Killing tcp connection in linux

tcp

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 command line without restarting the server?

After search I found solution called as tcpkill. But it will not work for me. As it permanently blocks that ip.

Best Answer

On linux kernel >= 4.9 you can use the ss command from iproute2 with key -K

ss -K dst 192.168.1.214 dport = 49029

the kernel have to be compiled with CONFIG_INET_DIAG_DESTROY option enabled.

Related Solutions

SSH – How Does TCP-Keepalive Work in SSH

You probably want to use the ServerAlive settings for this. They do not require any configuration on the server, and can be set on the command line if you wish.

ssh -o ServerAliveInterval=5 -o ServerAliveCountMax=1 $HOST

This will send a ssh keepalive message every 5 seconds, and if it comes time to send another keepalive, but a response to the last one wasn't received, then the connection is terminated.

The critical difference between ServerAliveInterval and TCPKeepAlive is the layer they operate at.

TCPKeepAlive operates on the TCP layer. It sends an empty TCP ACK packet. Firewalls can be configured to ignore these packets, so if you go through a firewall that drops idle connections, these may not keep the connection alive.
ServerAliveInterval operates on the ssh layer. It will actually send data through ssh, so the TCP packet has encrypted data in and a firewall can't tell if its a keepalive, or a legitimate packet, so these work better.

Linux – How were these Linux TCP default settings decided

RFC 1122 specifies in section 4.2.3.6 that the keep-alive period must not default to less than two hours.

Best Answer

Related Solutions

SSH – How Does TCP-Keepalive Work in SSH

Linux – How were these Linux TCP default settings decided

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