What's the difference between these two tools?
Can anybody tell me what the main workflow of networking behind Linux (in relation to IPv4 packet filtering, NAT and IP routing table) is?
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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.
There are many diagrams that are out there that illustrate exactly how a TCP/IP packet traverses the kernel (including Netfilter and the routing facility) - an example is this: http://www.adminsehow.com/2011/09/iptables-packet-traverse-map/