Canonical way for DHCP->IP->/etc/hosts

Roger Olofsson 240olofsson at
Sun Dec 14 05:00:15 PST 2008

Dear mailing list,

I am sorry if this question has been asked over and over again - however 
the htdig search interface for the lists is somewhat shaky and gives 
referrer errors for me.

Dualhomed firewalled FreeBSD7.1. One nic is LAN and the other dynamical 
IP from ISP.

Question: What is the canonical way for catching the IP address from a 
DHCP assigned nic (from ISP that doesn't set hostname) and put the IP 
into /etc/hosts with a hostname?

Reason for asking
Firewall rules needs refreshing after new IP

Possible answers:
Create dhcp-exit-hooks (undocumented?) in /etc like so:


if [ ! -z "$new_ip_address" ]; then
     IP=`ifconfig WAN | grep 'inet' | grep -v 'inet6' | cut -f 2 -d ' '`
     if [ ! -z "$IP" ]; then
         echo "$IP	wan.local.domain wan" >> /etc/hosts

	<refresh firewall rules here>


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