===== PuTTY sessions unexpectedly close after they are idle for a while =====

> Some types of firewall, and almost any router doing Network Address Translation (NAT, also known as IP masquerading), will forget about a connection through them if the connection does nothing for too long. This will cause the connection to be rudely cut off when contact is resumed.
> You can try to combat this by telling PuTTY to send //**keepalives**//: packets of data which have no effect on the actual session, but which reassure the router or firewall that the network connection is still active and worth remembering about.

  * http://www.chiark.greenend.org.uk/~sgtatham/putty/faq.html#faq-idleout
  * http://tartarus.org/~simon/putty-snapshots/htmldoc/Chapter4.html#config-keepalive

{{tag>openssh timeout keepalive putty}}