5
votes
6answers
438 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 ...
1
vote
2answers
71 views

How to map an ephemeral port to a pid?

I have a RHEL server with several apps on it and I am attempting to figure out which one of them is making calls to an external web service. I have TCP dumps that show the calls being made and through ...
3
votes
1answer
378 views

Linux - TCP Source Port Reuse (and delay)

We have an application making a lot of calls to a remote web server/service. Client app is JBoss/Java on Linux (Red Hat 5), remote server is Windows 2008. There is a Cisco ACE in the way but there ...
0
votes
0answers
14 views

Display number of bytes transferred over a port

how can i display the number of bytes transferred over a certain tcp port? I know there are several tools (iptop,iptables...) which can monitor this, but what i need is an absolute counter. I poked ...
3
votes
3answers
723 views

How do high traffic sites service more than 65535 TCP connections?

If there is a limit on the number of ports one machine can have and a socket can only bind to an unused port number, how do servers experiencing extremely high amounts (more than the max port number) ...
1
vote
2answers
140 views

How can I release a port that is still in use but not bound to a process?

I'm running a Python application that spawns multiple processes. It uses port 56008 to listen for client requests. Sometimes after closing it the port it used is still "in use". There are still some ...
3
votes
1answer
185 views

How to disable Xvfb using TCP ports when using pyvirtualdisplay (Python)?

Trying to use pyvirtualdisplay for Python to start some applications with a virtual Xvfb X terminal. However, we've seen port clashes and would like to disable Xvfb from using TCP ports. I have ...
1
vote
1answer
52 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 ...
3
votes
2answers
1k views

is TCP port exhaustion real? [closed]

How fast would one need to allocate ephemeral ports in order to get into the TCP port exhaustion condition? I was told there are ~4k (older Windows), ~16k (newer Windows) or ~28k (RH Linux) ports ...
5
votes
5answers
3k views

Many ISP's is block port 25, how do I choose an alternative port?

I am building an application that will be acting as a combined MUA/MTA on different networks. However, many of the networks are with ISP's that block port 25 for SMTP. Therefore I would also like to ...
0
votes
1answer
128 views

Is there software that will convert bidirectional TCP traffic from one port to another? [closed]

I have an application that needs to send and receive traffic on a certain TCP port, say 5000. The server component uses port 6000. Is there any software that will allow me to "TCP bridge" these ...
0
votes
1answer
562 views

Mountain Lion, How can I release port?

$ netstat -ltanp tcp | grep 8000 | grep LISTEN tcp4 0 0 *.8000 *.* LISTEN I want to release this port When I do $ lsof -i:8000 I get nothing I ...
1
vote
1answer
73 views

Can multiple servers listen on the same port when no Bind/Accept has occured

When you have a Windows machine (server or home edition) which is running 2 servers, and they are both listening on port 4000, however none have had a request to connect? What happens when a client ...
1
vote
1answer
189 views

centos iptables, restrict tcp port to specific ips

I would like to modify the iptables on my CentOS 5.8 server so that only specific ips can connect to the machine on a specific port. Currently, I have the following in my iptables file: -A ...
3
votes
2answers
2k views

How to determine which TCP/UDP ports are being opened by a given process (linux)?

I know how to do the opposite (find out what process has a given port open) using lsof or netstat, but extensive research on Google hasn't helped me solve the reverse problem. I know I could use ...
2
votes
2answers
184 views

Which TCP ports to use?

Is there a TCP port range which I can be sure will not be used by anything else for traffic between two machines? If I am reading RFC6335 correctly, I can be sure that no other applications will use ...
0
votes
3answers
298 views

TCP Port prioritizing on switch/router (QoS)

I have some HP ProCurve series Switch. There is a QoS option for prioritize traffic by TCP/UDP port. I set two ports: one with highest priority and another with lowest. Then I performed tests to ...
0
votes
1answer
228 views

fast opening and closing connection with a specific port

We have a Main application named "Trevor" installed in 2008R2 machine named "TEAMER12" which is slow now. One more application named "TVS" also running in and found there were many connections per ...
1
vote
2answers
681 views

Port is open on machine A but it is not visible from machine B in Nmap

I have a virtualized CentOS machine with a software that is listening on port 8080. I have turned off SELinux and flushed all iptables (so now there are no rules set). I have checked with netstat -nap ...
2
votes
4answers
2k views

how to check connectivity to server by windows tools?

I need to check if client can connect to server on specific TCP port. Server is listening on it. Tried "telnet server_IP port" but telnet is stuck when I see that it's connected to the server. Seems ...
1
vote
2answers
619 views

Windows Server 2008 - unable to bind any TCP port

OS: Win Server 2008 RC2 Windows firewall on (no effect when off) I have suddenly been plagued by an issue in which I cannot find any similar ones with a search. I am running about 20 game servers ...
0
votes
1answer
374 views

Can't reach my server on some tcp ports from outside

I cant reach my server from outside in some ports like 4280 (proserver) or 10000 (webmin). If i telnet from localhost i can reach. I have installed iredmail. I don't know how i can diagnose the ...
3
votes
2answers
193 views

Port Knocking and TCP/IP within the OSI model

I have read that Port Knocking can be subject to false negative (type II error) due to the optimization techniques of TCP/IP. A correct port knock given by the client may be read as incorrect by the ...
-3
votes
1answer
519 views

how to open tcp port in ubuntu

I have a ubuntu server How can i open a port ? I have flushed the iptables and off'ed ufw Provide me steps how to open a tcp port
13
votes
5answers
5k views

Understanding Ports: How do multiple browser tabs communicate at the same time? [closed]

I realized today that I fundamentally don't understand how port communication works. If I fire up an instance of a webserver listening on port 80, it can respond to many requests from many different ...
0
votes
1answer
242 views

How do I determine if a certain port is being blocked?

I've wrote a .NET WCF service I put onto a Windows Server 2003 R2 server several months ago. I've not been able to work with it since, due to other job related responsbilities, but now am trying to ...
1
vote
4answers
147 views

How to find the program responsible for a specific TCP socket (linux)

joe@server:~$ sudo lsof -i :36168 COMMAND PID USER FD TYPE DEVICE SIZE/OFF NODE NAME java 23059 activemq 15u IPv6 109382 0t0 TCP *:36168 (LISTEN) From the output above I want ...
1
vote
4answers
784 views

Close tcp port with no process

I ended up in situation with a TCP port in listen mode with no process assigned to it. Is there a way to close this port without restarting server? Checking port status: me> netstat -tan | grep ...
0
votes
2answers
216 views

Is an Apache use TCP port on each connection?

Our system admin said "Apache use a TCP port on each connection" so A server can serve 65534 (MAX) simultaneously. is it Right? I think Apache use only 80 or 443. But , he use many file descriptor ...
1
vote
2answers
145 views

Can't access server use domain name, got tcp flag RST

I have a http sever provide service to internet, so I configured port forward in router. It’s fine for users access server outside company (URL: _http://mydomain.com:80/). But if the user is inside ...
0
votes
4answers
124 views

FC14 available TCP ports?

I am installing an application on Fedora Core 14 that uses a lot of sockets (eight of them) for TCP communication between various servers, all running on the same localhost. I've been trying to find ...
2
votes
2answers
977 views

socat connect-connect “proxy” two inbound TCP connections to expose a firewalled service?

I'm struggling a bit trying to see how to use socat (or a similar TCP port redirector) to expose a firewalled service on a PC. Here's the scenario: I have a server PC which will be acting as a ...
2
votes
1answer
1k views

Cannot start listening on a certain TCP port, but there's nothing currently listening on it

I have Windows Service that uses a WCF service host to listen for connections on TCP port 61000. When I try to start the service, I get the error: Service cannot be started. ...
3
votes
2answers
1k views

OpenBSD has open ports in default installation

I have been considering replacing Ubuntu with OpenBSD to improve the security on my local server. I need to have ssh access to it, and I also need it to serve static web content - so the only ports I ...
4
votes
4answers
551 views

Why was the FTP protocol designed to use more than one port?

The question is in the title. The reason I wonder this is because I'm coding an tcp service and would like to explore some of the reasons as they may shed some light on my work.
1
vote
1answer
297 views

Determine the Ports reserved and what service reserved them in Windows XP/2003

this question is always rise. How can i know what ports are currently reserved in windows XP/2003 and what service had reserved them. for example when i want to install Apache, default port will be ...
1
vote
1answer
793 views

Windows Server 2008 constantly spamming external IP's on outbound TCP port 445

I have a Windows Server 2008 box running as a Domain Controller. I have noticed in my Cisco ASA firewall logs that this box is continuously sending out (like a thousand requests a second) requests on ...
0
votes
4answers
373 views

What's port 1283?

I see a lot of connection attempts to 1283/tcp on my firewall from a client computer to a Windows Server 2008 Domain Controller. What exactly is this traffic? Something to do with NetBIOS, perhaps?
0
votes
5answers
2k views

Lingering tcp connection in LISTEN state

My java application can sometimes be killed by an external script. This can be done either with SIGTERM or with SIGKILL. The application is a server which receives many connections per second, and it ...
1
vote
1answer
148 views

What does it mean that most dropped packets have a different incoming and outgoing port?

Over the weekend an internet-facing DI-624 router of mine was e-mailing me logs like crazy for some reason. Normally it's a few a day, but it was about one every few minutes instead. Analyzing the ...
2
votes
1answer
686 views

TCP: Address already in use exception - possible causes for client port? NO PORT EXHAUSTION

stupid problem. I get those from a client connecting to a server. Sadly, the setup is complicated making debugging complex - and we run out of options. The environment: *Client/Server system, both ...
0
votes
2answers
948 views

What port does OpenLink ODBC Driver use?

I use Avaya Reporting Services and OpenLink ODBC Drivers for db connection. I know that it uses port 5000 for handshaking but after that I believe it uses an random port for communication. I want to ...
4
votes
2answers
6k views

Should I use TCP or UDP to run a web server

I have just installed Apache web server on my computer. I have managed to use it locally (I can open index.php from my computer using my web browser). But I would like to make my web site available ...
3
votes
1answer
323 views

Do NATs verify the source port of a SYN received after a SYN has been sent?

I'm unsure of whether this question is more appropriate for stackoverflow or serverfault. If you think it's more suited for stackoverflow, let me know and I'll delete this and move it over. I have a ...
4
votes
5answers
308 views

Which ports to use on a self-written tcp server

I am about to write tcp-server for a project my company is working on. The server will use several port for different tasks. During development we use just some portnumber we like: 1400, 1500, ...