Iptables vs route

ref: https://superuser.com/questions/419659/iptables-vs-route

route is a command that displays, adds and deletes entries from the kernel’s TCP/IP routing table (aka “Forwarding Information Base”).

iptables is a command that displays, adds, and deletes entries from Netfilter, the Linux kernel’s packet filtering and manipulating subsystem. It handles NAT.

Since IP forwarding, i.e. routing, is basically rewriting a packet with a different source address and shipping it out of a different network interface, I believe you could technically do static routing with the proper iptables rules in the mangle table, but I believe it’s generally fastest to let the routing part of the kernel do that.

How a TCP/IP packet traverses the kernel (including Netfilter and the routing facility)