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EOIP works behind snat?

Posted: Sun Jul 26, 2020 9:28 am
by mafiosa
Hello my isp provides me static IP via snat. GRE works fine. Will eoip work behind SNAT? 115.187.xx.xxx is snatted to 10.28.115.18( ip on my router interface). Will it work?

Re: EOIP works behind snat?

Posted: Sun Jul 26, 2020 11:15 am
by sindy
It should work. However, there may be an issue - there is an optional ID field in GRE which RouterOS misuses. Whereas all four bytes are normally used as tunnel ID, in case of EoIP, two bytes are used for tunnel ID and the other two bytes hold payload size, so firewalls which track connections based on tunnel ID cannot match all packets to the same connection. So try and see.