Bart Dorlandt - BAMweb.nl

Default Settings

The default setting for my router is a routing modem. The DSL interface of the router gets the External IP address. The Lan interface has 172.19.3.1/24. It also has DHCP server enabled. This way a client gets an IP address within the 172.19.3.x/24 range and is able to communicate with the internet instantly.

Change to Bridge

I want to change the setup to a bridge because I want my server (OpenBSD) to get the external IP adres directly. This way I don't have to NAT or do some other spooky things.

1. Disable the DHCP server
2. Delete the current service within the WAN connections page
3. Leave your LAN interface with the IP adres you got, in my case 172.19.3.1
4. Create a new service
   1. RFC1483 bridged (RFC 1483/2684)
   2. VCI value = 34 for Tiscali (BabyXL), After pressing OK your modem isn't manageable
      • Versatel VCI = 32
      • BBned VCI = 35

Manageble bridge

I use OpenBSD as my server. I have configured the external interface as DHCP client.

$ cat /etc/hostname.xl0

dhcp NONE NONE NONE
up
rtsol

And I also edited my dhclient.conf a bit, as follows:
(dipsy is my servername, internal DNS server)

initial-interval 1;
send host-name "dipsy";
supersede domain-name "bamweb.nl";
prepend domain-name-servers 127.0.0.1;
request subnet-mask,
broadcast-address,
routers,
domain-name,
domain-name-servers,
host-name;

I had configured an alias on my external NIC (xl0), this way I can manage my bridge. To do this type in the following:

To have this at startup edit the /etc/hostname.<interface> (in my case hostname.xl0)

# ifconfig xl0 inet alias 172.19.3.10 netmask 255.255.255.0

$ cat /etc/hostname.xl0

dhcp NONE NONE NONE
inet alias 172.19.3.10 255.255.255.0 NONE
up
rtsol

After this you can save your config also. Otherwise you'll have to connect to your moden with a static IP within the range 172.19.3.x/24