Re: modem / pon / serial problems
On Tue, Feb 04, 2003 at 10:50:43PM +0000, Pigeon wrote:
> So: the main box is 192.168.1.1, the modem box is 192.168.1.2. I add
> "gateway 192.168.1.2" to /etc/network/interfaces on the main box and
> run /etc/init.d/networking restart.
>
> On the modem box I do
> echo 1 > /proc/sys/net/ipv4/ip_forward
> ipchains -A forward -s 192.168.1.1/32 -d 0.0.0.0/0 -j ACCEPT -b
> ipchains -P forward ACCEPT
> pon ukonline
> ping 195.40.1.36 (this is a ukonline DNS server)
> ... and it works.
>
> I go back to the main box and try and ping the same address, and
> nothing happens.
>
Different approach. Now on the modem box I do:
modprobe ipt_MASQUERADE
iptables -F
iptables -t nat -F
iptables -t mangle -F
iptables -t nat -A POSTROUTING -o ppp0 -j MASQUERADE
echo 1 > /proc/sys/net/ipv4/ip_forward
And from the main box, I can get through the modem box and out onto
the net. I can ping 195.40.1.36 from the main box and it works.
The problem now is DNS. My ISP uses dynamic DNS, so I am used to
having ppp rewrite my /etc/resolv.conf every time I connect. Now, of
course, the modem box is doing the connecting, so the main box's
/etc/resolv.conf does not get updated. The ISP seems to be giving me
any two out of three nameservers, so I could fudge it by putting all
three in the main box's /etc/resolv.conf, but I'd rather have it
updating automatically like it's supposed to.
So I have resorted to a VILE HACK. The main box exports its /etc via
NFS to the modem box. A script in the modem box's /etc/ppp/ip-up.d
then copies the modem box's newly updated /etc/resolv.conf across to
the main box whenever I connect.
I'm sure there must be a less vile method of doing this... what is it?
Pigeon
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