Keep ssh tunnel alive

[ahuillet]

SSH through a NAT will often stop working after some idle time. The "real" solution is to add ServerAliveInterval to ssh_config.

We should either pass this to the ssh tunnel command, or implement a heartbeat mechanism.

As it stands, my Xpra sessions die after about 2h of idle.

[ahuillet]

-o ServerAliveInterval=300 on ssh commandline solves the problem. I propose adding that by default.

[Antoine Martin]

My understanding of ssh is that specifying -o OPTION overrides whatever is in the user's config file, so we probably don't want to do that.
Some users may have a low alive-interval set, others not, it should really be up to them to set this value - and they can do that already, in a much more flexible way (per host, etc) via ~/.ssh/config

Maybe we should just enable pings in xpra with a reasonable delay (currently the pings are enabled only when displaying statistics and are sent every second)

[Antoine Martin]

please close as 'wontfix' when the launcher is ready

[Antoine Martin]

note: --enable-pings will send a ping every second, which will effectively keep the session alive, we may want to make the delay configurable and replace this with --ping-frequency=N

[Antoine Martin]

r1007 enables pings unconditionally with a delay of 20 seconds.
--enable-pings now only increases the frequency of pings to 1 per second.

This should detect dead connections.