0
votes
0answers
22 views

cisco wireless router not allowing full tcp handshake when in router mode

I have a recently-purchased cisco rv220w wireless router. My setup is as follows: Internet -> asa 5505 -> 10.0.1.0 subnet -> wireless router (subnet 10.0.3.0, public facing ip is ...
0
votes
1answer
20 views

TCP Zero windows size and full windows size

The problem that we are facing is that some of the http connection have response time > 60s (about 5%). I discover that the problem should between the web server and loadbalancer. Here is my finding, ...
-3
votes
0answers
21 views

What protocol do these segments use? [on hold]

I'm trying to look at these two segments, and determine what type of protocol each one of these are (no Ethernet headers) The first one: 4500 001d 003a 0000 4011 bc19 c0a8 01ea 0ae4 4081 0400 0201 ...
0
votes
0answers
10 views

Reproduce netperf TCP_RR test with NTttcp

The documentation of NTttcp being hard to find and to understand, how can I mimic the behavior of the TCP_RR netperf test with NTttcp?
0
votes
1answer
74 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.
1
vote
0answers
36 views

Linux MIPS box: ICMP (ping) works, but TCP does not - how to fix it?

I'm trying to set up MIPS Linux box network. Here is it's configuration: ~ # ifconfig eth0 Link encap:Ethernet HWaddr CC:5D:4E:FF:45:7F inet addr:192.168.0.2 Bcast:192.168.0.255 ...
1
vote
1answer
49 views

TCP echo server security [closed]

I am setting up a Linux server similar to a TCP echo server and am wondering about security issues I should be concerned about. This will be a bare bones Centos/KDE server with no additional files ...
-6
votes
1answer
48 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), ...
0
votes
0answers
83 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 ...
1
vote
0answers
46 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
0answers
128 views

XenServer open vSwitch performance downgrade

I'm trying to capture part of an inter hypervisor traffic between 2 virtual machines running over XenServer 6.2. I want to mirror some TCP sessions to a 3rd virtual machine with minimum affect to the ...
0
votes
1answer
80 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 ...
3
votes
1answer
175 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 ...
1
vote
0answers
75 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
60 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 ...
0
votes
1answer
275 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
0answers
70 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
171 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 ...
1
vote
0answers
101 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 ...
2
votes
0answers
51 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 ...
-2
votes
1answer
152 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 ...
1
vote
2answers
121 views

DHCP serving has stopped working

Something happened in our server room over the weekend that had me in the office late Saturday night replacing two switches. After powering down both racks, I have an issue where none of the computers ...
0
votes
0answers
91 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 ...
1
vote
2answers
294 views

NAT Gateway - Maximum connection limit

I know just enough networking to be dangerous. The nitty gritty low level details of NAT are not something I am particularly knowledgeable about. I accidentally found myself in a discussion earlier ...
0
votes
2answers
210 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 ...
6
votes
1answer
2k views

Unexpectedly shrunk window

I run a major media upload/download site and I noticed these: Is this serious or background noise due to the big file sizes and is there any tweaks I can add to /etc/sysctl.conf to improve and ...
2
votes
1answer
80 views

three-way handshake & sequence number

Looking at the image below, taken from the book of Ilya Grigorik - High Performance Browser Networking, I can understand that the SYN packet picks a random sequence number which is incremented in SYN ...
1
vote
1answer
114 views

Reasons for a TCP Timeout scenario

I am actually currently investigating long running connections of a Java/Tomcat based Web application. After ruling out any internal or application based reasons, I am now down to the network layer. ...
21
votes
5answers
1k views

Can TCP and UDP packets be split into pieces?

Can TCP packets arrive to receiver by pieces? For example, if I send 20 bytes using TCP protocol, can I be 100% sure that I will receive exactly 20 bytes at once, not 10 bytes then another 10 bytes ...
3
votes
0answers
114 views

snmp MIB-TCP::tcp not showing any usage

I am trying to configure MRTG on all of my servers for making a network weathermap, this requires running SNMP which MRTG gets the information from. So, I installed it on two servers the exact same ...
0
votes
2answers
193 views

Test a server using MTR through TCP

Is it possible to use MTR over TCP? If not is there an alternative? I have done some research and I am not finding any way to do such a thing, so I'm wondering if anyone has had any experience with ...
-2
votes
1answer
128 views

VMware - Host two VPS with same IP

I have: 1 Dedicated server, Windows server 2008. 2 Virtual machines inside the server. (VMware, Windows too) 1 example IP address: (0.0.0.1) 1 example IP address: (0.0.0.2) I need: 1 Dedicated ...
0
votes
1answer
22 views

Information about SYN [closed]

I'm new to socket programming and i read that SYN packet can be created through a raw socket .But windows api doesn't allow the creation of a raw socket .I know that ICMP packet doesn't have any port ...
3
votes
3answers
589 views

How to prevent TCP ZeroWindow on writing a large file to a Windows share?

I've been given access to a share on a Windows Server 2003 SP1 system (10.a.bbb.ccc) which is a file and printer server, and regularly large files get copied to that share. However, occasionally such ...
4
votes
1answer
1k views

Too many TCP connections causes disconnections

I have a game server which runs with TCP connections. Server disconnects users randomly. I think its related with TCP settings of server. In local development environment written code can handle ...
2
votes
1answer
366 views

Is ECN (Explicit Congestion Notification) turned on by default on Windows Server 2012?

In a company network I noticed that all examined Windows Server 2012 machines had ECN turned on: > netsh interface tcp show global TCP Global Parameters ...
0
votes
1answer
63 views

Route TCP responses (ACK) through another interface

For reasons I can't go into, I am working with a strange network configuration. I have a one-way higher speed wireless link, and a slower bi-directional wireless link. There is a network interface ...
0
votes
1answer
258 views

Why do some connections time out and others get refused?

I have noticed that sometimes while trying to telnet in some random port, I have observed two kind of scenarios: $ telnet example.com 3432 Trying 173.252.110.27... $ telnet example.com 3432 ...
2
votes
1answer
1k views

Netstat -s showing (and growing) “packets pruned from receive queue” and “packets collapsed in receive queue”

we are seeing the following: [root@primary data]# netstat -s | grep buffer ; sleep 10 ; netstat -s | grep buffer 20560 packets pruned from receive queue because of socket buffer overrun ...
1
vote
0answers
40 views

IIS6 poor throughput from higher latency

I've been having a crazy issue with Windows 2003 + II6 where the throughput goes down as the latency goes up. This is exactly the type of thing that TCP Window scaling is supposed to solve so I ...
1
vote
2answers
166 views

Can a duplicate computer name be known before attempting to join the domain?

Techs in the field are deploying windows 7 pcs onto a domain. They complete one entry screen, which should give them a unique computer name. However, they are human and end up giving the pcs the ...
1
vote
1answer
1k 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 ...
-3
votes
2answers
181 views

Linux : Send a tcp message to a url/endpoint [closed]

I want to send a xml message to a URL like tcp://localhost:6060/services/test What are the available tools for this?
0
votes
3answers
95 views

TCP application accessible remotely but not locally

I am trying to help a friend figure this out, so I don't know all the details, but I figured I would post on here to see any possibilities. We have a custom application that communicates using a ...
1
vote
1answer
83 views

Will traffic control software cause tcp packets to be dropped

I am testing our client-server applications using NetLimiter which is a traffic control software. I found that, when client is receiving files from server and I use NetLimiter to set the download rate ...
0
votes
3answers
191 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 ...
1
vote
1answer
156 views

TCP RWIN, MSS and MTU [closed]

I have been doing some reading into TCP Receive Window (RWIN), Maximum Segment Size (MSS) and Maximum Transmission Unit (MTU). Right off the bat I have some questions and I need a power user's help! ...
0
votes
0answers
204 views

How to interpret findings on TCP Send/Recv Buffers

I have an application running on a CentOS machine that connects to a remote DB server on another CentOS machine. Every once in a while, without any discernable warning signs, the application seems to ...
2
votes
2answers
121 views

Is TCP RWIN set by application or OS?

I have a situation where an application is listening on a TCP port and every once in a while, as seen in tcp dumps, gets its Receiving Window (RWIN) set to zero. When this happens, its Recv-Q stops ...
1
vote
1answer
45 views

How to diagnose why a port is broadcasting a “ZeroWindow” status

I have two CentOS servers (one is an app server, the other is a DB) communicating over a port. Every once in a while, the application server starts broadcasting that the port connected to the DB has a ...