troubleshooting Question

DHCP on subinterface in FreeBSD

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rmarriner asked on
Networking
4 Comments1 Solution1523 ViewsLast Modified:
Ok, this might be a yes or no question.  I am running FreeBSD 5.2-Release on a home box as a Cable Router/NAT Gateway.  My question is whether or not I can use DHCP on a sub-interface (alias interface).

I added this
ifconfig_de0="DHCP"
ifconfig_de0_alias0="DHCP"

to my rc.conf but when I do a "ifconfig" I don't see it at all, just the actuall interface and no aliases.
#ifconfig
de0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> mtu 1500
        inet6 fe80::2c0:f0ff:fe37:8720%de0 prefixlen 64 scopeid 0x1
        inet 67.*.*.* netmask 0xffffff80 broadcast 255.255.255.255
        ether 00:c0:f0:37:87:20
        media: Ethernet autoselect (10baseT/UTP)
        status: active
xl0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> mtu 1500
        options=b<RXCSUM,TXCSUM,VLAN_MTU>
        inet 192.168.1.1 netmask 0xffffff00 broadcast 192.168.1.255
        inet6 fe80::250:daff:fe1c:311d%xl0 prefixlen 64 scopeid 0x2
        inet 192.168.1.100 netmask 0xffffffff broadcast 192.168.1.255
        ether 00:50:da:1c:31:1d
        media: Ethernet autoselect (100baseTX <full-duplex>)
        status: active
plip0: flags=8810<POINTOPOINT,SIMPLEX,MULTICAST> mtu 1500
lo0: flags=8049<UP,LOOPBACK,RUNNING,MULTICAST> mtu 16384
        inet 127.0.0.1 netmask 0xff000000
        inet6 ::1 prefixlen 128
        inet6 fe80::1%lo0 prefixlen 64 scopeid 0x4

I am running NATD on the internal interface (xl0) and de0 is the external interface.
What I am wanting to do is

real_ip1 -----
                   \                                                                ---- LAPTOP
                    \                                                             /
                     -----   BSDBOX                                       /
                     -----   acting as router  ----- SWITCH -----
                    /                                                            \
                   /                                                              \
real_ip2 -----                                                                 ---- DESKTOP

Ok... This is what I want it to look like.  But I would like for "real_ip1" to go to BSDBOX, which it does now...  "real_ip2" I would like on a subinterface on the same NIC as "real_ip1".   If somebody were to come in via "real_ip1" it would go to the BSDBOX, "real_ip1" would also be used for NAT for the Laptop.  If somebody were to come in via real_ip2 I would like the BSDBOX to basically forward everything from that IP directly to DESKTOP (basically DMZ).

Is all this fiasco possible?  At this point my road block is getting the DHCP on the subinterface.  But if the rest of the setup isn't possible I am not going to continue to try to get it working.

Thank You
Richard Marriner
richard at syix dot com
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