DragonFlyBSD not in compliance with RFC 1122

[Matthew Dillon]

:Hello,
:
:I ran into a problem today. I administer a machine that needs to sit on 
:two separate networks 192.168.2.2/24 and 192.168.15.2/24. The network 
:card is configured as:
:
:xl0: flags=8943<UP,BROADCAST,RUNNING,PROMISC,SIMPLEX,MULTICAST> mtu 1500
:         inet 192.168.15.2 netmask 0xffffff00 broadcast 192.168.15.255
:         inet 192.168.2.2 netmask 0xffffff00 broadcast 192.168.2.255
:         ether 00:10:5a:f7:6e:71
:         media: Ethernet autoselect (100baseTX <full-duplex>)
:         status: active
:
:The machine has a default route of 192.168.15.1.
:(Public IP addresses replaced with private.)
:
:All is well except that 192.168.2.2 is inaccessible from the Internet. A 
:quick RTFM reveals that I need to add a second default gateway but it 
:appears that this is not supported under FreeBSD 4 or DragonFly.
:
:http://lists.freebsd.org/pipermail/freebsd-i386/2003-October/000335.html

    We definitely do not support multiple default gateways, but having two
    internet-routable nets on the same interface ought to work as long as
    your default router can deal with it.  Make sure that 
    net.inet.ip.forwarding is set to 1 (via sysctl) and then you need to
    run some tcpdump's on that interface and check:

    (1) that the machine is receiving the ARP request to resolve 192.168.2.2.
    (2) that the machine is responding to the ARP request.
    (3) that the machine is receiving the packet meant for 192.168.2.2.
    (4) then see if the machine is replying to it (e.g. assuming it's a ping
	or something).  The reply should be going out your default route.
	(tell tcpdump to dump the MAC header too so you can be sure it is
	being sent to the box defined by your default route).

    There are several issues involved here.

					-Matt
					Matthew Dillon 
					<dillon at xxxxxxxxxxxxx>