The tcp tag has no wiki summary.
1
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3answers
213 views
rsh runs perfectly in normal user but not in root, very strange, why?
When I run command, rsh localhost pwd as a root
It shows below output.
connect to address 127.0.0.1 port 544: Connection refused
Trying krb4 rsh...
connect to address 127.0.0.1 port 544: Connection ...
1
vote
0answers
25 views
ssh will sporadically hang temporarily on fast connection
I am using Ubuntu 13.04 on my laptop, connected to my router at home. When working from home, I will ssh into the servers on campus, through a vpn, with X11 forwarding.
ssh -X ...
1
vote
2answers
41 views
Checking if I can reach some ports from my computer
Is there a terminal command or something on OSX that I can use to test if I can reach some ports on a remote server?
I know these ports are reachable on that server, because I can access them from ...
2
votes
1answer
71 views
Browser fails to reach any host on Solaris 8
I'm running Solaris 8 on a Sun Ultra 2 connected to a Verizon router. nslookup seems to work (it finds google.com) but the existing browser (Netscape 4.76 - yes - it's very old) fails to reach any web ...
1
vote
1answer
431 views
Port Mirroring in Fedora?
I have set up an application that listens constantly to a port for network packets, and I would like to create another one that receives the same network packets ( for use as a test bed). Getting the ...
4
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3answers
48 views
How does the server find out what client port to send to?
As I understand it this is what happens when a client makes a connection request:
The server will be bound to a particular port number. The port number is always bound to a listening process. Since ...
0
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1answer
28 views
What are the other congestion control algorithms specially designed for lossy Wireless Networks like LTE and WiMax?
I am trying different congestion control algorithms for getting maximum throughput and minimum delay across my setup for TCP flow.Please suggest other available algorithms apart from
Veno, ...
2
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3answers
294 views
Linux Shell Script - Send command over TCP to Sharp Aquos
I'm writing a shell script that needs to send an 8 character string terminated with a x0d to a Sharp Aquos TV. An example is 'POWR1 \x0d' (POWR1 followed by three spaces and LF)
The documentation ...
8
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1answer
580 views
Kernel socket structure and TCP_DIAG
I'm working on a software which connects to a Real Time data server (using TCP) and I have some connections dropping. My guess is that the clients do not read the data coming from the server fast ...
0
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3answers
130 views
How to send an email to myself on the same local machine (tcp port 25)
Does anyone know how to sent email to myself?
I am trying to generate TCP traffic on port 25.
8
votes
2answers
21k views
Orphaned connections in CLOSE_WAIT state
I've got a SLES machine that accumulates TCP connections in a CLOSE_WAIT state for what appears to be forever. These descriptors eventually suck up all available memory. At the moment, I've got 3037 ...
0
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0answers
41 views
What could be the possible reasons for bad performance of TCP over Wireless or Sate-lite networks ?
I am running a wireless network having Linux(fedora 17) at sender end.We decided TCP_veno is most useful for my network,so we are using it as default congestion control algorithm.Still, We are not ...
0
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1answer
95 views
How to display TCP handshake in Linux [closed]
Hi is there a way to display TCP handshake in Linux? Like for example this WIKI - TCP handshake
Not exactly like the illustration but at least it would show client has sent SYN, ACK, FIN etc
and the ...
0
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1answer
28 views
How to connect to port immedeately, avoiding socket_bind(): unable to bind address?
When running a code that is supposed to read from a TCP/IP port I often get the following message (depending exactly what language have been used):
socket_bind(): unable to bind address
I know that ...
1
vote
1answer
72 views
Killing tcp connection in linux
I have some dead connection in one application which is in hanged state if client machine is dead.
->192.168.1.214:49029 (ESTABLISHED)
Is there a way to terminate these option from linux ...
2
votes
1answer
69 views
How to run Different congestion control algorithms in FEDORA 17 ..?
Earlier versions of Fedora has different loadable kernel modules which includes diffrent congestion control algorithms etc at (/lib/modules/"kernel-name"/kernel/ipv4).These are present in the form of ...
1
vote
1answer
60 views
Using Wireshark on Linux to observe coupled HTTP-request and HTTP-respond
I use Wireshark on Linux to observe my HTTP traffic. Other programms like Firefox Live Http Headers show coupled http-request from my browser and http-respond from any server.
How using programs like ...
0
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2answers
157 views
Why my Http Proxy doesn't reply [SYN,ACK] after received a [SYN] packet from the client?
I have a http proxy running on Linux (RHEL 5.5), intermittently it doesn't reply [SYN,ACK] packet after received a [SYN] packet from the client. This issue can be recovered by restarting the proxy. I ...
2
votes
1answer
299 views
Why can't I use strace with rsh?
If I run rsh, it works, but prints some strange “Connection refused” messages at the beginning:
$ rsh localhost pwd
connect to address 127.0.0.1 port 544: Connection refused
Trying krb4 rsh...
...
21
votes
1answer
434 views
Why does it take up to several minutes to clean a listening TCP port after a program dies?
If I kill a program that is listening on a TCP port, it takes up to several minutes until the port is reclaimed by the system and usable again. I've seen several Q/A mentioning this phenomenon, but ...
0
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0answers
161 views
Turn off TCP checksum offload [closed]
I am programming a linux networking driver. It is almost done. When I ping between 2 PCs, everything is perfect. And then I try to use some TCP/UDP protocols, and the receiver never reply. I used ...
1
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2answers
215 views
Why TCP TIME-WAIT State is present at both ends after a connection termination?
I am reading how the TCP states work and especially the connection termination part.
All of the books or online material I read, shows that for the termination procedure these states are followed ...
12
votes
4answers
559 views
TCP dies on a Linux laptop
Once in several days I have the following problem. My laptop (Debian testing)
suddenly becomes unable to work with TCP connections to the internet.
The following things continue working fine:
UDP ...
3
votes
2answers
258 views
Getting current TCP connection count on a system
Instead of doing wc -l /proc/net/tcp, is there a faster way of doing it?
I just need a total count of tcp connections.
0
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0answers
38 views
How to tune Unix (Ubuntu) for web crawling?
What are some ways to tune some Unix settings in the kernel(or elsewhere) for web crawling purposes? I am using multi-curl, and am using a multi-threading approach. I've set a higher limit for maximum ...
1
vote
1answer
325 views
Is there a faster interface for info from /proc/net/tcp?
Given a linux TCP socket's inode (obtained via /proc/<pid>/fd), is there a faster way to look up the information that I can get from /proc/net/tcp about this socket?
I have written a ...
1
vote
1answer
125 views
Default value for SO_RCVTIMEO option on Solaris
Is there any way to find out what is the default value set for option SO_RCVTIMEO on Solaris 10?
If there is a way to find out how would one go about changing it?
P.S. I am aware of ability of ...
1
vote
2answers
83 views
Port forwarding and masquerading
What is the relationship between port-forwarding and masquerading?
If server A is configured to masquerade its clients, and client B accesses the Internet through server A,
then since client B is ...
5
votes
2answers
100 views
Is it more dangerous to connect to the net as root?
If I make some kind of tcp connection to the net as root, is that less safe then making the same tcp connection as a normal user?
I have been suspecting for a while that by making a connection as ...
2
votes
1answer
165 views
Running a local port scan and found open ports but, don't know what they're used for?
I wrote a very basic python script to port scan my system. I'm running linux-mint lisa:
open_ports = []
for port in xrange(65536):
conn = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
...
3
votes
3answers
316 views
What process is sending TCP SYNs on Solaris 10?
Some process on my Solaris 10 machine is sending TCP SYNs to a remote machine. The remote machine never responds, so the connection is not established. How do I find out what process is initiating ...
3
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2answers
225 views
Meaning of log entries from an iptables configuration
My router has Linux as its OS. The system log has a lot of rows about iptable and klogd that I don't understand, could someone explain them to me?
The iptables setup:
iptables -t nat -A PREROUTING ...
4
votes
3answers
282 views
How can I know the process name which is opening a tcp port?
I have two linux servers. Let's say they are C and S.
C is client of S
On my S machine, I type.
$ netstat -an | grep ESTABLISHED
tcp 0 0 192.168.1.220:3306 C:57010 ...
2
votes
2answers
2k views
Fast way to copy a large file on a LAN
I am having some trouble with NFS, and I'd like to try using just plain old TCP.
I have no idea where to begin, though.
Hardware-wise, I am using an ethernet crossover cable to network two netbooks.
...
2
votes
1answer
135 views
How do I ensure outbound TCP/IP traffic always uses a VPN, even when using Wifi?
I'd like to ensure that my VPN is started and running, before any TCP traffic from any of my background services send or receive data. How can I guarantee that this is the case?
How do I handle ...
1
vote
1answer
465 views
Adjusting rsync TCP timeout
I'm using rsync in my own C++ program by issueing the command system("rsync -rauzvq root@host:/folder");
I use this for keeping multiple systems in sync.
Now I have the problem that when a remote ...
2
votes
1answer
169 views
Closing socket connection on running console application
I am testing a chat bot and want to gracefully handle for times when the chat server isn't running so it can come back up when the service is available again. I have the programming handled. My ...
2
votes
1answer
242 views
Memory ussage for TCP or named pipe message buffers?
I have a group of programs that I was stress testing today. I drastically shot up the input load to the program and it worked at first, but I had an apparent memory leak sucking up memory. The only ...
3
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0answers
97 views
Socksifying a qemu-kvm using tsocks
I'm trying to socksify a qemu-kvm using tsocks, but I have no success.
I don't know if qemu access directly the hardware, skipping the OS or something like that, but I wasn't able to do this feat.
...
2
votes
2answers
273 views
What is the relation between DISPLAY :1.0 and port 5901
When I start a new X server using vncserver I can connect it using port 5901. From, say, a terminal, I can also do a:
export DISPLAY=:1.0
xterm
(it's just an example)
And I get an xterm on the ...
3
votes
2answers
120 views
How to detect out-bound port from PID
I have several applications that run on random ports. How would I take the pid or the file location and find which port it is running on?
Example of desired output:
www-data/apache = 80
...
3
votes
4answers
4k views
testing services/open ports with telnet?
I often see that folks test ports this way:
//shell
telnet ip-address 80
telnet ip-address 25
AFAIK telnet was the old way of getting onto some remote box - right? or so I thought...
Why exactly ...
4
votes
1answer
2k views
iptables port-mirroring
I need to be able to get a copy of packets received on port 8001 to port 8002. I have tried the following but I get an error that --tee is undefined.
sudo iptables -t nat -A PREROUTING -p TCP -s ...
0
votes
1answer
491 views
Can't connect remotely to server running redhat (ec2)
I created a RedHat 6.1 VM with EC2. Logged in as root, I installed (unzipped) JDK1.7 in /root/bin/jdk1.7.0 and installed (unzipped) GlassFish 3.1.1 in /root/bin/glassfish3. I set JAVA_HOME and ...
3
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2answers
390 views
How to listen to all ports (UDP and TCP) or make them all appear open in Debian
I got an external Debian server. The problem is that my university campus doesn't allow connections to go outside when the port is different than TCP port 22, 80, 443, or UDP port 123. I tested them ...
4
votes
2answers
3k views
How to configure SVN/SSH with SSH on non standard port?
I have configured SSH to be on port 20000. When I try:
svn co svn+ssh://server.com:20000/home/svn/proj1 proj1 --username jm
I get
svn: To better debug SSH connection problems, remove the -q ...
0
votes
1answer
165 views
php mail not working in rhel server?
I have installed roundcube mail and when it tried to use installer which uses php mail it is loading for 5 to 10 minutes and then telling me 'ok' but no mail comes to me. smtp_port is 25 host is ...
3
votes
1answer
222 views
Route incoming network requests for a given port to different applications
I have an application that listens for connections on a port, but I occasionally take it down for updates and the like. I'd like a way to configure the system such that if that program is running, ...
15
votes
1answer
1k views
Why doesn't Linux use the IANA Ephemeral port range?
According to Wikipedia
The Internet Assigned Numbers Authority (IANA) suggests the range 49152 to 65535 for dynamic or private ports. Many Linux kernels use the port range 32768 to 61000.
Even ...
1
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3answers
265 views
Books/Resources which explain TCP/IP kernel implementation [closed]
I only know about:
1) Internetworking with TCP/IP: Vol.II, Design, Implementation, and Internals
2) TCP/IP Illustrated, Vol. 2: The Implementation
but these are quite dated. I am particularly ...
