Question
Should I enable "tcp_tw_reuse" on my server?
Answer
Please note that this setting affects the networking configuration of the server. We do not recommend making any changes to this setting unless you have been specifically instructed to by a System or Networking Administrator.
The configuration tcp_tw_reuse allows reusing a client port immediately after the connection has been closed, even if the connection is still in TIME_WAIT state. The default configuration of this setting is normally preferred.
For many older kernels, this setting defaults to '0,' Disabled. Modern kernels have expanded the definition of this setting to include three options: '1' Global, '2' Loopback Only, and '0' Disabled, where the default setting is '2.'
This setting should remain either Disabled or Loopback Only when communication with hosts behind a NAT firewall must occur. Otherwise, you might encounter TCP connection issues after applying this configuration parameter.
The most known issue causes clients behind a NAT to receive the following error when connecting via FTP:
425 Unable to build data connection: Connection refused