I'm trying to move away from a router/hub and use a Red Hat 7.3 box to route my packets.

I assume that I set up the DHCP server correctly, because hosts get good IP addresses and know the address of the gateway. Hosts also receive the addresses of the DNS servers provided by my DSL ISP correctly.

Strangely, hosts can ping outside IPs, but not corresponding outside names. The Linux server can get to any website fine.

/etc/sysconfig/ipchains:

# Firewall configuration written by lokkit
# Manual customization of this file is not recommended.
# Note: ifup-post will punch the current nameservers through the
# firewall; such entries will *not* be listed here.
:input ACCEPT
:forward ACCEPT
-P forward DENY
-A forward -i ppp0 -s 192.168.0.0/255.255.255.0 -j MASQ
:output ACCEPT
-A input -s 0/0 67:68 -d 0/0 67:68 -p udp -i eth0 -j ACCEPT
-A input -s 0/0 67:68 -d 0/0 67:68 -p udp -i eth1 -j ACCEPT
-A input -s 0/0 -d 0/0 -i lo -j ACCEPT
-A input -p tcp -s 0/0 -d 0/0 0:1023 -y -j REJECT
-A input -p tcp -s 0/0 -d 0/0 2049 -y -j REJECT
-A input -p udp -s 0/0 -d 0/0 0:1023 -j REJECT
-A input -p udp -s 0/0 -d 0/0 2049 -j REJECT
-A input -p tcp -s 0/0 -d 0/0 6000:6009 -y -j REJECT
-A input -p tcp -s 0/0 -d 0/0 7100 -y -j REJECT

Any ideas why hosts don't seem to be able to resolve names correctly?

Do they have DNS adresses configured?

What do you mean?

by ipconfig /all I can tell that they are receiving the correct DNS addresses

Thanks for your time

do you have ip forwarding enabled? type 'echo "1" > /proc/sys/net/ipv4/ip_forward' as root. Also, ensure you have a default route pointing out from your linux box, to your remote ip (next hop) at your ISP.

I have the same problem here : DHCP set up OK (I can ping my LAN's hosts and I can ping the external IP of my gateway.
I tried setting up forwarding servers (i.e. my ISP's DNS) for the BIND server in Webmin, thinking it would take care of the routing. It didn't.
What should my route settings look like if there were a route leading from my box to my ISP's DNS ?

"route" output :
Table de routage IP du noyau
Destination Passerelle Genmask Indic Metric Ref Use Iface
192.168.254.254 * 255.255.255.255 UH 0 0 0 ppp0
192.168.1.0 * 255.255.255.0 U 0 0 0 eth0
192.168.60.0 * 255.255.255.0 U 0 0 0 ADIModem
127.0.0.0 * 255.0.0.0 U 0 0 0 lo
default 192.168.254.254 0.0.0.0 UG 0 0 0 ppp0

Thanks

It depends on the DNS server IP. Usually, it's just a global IP which is covered by the last (default) route entry.

I figured out that problem. The issue was with ipchains. I selected "medium" security when I installed Redhat. If you comment out the tcp and ip lines in your ipchains file, packet forwarding works.

FYI, DNS is completely unrelated to routing.

DNS's main function is to convert domain/hostnames into IP Addresses, that's it. It has nothing to do with the trafficing of drugs...I mean packets.

An exception to this, some may point out, is round robin DNS. I still wouldn't call it true routing though. All it does is assign 2 or more IP addresses to the same hostname, and increments down the list of which IP it gives out.

Hope this helps.

I knew that !
However, for my LAN hosts to browse the web, they need to resolve names into IPs first. I'm using DHCP and I don't know how to set it up for my hosts to get my ISP's DNS addresses. As I said above, I'm using webmin to configure all this, and I have a local DNS on my LAN. Is it necessary ? Can I just go with my ISP's ?
thanks

In your DHCP server config file (maybe /etc/dhcpd.conf) you can specify whatever DNS servers you want to. using the following option and syntax:

option domain-name-servers dns1, dns2, dns, ...;

You don't *need* a local DNS server, but it can make things faster. Instead of going to your ISP to get DNS requests, it just goes local and there's the chance that if you've already been to the site, your local DNS server has it cached.. hence it's faster.