Beginner's networking problems

[Tim.Bissell@dresdnerkb.com]

Hi,

I have installed OpenBSD 2.7 off the CDs onto a PC, for use as
a firewall/NAT gateway for my home network to the outside world.

I've been programming on Unix boxes for years, but I'm not very
experienced at admin work.

The PC has an ethernet card (dc0) for talking to the home network,
and a modem for talking to my ISP.  Its IP address on dc0 is
10.0.0.1 (I'm using 10.x.x.x for my home network) and I am using
userland PPP to talk to my isp, with a fixed IP address.

After installation, I enabled IP forwarding and IP filter:

/etc/sysctl.conf:
net.inet.ip.forwarding=1

/etc/rc.conf:
ipfilter=YES
ipnat=YES

For IPF rules I set it to pass all (until I'm ready to
test the firewalling):

/etc/ipf.rules
pass in from any to any
pass out from any to any

/etc/ipnat.rules:
map ppp0 10.0.0.0/8 -> ppp0/32 portmap tcp/udp 1025:60000

my /etc/resolv.conf file contains:
<a blank line>
nameserver 158.152.1.x	(cant remember)
nameserver 158.152.1.x  (ditto, but it's demon.co.uk)

I've written a PPP script to log into my ISP, which works.
I can dial my ISP, and send and receive mail via sendmail,
I can ftp ftp.demon.net, I can use lynx to read (e.g.)
www.sendmail.org so the connection is mostly working.
As root on the box, I can ping internet machines and use
nslookup to get IP addresses, but if I am logged in as
a normal user on the box, and the PPP link is up, any
attempt to ping an external box results in:

ping: cannot resolve x.y.x: Host name lookup failure

Does anyone have any ideas what the problem could be,
or what diagnostic tools I can use to find out?

I've looked at the output of netstat -rn, route show
and ifconfig -a, and I can't see anything that looks
wrong to my untrained eye.

If on another machine on the network, I try and
ping an external IP address (say the IP of ftp.demon.net),
then I get 100% packet loss.  I can see the requests
goind out on the modem (a serial cable debugger with LEDs),
just no flickers on the incoming LEDs.

If anyone has any suggestions or can help, I'd be most
grateful.  To recap, it's a CD OpenBSD 2.7 installation,
ppp to the 'demon' ISP in the UK, and I'm quite happy to
re-install and/or give log files and/or error messages
to anyone who can help.

Thanks in advance,

Tim
--
Work: tim.bissell@dresdnerkb.com  +44 (0)171 4758789
Home: tim@ursidae.demon.co.uk     +44 (0)1480 451022


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