The tcp tag has no wiki summary.
1
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0answers
29 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
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2answers
45 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 ...
4
votes
3answers
50 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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0answers
42 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
32 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
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1answer
79 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 ...
0
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1answer
97 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
29 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, ...
1
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1answer
61 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 ...
2
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1answer
73 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 ...
21
votes
1answer
437 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 ...
1
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3answers
235 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 ...
2
votes
1answer
321 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...
...
0
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0answers
177 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
vote
2answers
237 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 ...
3
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2answers
276 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 ...
2
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1answer
73 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 ...
2
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3answers
305 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 ...
1
vote
1answer
127 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
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2answers
87 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
101 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 ...
0
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3answers
131 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.
2
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1answer
166 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
325 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 ...
1
vote
1answer
333 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 ...
3
votes
2answers
233 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 ...
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
483 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 ...
12
votes
4answers
563 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 ...
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
171 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
244 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
98 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
280 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 ...
1
vote
3answers
268 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 ...
2
votes
1answer
708 views
Run nmap via Tor
Is it possible to runnmap via Tor?
When I googled around, I got the impression that Tor uses Polipo / Privoxy, which are socks5 proxies. So any TCP / UDP aware applications should be able to use them ...
3
votes
3answers
238 views
How to measure the time when a packet arrives?
When the packet arrives the NIC generates an interrupt and the kernel then takes over. I want to measure the time at which a packet of a particular TCP flow arrives.
How do I do this in Linux? This ...
2
votes
1answer
169 views
Why does this simple Perl client not work?
I am fairly new to IPC with sockets and expect this issue is a simple one to resolve.
I'm trying to understand why I cannot get this example script from perldoc perlipc to run on my Ubuntu setup:
...
3
votes
2answers
4k views
Linux Networking routing to virtual ip addresses from a different subnet
New to linux networking, had a question about routing to virtual ip addresses from a different subnet.
I have three servers (they can all ping each other):
A 10.10.51.182 (connected to router ...
4
votes
3answers
287 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 ...
0
votes
2answers
158 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 ...
3
votes
1answer
1k views
Kill TIME_WAIT sockets immediately?
Is there anyway to kill those TIME_WAIT sockets immediately ? e.g output of netstat:
tcp 0 0 127.0.0.1:8080 127.0.0.1:41500 TIME_WAIT -
tcp 0 ...
15
votes
1answer
2k 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 ...
7
votes
3answers
2k views
Using in/out named pipes for a TCP connection
I've been fiddling with getting this to work for a while now, so I suspect some sort of fundamental misunderstanding about how pipes work is the root cause of my troubles.
My goal is to initiate a ...
2
votes
3answers
220 views
How can I read lines at a fixed speed?
I need to read a large log file and send it over a local network using (netbsd) netcat between two VMs on the same host workstation.
I know that netcat has an interval, but as far as I can tell, the ...
2
votes
1answer
669 views
/dev/tcp not present in Linux
I am porting C/pro*c code from UNIX to Linux. The code is:
#define __NFDBIT (8 * sizeof(unsigned long))
#define __FD_SETSIZ 1024
#define __FDSET_LONG (__FD_SETSIZ/__NFDBIT)
typedef struct ...
3
votes
1answer
223 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, ...
3
votes
1answer
270 views
User associated with a socket
I use ss -p to see TCP sockets information. But process info are not printed for some sockets. Below:
$ ss -p4
State Recv-Q Send-Q Local Address:Port Peer Address:Port
ESTAB 0 0 ...
1
vote
1answer
281 views
How to limit all tcp traffic to the network interface the session was initiated on?
I have an embedded linux system with two network interfaces (lan0, wlan0) that are configured to the same subnet. A server on this system accepts tcp connections on both interfaces.
How I can assure ...
