[Dxspider-support] Telnet connection keep alive

[jarmo]

Now have tested connection and noticed that it is my routers
firewall, what makes connection as "zombie", when there is not
much spots in early morning hours.

I bridged my router channel and use my linux firewall and it seems,
that connection does not drop into "zombie".

Dirk, could you explain "$user_interval", is it just probe
with no data and waiting "ACK" response? Or is it some kind of
ping?

Seems, that these router firewalls blocks quite roughly traffic :)
So, may need some kind of data, to keep connection alive?

Jarmo, oh1mrr