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Linux RH 9.0 SNAT question

Posted on 2003-10-21
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Last Modified: 2010-04-20
Hi experts,

I'm trying to set up my Linux network for simulation of a small ISP.  
I've enabled the HTTP server successfully and set up iptables for a firewall mechanism.
I'm trying to run a static IP system so I don't have to worry with DHCP, but this yields some other problems.

Things you should know beforehand:
In the iptables file that loads Iptables I have an snat entry at the end which is supposed to do the same as masquerading would for DHCP.  
I'm not recieving anything on the host for an IP address.
I cannot ping the gateway from the host.
HTTP runs correctly.
Although I'm running my network from server to host directly now, I will be incorporating an independant router later on.

Things I want to know:
How do I get the host or the server to pull/give the IP address?  I'm pretty sure I've got everything on the host set up correctly as I've worked with a many XP systems.
What should I have for the gateway on the host side?  Right now I'm using the IP address for the server.  And the DNS entries are the same as my server.


Thanks for any Input as I'm stuck:(
Yoshi
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Question by:yoshi78
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3 Comments
 
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dschwartzer earned 250 total points
ID: 9594261
1) ping doesn't work while http does:
-either iptable drops icmp, or http turns to the different IP. Try other services: telnet, ftp....
2) I'm not an iptables expert (at all), but snat sounds like Static NAT - where you have a 1-to-1 address translation in either direction, unlike the masquerading, which is the Dynamic/Hide NAT - which is used to hide all LAN machines behind the host's single (il)legal address.
3) If you defined static IPs on hosts, they are not going to pull anything from the server (IP). Not unless you define the clients to work with dynamic IPs (DHCP) and define the server to answer DHCP requests.
4) DNS leave for the end. when everything else works, then configure DNS.
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by:yoshi78
ID: 9595801
Thanks for the reply!
Let me clear a few things up:
1)  I can ping from outside the network.  Http serves pages to those intended to receive them.  I can't ping the gateway i set up from hosts inside my local network.

2)snat is for static Ips. I need to know how to set them up on the server.  The client side, I'm extremely familiar with.  Also, I didn't think DHCP was necessary for the server when static ips were used though.  I thought the server specified a range of acceptable ip's it would "look for".  (I'm using a 10.1.1.1 network for the hosts served by eth1, gateway of 255.255.255.0)

3) DNS, I'm pretty sure will use the same numbers the server uses as I have no DNS server inside my LAN.  But, you are right, leave that for the end.

Thanks again for the input,
Yoshi
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Expert Comment

by:S0lar
ID: 9596959
yoshi : please post here your iptables rules.
2) in case of iptables rule SNAT does not mean StaticNAT it means packets' source address replacement - source nat....
[QUOTE]
How do I get the host or the server to pull/give the IP address?  I'm pretty sure I've got everything on the host set up correctly as I've worked with a many XP systems.
[/QUOTE]
You definitely need DHCP to lease ip addresses/other config from server.
3. DNS - piece of cake.
----------
Give us more info, please describe the setup you want to implement.
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