tcp keepalive

• When TCP sockets refuse to die
  • SYN-SENT
  • SYN-RECV
  • Final handshake ACK
  • Idle ESTAB is forever
  • Keepalives with TCP_USER_TIMEOUT are confusing
  • Busy ESTAB socket is not forever
  • Zero window ESTAB is… forever?
  • Note about using application timeouts
  • Summary