What you could do is to create a crontab with the following bash script
--start---
#!/bin/bash
NEWIP=`host klintan.cjb.net | awk '{print $4}'`
if [ -f /etc/current_ip ]
then
OLDIP=`cat /etc/current_ip`
else
# 1st time run
OLDIP="255.255.255.255/32"
fi
if [ "$NEWIP" != "$OLDIP" ]
then
RULENUM=`iptables -L INPUT --line-numbers | grep "$OLDIP" | grep
"tcp dpt:domain" | awk '{print $1'}`
if [ -z "$RULENUM" ]
then
iptables -A INPUT -p tcp -s $NEWIP --dport 53 -j ACCEPT
else
iptables -R INPUT $RULENUM -p tcp -s $NEWIP --dport 53
-j ACCEPT
fi
echo $NEWIP > /etc/current_ip
fi
--end---
But I'm sure that there are other (and better) ways
/Klintan
> -----Original Message-----
> From: netfilter-admin@xxxxxxxxxxxxxxxxxxx
> [mailto:netfilter-admin@xxxxxxxxxxxxxxxxxxx] On Behalf Of
> bill davidsen
> Sent: Tuesday, April 22, 2003 6:05 PM
> To: netfilter@xxxxxxxxxxxxxxxxxxx
> Subject: Re: host names and IPs
>
>
> In article <003301c305a1$c04ab1a0$0500a8c0@xxxxxxxxxxx>,
> Florian Effenberger <floeff@xxxxxxxx> wrote:
>
> | I'm on Linux 2.4.20 with iptables 1.2.7a. I have a syntax
> as follows:
> |
> | ===
> | iptables -A INPUT -p tcp -s www.myhostname.com --dport 53 -j ACCEPT
> | ===
>
> What is it you're trying to do here? A packet with your
> source address would be going through the OUTPUT table, no?
> An INPUT packet with your own IP would be spoofed. Are you
> trying to accept DNS requests from yourself, in tcp (instead
> of normal udp) mode?
>
> | Now it seems that www.myhostname.com is resolved only the
> first time
> | the rule is set and that a fixed IP address is stored.
> |
> | However, www.myhostname.com has a dynamically assigned
> address and I
> | would like to have iptables resolve the IP address everytime.
> |
> | Is that possible? If yes, how? Or will it produce too much load?
>
> There are several ways to re-resolve it, but I'm not clear on
> why you don't just specify by interface.
>
> How about some clarification on what you're trying to do,
> rather than how you want to do it?
> --
> bill davidsen <davidsen@xxxxxxx>
> CTO, TMR Associates, Inc
> Doing interesting things with little computers since 1979.
>
>
