xrandr -не может установить полноэкранный режим

Протокол TCP Keep -был определен в то время, когда даже концепция брандмауэра, не говоря уже о брандмауэре с отслеживанием состояния или NAT, вероятно, не была широко распространена. Из RFC 1122(октябрь 1989 г.):

4.2.3.6 TCP Keep-Alives

Implementors MAY include "keep-alives" in their TCP
implementations, although this practice is not universally
accepted. If keep-alives are included, the application MUST
be able to turn them on or off for each TCP connection, and
they MUST default to off.

Keep-alive packets MUST only be sent when no data or
acknowledgement packets have been received for the
connection within an interval. This interval MUST be
configurable and MUST default to no less than two hours.

[...]

Основная идея в то время заключалась не в потере информации о состоянии:

DISCUSSION:
A "keep-alive" mechanism periodically probes the other
end of a connection when the connection is otherwise
idle, even when there is no data to be sent. The TCP
specification does not include a keep-alive mechanism
because it could: (1) cause perfectly good connections
to break during transient Internet failures; (2)
consume unnecessary bandwidth ("if no one is using the
connection, who cares if it is still good?"); and (3)
cost money for an Internet path that charges for
packets.

[...]

A TCP keep-alive mechanism should only be invoked in
server applications that might otherwise hang
indefinitely and consume resources unnecessarily if a
client crashes or aborts a connection during a network
failure.

Я просмотрел обновленные RFC, но не смог точно упомянуть о сохранении активности.