Proxy problem: "imap-login: Error: proxy(USERNAME): connect(10.x.x.178, 993) failed: Cannot assign requested address (after 0 secs, local=10.x.x.104)"

[brd]

Ralf Hildebrandt wrote:
[...]
> We already optimized:
> ---- snip ----
> net.ipv4.tcp_fin_timeout=5
> # down from 30s
> net.ipv4.tcp_tw_reuse=1
> net.ipv4.tcp_tw_recycle=1
> # http://redis4you.com/articles.php?id=012&name=Redis+high+traffic+connection+issue

just a note on enabling tcp_tw_recycle, it is known to have side-effects
and issues when you have lots of connections from the same source IP, such
as many clients behind same NAT IP or a reverse proxy

see http://vincent.bernat.im/en/blog/2014-tcp-time-wait-state-linux.html

-brd