Connexion SYN_RECV

Dear all,

Since 4 days, I upgraded to core 150 which solves several of my issues. I am very glad for this release indeed :slight_smile:

However, and I don’t think it is related to the upgrade, I have an issue with my computer at work. It is connected to internet with a static IP X.X.X.X. “What’s my ip” indicates the same X.X.X.X and all works except connections to my server. I can see the connections in the “connections” menu but the status of all tries from this IP is “SYN_RECV”

I tried several services, like web, openvpn, xmpp with and without NAT and always the same SYN_RECV.

My server behind NAT does not see the connection so I guess I have to solve this connection status before going further.

If I use the same computer with an IP in the same subnet I have the same problem but if I switch to wifi tethering it works. Of course the wifi is not on the same subnet. I looked at my ipfire logs. There is no DROP_INPUT so the IP is not blocked by iptables. And I don’t see anything related to this IP in my rules.

I read that SYN_RECV should be the first step for TCP connection with a reply from the server and back from the client. Could it be possible that my work drop somehow the reply ? As if it was a DDOS attack ?

Thanks for your help