[TriLUG] Networking questions

[Tom Bryan]

I've configured IP masquerading with ipchains on a RH 7.1 box so that I can 
use the server's modem from any other machine in the house.  I have a few 
questions that I was hoping someone could answer so that I don't have to 
do any more digging today.

1) I now have nameserver entries in /etc/resolv.conf on the client machines 
(all Linux boxes) on my network.  When the server isn't connected to the 
internet, connections within my internal network are taking a long time.  I'd 
like to make each box check /etc/hosts before going to a nameserver, but I 
can't remember how to do that. 

2) I use a laptop at work and home, so I use DHCP to configure its IP address 
on both networks.  I'm not sure which of the dhcpd.conf options need to be 
set so that the laptop can get the correct IP address (the machine with the 
modem) for the default gateway.  Is it the "routers" option?

3) I was a little confused by the IP Masquerading HOWTO.  I have a 2.4.x 
kernel but am still using ipchains.  In testing, it had me run 
echo "1" > /proc/sys/net/ipv4/ip_forward 
echo "1" > /proc/sys/net/ipv4/ip_dynaddr
Right now, I've added those lines to /etc/init.d/ipchains, but I thought that 
there might be a better way to do it on a Red Hat (7.1) system.  

4) The HOWTO also said to 
echo "1" > /proc/sys/net/ipv4/ip_always_defrag
but I don't see an ip_always_defrag file in that directory.  I'm not sure 
what that means, but I would like to defragment all packets coming into my 
network.  

5) The HOWTO made a passing remark about adding 
FORWARD_IPV4=true 
to /etc/sysconfig/network on a 2.2.x kernel.  If I'm using ipchains on a 
2.4.x kernel, does that still apply.  

I could probably test all of these things myself, but the server that 
currently has the modem is also the NFS fileserver. :)  I'm trying to avoid 
unnecessary reboots since I'd then have to shut down my other machines.  

Thanks,
---Tom