> That is a surprising revalation; that iptables filters traffic depending on Linux implementations details. One could imagine the outcry if firewall vendor X s

> That is a surprising revalation; that iptables filters traffic depending on Linux implementations details. One could imagine the outcry if firewall vendor X suffered a similar “feature”. Or is this well known for Linux iptable users? All of these major Linux firewall features have been around for over two decades and the use of multi-stage rule routing with filters is day-to-day for anyone in network ops. Cisco switches I messed with in the 90s had DHCP helpers for relaying packets across VLANs among other similar features. FTP helpers were extremely common before SSL/TLS/sftp became standard due to NAT and how the port directions work in that protocol.