[strongSwan] Services unreachable after first connection

Tobias Brunner tobias at strongswan.org
Fri Jun 5 10:12:16 CEST 2020

Hi Tas,

> Do you think this strange behaviour can be cause by our strongswan
> configuration?

One thing that comes to mind in regards to TCP over IPsec are MTU/MSS
issues [1].  But those would only have an effect on larger transmits,
not on the initial TCP handshake.  That is, you should be able to create
a new TCP connection even after another stalled.  If that's not the
case, some firewall or routing issue could be the culprit (or a problem
with the IPsec tunnel on the other end).

By the way, you'll never see outbound plaintext traffic (e.g. a TCP SYN)
in tcpdump [2].



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