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

[Roger Olofsson]

Greg Larkin skrev:
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> Roger Olofsson wrote:
>>
>> Jeff Laine skrev:
>>> On Sun, Dec 14, 2008 at 02:00:12PM +0100, Roger Olofsson wrote:
>>>> 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
>>>>
>>> Hello. I think pf can handle with dhcp updates on interfaces pretty well.
>>> If only I get your question right.
>>>
>>>
> 
>> Hi Jeff and thank you for your reply,
>>
>> Yes, I know that pf will handle interfaces just fine, the question was
>> not specific to pf though but more around dhclient, dhclient-script and
>> the part of dhclient-script that calls the undocumented
>> dhclient-exit-hooks.
>>
>> It might be handy to have the external IP assigned to a hostname - not
>> only for pf.
>>
>> /R
> 
> 
> Hi Roger,
> 
> I wrote a blog post about automatically configuring /etc/hosts with a
> DHCP dynamic IP address earlier this year:
> http://blog.sourcehosting.net/tag/dhcp/.  You can download a ZIP file
> with the dhclient-exit-hook script in it near the bottom of the page.
> 
> In my case, I also wrote some commands to update the Apache httpd.conf
> file with the correct ServerName directive.  You can easily remove that
> from the script if you don't need it.
> 
> If you need any assistance, let me know.
> 
> Regards,
> Greg
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Hello Greg,

Thank you very much. I guess this is the canonical way of doing it.

/R