Openssh not closing connections on service stop
Hi all,
I'd like to share with you what I consider a bug.
I've generally noticed in my Linux experience that I get automatically disconnected from an ssh session if the ssh host gets shutdown or rebooted with the message:
Connection to x.y.w.z closed by remote host.
Connection to x.y.w.z closed.
This doesn't seem to happen on my OSes built on core-image-minimal with openssh support.
Moreover I noticed that if I stop the ssh service:
# /etc/init.d/sshd stop my ssh connections don't get dropped, I can continue using ssh session like nothing happened. I can even see the connection process still up and running: # ps | grep ssh 1790 root 4568 S /usr/sbin/sshd 1848 root 4852 S sshd: root@pts/0 1886 root 2896 S grep ssh # /etc/init.d/sshd stop Stopping OpenBSD Secure Shell server: sshdstopped /usr/sbin/sshd (pid 1790) . # ps | grep ssh 1848 root 4852 S sshd: root@pts/0 1894 root 2892 S grep ssh
Isn't service termination supposed to stop all related connections at the same time? Can anybody else reproduce (or not) this issue?
Bests,
Diego
Quoted 10 lines · Diego
Hi all,
I'd like to share with you what I consider a bug.
I've generally noticed in my Linux experience that I get automatically disconnected from an ssh session if the ssh host gets shutdown or rebooted with the message:
Connection to x.y.w.z closed by remote host.
Connection to x.y.w.z closed.
Well this is because the machine is actually shut down or halted, therefore all processes get killed regardless, this is not necessarily a function of stopping the daemon
Quoted 18 lines
This doesn't seem to happen on my OSes built on core-image-minimal with openssh support.
Moreover I noticed that if I stop the ssh service:
# /etc/init.d/sshd stop my ssh connections don't get dropped, I can continue using ssh session like nothing happened. I can even see the connection process still up and running: # ps | grep ssh 1790 root 4568 S /usr/sbin/sshd 1848 root 4852 S sshd: root@pts/0 1886 root 2896 S grep ssh # /etc/init.d/sshd stop Stopping OpenBSD Secure Shell server: sshdstopped /usr/sbin/sshd (pid 1790) . # ps | grep ssh 1848 root 4852 S sshd: root@pts/0 1894 root 2892 S grep ssh
Quoted 3 lines
Isn't service termination supposed to stop all related connections at the same time? Can anybody else reproduce (or not) this issue?
It may actually be designed to work this way, since the daemon spawns a process for each login the daemon can be restarted on a headless or server type machine and not loose the connection, based on googling, I could not find this outright on the Openssh.com site.
It appears that the dropbear sshd also has the behavior.
So I would not call this a bug.
Sau!
Quoted 3 lines
Bests,
Diego
In data martedì 2 dicembre 2014 16:13:09, Saul Wold ha scritto:
Quoted 10 lines
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Quoted 2 lines
Isn't service termination supposed to stop all related connections at the same time? Can anybody else reproduce (or not) this issue?
It may actually be designed to work this way, since the daemon spawns a process for each login the daemon can be restarted on a headless or server type machine and not loose the connection, based on googling, I could not find this outright on the Openssh.com site.
Quoted 6 lines
It appears that the dropbear sshd also has the behavior.
So I would not call this a bug.
Sau!
Hi Saul,
I had a bit of a discussion with bluelightning and peteru in #oe. We came to the conclusion that having ssh connections still up after service stop is considered to be the correct behaviour.
On the other hand, not closing ssh connections on shutdown is generally considered a bug by distros, although it is considered a minor one. This generally requires connections being killed before network is brought down, which might be complicated with sysvinit. These are the links from other distros:
https://bugzilla.redhat.com/show_bug.cgi?id=626477
https://bugs.gentoo.org/show_bug.cgi?id=259183
https://bugs.archlinux.org/task/31250
Long story short: it would be nice to gracefully close ssh connections on shutdown before terminating network connections, but it's a minor issue, and probably not worth the effort of fixing.
Bests,
Diego