I've been having the annoyance that my wife's Android like to spam my firewall log with blocked FIN packets trying to go from SRC:LAN DST:WAN, and I wanted to run this idea past you guys for correctness and to make sure I wasn't going to unintentionally mess something up.
I was thinking of blocking FIN packets on my LAN interface. What I am hoping for is that a FIN packet always comes after a SYN packet, so the state should exist in the firewall, so it should ignore that rule so long as it thinks the state is alive. But once the state is dead, if another FIN packet comes after, I could have it reject and not log. This would allow the client to immediately kill its local connection and it would stop spamming my log.
Does anyone see any possible issues and/or did I make any wrong assumptions?