Adding a rule with invalid interface name

[Swapnil Nagle]

iptables lets me add a rule with invalid interface name :

# iptables -A FORWARD -i abc -o xyz -j ACCEPT

This is the actual command. "abc" & "xyz" are not the obfuscated 
versions of some real interface names.

# iptables -L

Chain INPUT (policy ACCEPT)
target     prot opt source               destination

Chain FORWARD (policy ACCEPT)
target     prot opt source               destination
ACCEPT     all  --  anywhere             anywhere

Chain OUTPUT (policy ACCEPT)
target     prot opt source               destination

iptables version is 1.2.7a running on a stock RedHat 9 kernel (2.4.20-6)

Regards,
Swapnil.