Re: sshd doesn't disconnect for 30+ minutes after the TCP connection is closed ungracefully

Reply: Mike Karels : "Re: sshd doesn't disconnect for 30+ minutes after the TCP connection is closed ungracefully"
In reply to: Yuri : "sshd doesn't disconnect for 30+ minutes after the TCP connection is closed ungracefully"
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From: Michael Gmelin <grembo_at_freebsd.org>
Date: Wed, 01 Mar 2023 11:36:32 UTC


> On 1. Mar 2023, at 11:35, Yuri <yuri@freebsd.org> wrote:
> 
> Windows system connects to FreeBSD through ssh and then this connection dies because of WiFi or VPN issues.
> 
> FreeBSD still has the sshd process alive for this connection for 30+ minutes.
> 
> TCP keepalive is enabled on the FreeBSD host:
> 
> $ sysctl net.inet.tcp.always_keepalive
> net.inet.tcp.always_keepalive: 1
> 
> Shouldn't TCP keepalive kill this sshd process after 3-4 minutes because this connection isn't alive?
> 

Keepalives start after net.inet.tcp.keepidle milliseconds (2h by default).

Cheers