ...
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1answer
94 views

Is their an official tool to tweak Windows 2008 server TCP configurations?

We are running scripts that initiates numerous TCP connections and disconnects right away. It's just to test if the remote report is opened and responsive. But we are having random strange issues ...
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1answer
134 views

Enabling TCP/IPv4 through Windows PE

From RDP, i've disabled the TCP/IPv4 protocol by mistake and now, obviously, i can't use rdp anymore to re-enable it. Is there a way to enable it again from Windows PE?(OVH rescue pro)
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1answer
58 views

Random three minute delay for database server connect

we use InterBase on a Windows 2003 server, and in random intervals the client connection to the server takes 180 seconds (three minute) longer than usual. The application does not "hang" with the ...
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49 views

Linux + OpenVPN + SNAT + Failure on client grab the reply to it's own generated traffic

Ok, I'm really desesperate I need to release an openvpn deploy to get rid of a dying server. On the subject: I installed OpenVPN with a routed interface (tun0) into a server with a public IP + 3 ...
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1answer
221 views

Frequent interruptions of SSH connection to VPS

My SSH sessions die at what seem like random times - response will stop, and then a few seconds later PuTTY will pop up a message with, "Server unexpectedly closed network connection." It seems to ...
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2answers
238 views

what is meant by application layer protocols being encapsulated into transport layer protocols? [closed]

I am reading this wikipedia article: http://en.wikipedia.org/wiki/TCP/IP_model#Application_layer It talks about how TCP and UDP are transport layer protocols which are designed to connect one host ...
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2answers
3k views

Slow data transfer between Server 2012 and Windows XP/7 Clients

I've installed a new Dell PowerEdge R720 server at a small company which eight workstations. It is running Windows Server 2012 Standard. I've then installed Hyper-V (role) onto the server and created ...
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1answer
119 views

TCP works for a while, then fails, why?

This comes from an implementation of OpenStack, and we have a fix, but I don't understand why we need this fix. My machine has an ip of 192.168.20.45 My default gateway (pfsense) has an ip of ...
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1answer
426 views

Determing MSS value on Windows Server

In this Technet article about the MSS limitations of Windows Server 2008, it mentions: After analyzing the network trace collected on the source Windows 2008 Server, we found out that the remote ...
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1answer
463 views

How to debug why WAN TCP/IP throughput is lower than expected?

I'm trying to figure out why tcp/ip throughput between two hosts I control is much lower than expected. Host A: internet connectivity provided by Comcast (Residential) in Boston Metro -- can ...
3
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1answer
150 views

TCP Congestion Window on Windows Server 2003

After reading this blog post by Ben Strong, I started looking on the internet for information on how the Initial Window size could be manipulated on Microsoft Windows Server 2003 (R2, 64bit in case it ...
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1answer
841 views

TCP/IP connection to SQL Express works on HALF of the clients in a WORKGROUP

So far I have learned the following facts about Microsoft SQL Server Express, including version 2012, and earlier versions like 2008R2, and 2008, and for the most part all the way back to SQL Server ...
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3answers
276 views

Max client TCP connections through a router

I've just been thinking about what the maximum number of client connections would be out of my home LAN to a single server on the internet. My home router is also NAT'ing the connections to convert ...
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1answer
67 views

RPC SERVER is unavailable

windows 2003 is getting this error. restart the machine or just the network connection fix the problem. date and time is the same one. tcp/ip is started and running remote registry is running the ...
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100 views

tcp recycle and retransmission

TCP recycle reduces TIME WAIT by reusing sockets. It avoids collision with older packets by storing timestamp and receives packets with greater TCP timestamp. What happens when the client retransmits ...
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2answers
164 views

How does VPN software 'hijack' packets for tunneling?

My current mental model An application interacts with the operating system to produce an OSI model stack-based packet process - subsequent layers of encapsulation Somewhere along the line before the ...
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2answers
114 views

Thousands of port 25 connections

Tonight a few IP addresses made almost 2500 connections on port 25 of a mail server. 2500 is the max limit, and 50 or less simultaneous connections is normal. They did nothing once they made the ...
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1answer
402 views

Long TCP/IP Connect time (20-40s) with Apache 2.4, mod_proxy_ajp, Tomcat 7.0.39 running on Windows Server 2008 R2

The initial connection to an Apache HTTP Server is taking a very long time (20-40s), but the subsequent connection is very fast (<50ms). I use Apache HTTP Server as a load balancer using ...
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2answers
792 views

Linux server resend SYN ACK

I am troubleshooting a connection timeout problem between two Linux boxes, where it seems the ACK to SYN-ACK was lost on the server's stack. The tcpdump is done on the server side. The client got ...
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1answer
117 views

Multi-IP server: how do programs know which IP to use?

I recently tried adding second IP address to our server for various reasons and found that now when I check netstat -anob there are many programs/services listening and establishing connections to ...