Id still love to see qemu and thus kvm support tcp keepalives as an option for the serial telnet server. However I think I have a half decent work around. I defined a new type of console connection in conserver which first ssh's to the server then runs a telnet to localhost. This way ssh gives me a lot of extra options as far as keepalives and session disconnect detection and then when it goes down it locally tears down the shell/telnet very nicely. So far I havn't had any issues. One key was to use -t with ssh so that ctrl chars and local echo worked as expected. I'm always interested in other ideas but that's what I ended up doing. -denis On Sat, May 19, 2018 at 10:29:38AM -0400, Denis Hainsworth wrote: > As far as I can tell there is no way to enable tcp keepalives within kvm > for its telnet server serial console config. Just checking that this > would be a feature request and not something I'm missing. Or if folks > have any thoughts on a workaround. > > Currently when I set up linux vms in kvm I want serial console with > logging. For this I use the conserver package externally to connect to > the kvm host telnet based virtual serial ports using something like this > ex. from proxmox -serial tcp:0.0.0.0:2001,server,nowait > > This works fantastic 99% of the time. The only times it gets annoying > is when my conserver application (telnet clients) goes down uncleanly > leaving the telnet server connections in the ESTABLISHED state. Then > new telnet connections to say port 2001 on the host shows nothing. > > So far to clear this each VM has to be stop/started to tear down the > hung tcp sessions. Historically this sort of thing is solved with tcp > keepalive functionality on the server sockets. > > I'm not missing some deep hidden config to enable tcp keepalives on the > telnet server sockets right? > > potential workarounds: > > o run conserver locally on each host. a good bit of extra work for each > host. serial console logging ends up on each host instead of one > central conserver host. not perfect but may be workable. > > o look into netfilter conntrack setting on the host to tear down idle > established sessions. without some form of keepalive will need to make > sure the valid telnet sessons get re-established regularly which i think > is possible with conserver but need to check. > > -denis > > -- > __________________________ > Denis Alan Hainsworth > denis.hainsworth@xxxxxxxxx -- __________________________ Denis Alan Hainsworth denis.hainsworth@xxxxxxxxx
