How do I remove a CLOSE_WAIT socket connection

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I have written a small program that interacts with a server on a specific port. The program works fine, but:

Once the program terminated unexpectedly, and ever since that socket connection is shown in CLOSE_WAIT state. If I try to run a program it hangs and I have to force it close, which accumulates even more CLOSE_WAIT socket connections.

Is there a way to flush these connections?


CLOSE_WAIT means your program is still running, and hasn't closed the socket (and the kernel is waiting for it to do so). Add -p to netstat to get the pid, and then kill it more forcefully (with SIGKILL if needed). That should get rid of your CLOSE_WAIT sockets. You can also use ps to find the pid.

SO_REUSEADDR is for servers and TIME_WAIT sockets, so doesn't apply here.

HowTo: Kill TCP Connections in CLOSE_WAIT State, If you are seeing a large number of connections persisting in CLOSE_WAIT state, it's probably a problem with the application itself. Restarting it� A connection can (and quite correctly) stay in CLOSE_WAIT forever while the program holds the connection open. Once the local program closes the socket, the OS can send the FIN to the remote end which transitions you to LAST_ACK while you wait for the ACK of the FIN.


As described by Crist Clark.

CLOSE_WAIT means that the local end of the connection has received a FIN from the other end, but the OS is waiting for the program at the local end to actually close its connection.

The problem is your program running on the local machine is not closing the socket. It is not a TCP tuning issue. A connection can (and quite correctly) stay in CLOSE_WAIT forever while the program holds the connection open.

Once the local program closes the socket, the OS can send the FIN to the remote end which transitions you to LAST_ACK while you wait for the ACK of the FIN. Once that is received, the connection is finished and drops from the connection table (if your end is in CLOSE_WAIT you do not end up in the TIME_WAIT state).

Large number of CLOSE_WAIT sockets seen in "netstat" or "ss , Port 8081 running “JAVA.exe” has CLOSE_WAIT sockets. How to Kill Or Reduce TCP Close_Wait connections? Is there a way to terminate the� If you do get all the processes with a reference to the socket, the CLOSE_WAIT should go away. If indeed you have gotten all the processes with a reference to the socket, and it remains in CLOSE_WAIT, that indicates a bug in the stack.


I'm also having the same issue with a very latest Tomcat server (7.0.40). It goes non-responsive once for a couple of days.

To see open connections, you may use:

sudo netstat -tonp | grep jsvc | grep --regexp="127.0.0.1:443" --regexp="127.0.0.1:80" | grep CLOSE_WAIT

As mentioned in this post, you may use /proc/sys/net/ipv4/tcp_keepalive_time to view the values. The value seems to be in seconds and defaults to 7200 (i.e. 2 hours).

To change them, you need to edit /etc/sysctl.conf.

Open/create `/etc/sysctl.conf`
Add `net.ipv4.tcp_keepalive_time = 120` and save the file
Invoke `sysctl -p /etc/sysctl.conf`
Verify using `cat /proc/sys/net/ipv4/tcp_keepalive_time`

This is strictly a violation of the TCP specification, nc 127.0.0.1 5000 -v nc: connect to 127.0.0.1 port 5000 (tcp) failed: Connection timed out We noticed hundreds of CLOSE_WAIT sockets: I think socket.io will force-close these incorrectly connection after some timeout. But it seems like not work correctly. I try to reappear the state CLOSE_WAIT or FIN_WAIT2 problem in my test environment. But it never show up these connection situation. After connect socket server and disconnect network; Connect socket server for a long time


Even though too much of CLOSE_WAIT connections means there is something wrong with your code in the first and this is accepted not good practice.

You might want to check out: https://github.com/rghose/kill-close-wait-connections

What this script does is send out the ACK which the connection was waiting for.

This is what worked for me.

Killing CLOSE_WAIT sockets without killing parent process on Linux , I believe CLOSE_WAIT on the server side of the connection means that the server has received a FIN from the client, will have acknowledged this back to the � No, there is no timeout for CLOSE_WAIT. I think that's what the off means in your output. To get out of CLOSE_WAIT, the application has to close the socket explicitly (or exit). See How to break CLOSE_WAIT. If netstat is showing -in the process column: are you running with the appropriate privileges and capabilities (e.g. as root)?


It should be mentioned that the Socket instance in both client and the server end needs to explicitly invoke close(). If only one of the ends invokes close() then too, the socket will remain in CLOSE_WAIT state.

Solved: CLOSE_WAIT status, how to properly close the conne , CLOSE_WAIT status, how to properly close the connection. SOLVED then run this command to terminate the sockets. #ndd -set /dev/tcp� A socket remains in CLOSE_WAIT till the server does passive close and sending FIN packet back to client. Due to heavy thread activity the server thread might not get enough CPU cycle to do so. tcp_close_wait_interval suggests that solaris kernel to give up on orphaned close-wait sockets.


How I kill a process with suspicious TCP CLOSE_WAIT, How I kill a process with suspicious TCP CLOSE_WAIT development, we encontered a lot of connections are in CLOSEWAIT state, so that our -l N If a process has more than or equal to N CLOSE_WAIT socket(s), it will be� When temporary disconnection happens in the network, this can lead a CLOSE_WAIT state.This could indicate that the client properly closed the connection. But the server still has its socket open. But the server still has its socket open.


Why Does “netstat” Output Show Many Connections in , Closed, then remote shutdown; awaiting acknowledgment. CLOSE_WAIT, Remote shutdown; waiting for the socket to close. ESTABLISHED, Connection has been� linux - How do I remove a CLOSE_WAIT socket connection - Stack Overflow says: CLOSE_WAIT means your program is still running, and hasn't closed the socket (and the kernel is waiting for it to do so). Add -p to netstat to get the pid, and then kill it more forcefully (with SIGKILL if needed). That should get rid of your CLOSE_WAIT sockets.


Orphaned connections in CLOSE_WAIT state, I think that's what the off means in your output. To get out of CLOSE_WAIT , the application has to close the socket explicitly (or exit). See How to� Actually there is a way to kill a connection - killcx. They claim it works in any state of the connection (which I have not verified). You need to know the interface where communication happens though, it seems to assume eth0 by default. UPDATE: another solution is cutter which comes in some linux distros' repositories.