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Date: Sun, 14 Dec 2008 14:00:12 +0100
From: Roger Olofsson <240olofsson@telia.com>
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Subject: Canonical way for DHCP->IP->/etc/hosts
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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.

Pre-conditions.
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:

#!/bin/sh

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>

     fi
fi