How does ip masquerading work (overview)?

[gaf at blu.org (Jerry Feldman)]

I don't know Red Hat's config that well, but it sounds like your routine 
table.

Check your routing table, using the netstat -nr command.

You should have at least 3 entries:
Destination     Gateway         Genmask         Flags   MSS Window  irtt 
Iface
192.168.0.0     0.0.0.0         255.255.255.0      U          0         0   
       0   eth0
127.0.0.0         0.0.0.0         255.0.0.0             U          0        
0          0   lo
0.0.0.0           192.168.0.1     0.0.0.0             UG         0         
0          0   eth0
In my case, I have one NIC. The lo interface is for the local host. The 
0.0.0.0 entry is the default route. The gateway is normally a router on the 
network. You should have one entry for the local net. In my case, 
192.168.0.0 is my local net, which is set up as a class c by the mask 
255.255.255.0, so anything for 192.168.0.1 to 192.168.0.254 will go out on 
that interface.  You can use the route command to change the table.
route add -net 192.168.1 eth1 would add an entry on eth1 for net 192.168.1. 
Use the route command to set up your touring table for testing. Then add 
those entries to your static routes 192.168.0. You can use the netconf 
command to set your routing table on Red Hat.



gaf at gaf:~ >
   
"kgleason at mail.ma.ultranet.com" wrote:
> Yep, this is at Mount Idee. I have a private network running 10M connecting t
> o another (college) net running 100M. For the time being, don't plan to upgra
> de to faster ethernet so I'm working with what I have. Seems like netconfig d
> oesn't get into changing eth0. When I get into Control Panel I can click on K
> ernel icon and delete and change...but didn't want to do this if there was a 
> more accepted way.
> The other method is uninstalling the 100M Nic card, booting and having 10M ni
> c card recognize as eth0, and reinstalling the 100M card later. 
> Either way, I can't seem to ping the internal network from the router (set to
>  a static IP number)...and I can't ping the internal machine (192.158.1.x) fr
> om the static address. I can ping internal nodes OK. I feel I'm missing somet
> hing more fundamental than eth0 and eth1.
> 
> [I keep thinking of Paul Newman's Cool Hand Luke line to the warden...I think
>  we have a problem trying to communicate.) 
> 
> Original Message:
> -----------------
> From: Jerry Feldman gaf at blu.org
> Date: Mon, 12 Mar 2001 11:31:19 -0500
> To: discuss at blu.org
> Subject: Re: How does ip masquerading work (overview)?
> 
> 
> Why do you want the outside world to connect to the 100M board? If you 
> are connected to a cable modem, you are limited to 10M or below 
> depending on the service. However, if you are at Mount Ida, then this is a 
> bit different. In any case I assume that you are doing this on Red Hat, 
> which has a different interface to IP Masq.
> On 12 Mar 2001, at 9:43, Kevin M. Gleason wrote:
> 
> > I assume that eth0 is the default for the internal network, is the other
> > (eth1 or whatever) assumed to be the outside world?
> > I have my 10baseT card set up for eth1 and 100baseT set for eth0. If
> > line one is correct how can I change it so the internal network (running
> > 10 M) will see the 10 M side of my Linux box (and the outside world will
> > see me as a 100 M connection?
> 
> Jerry Feldman <gaf at blu.org>
> Associate Director
> Boston Linux and Unix user group
> http://www.blu.org
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-- 
Jerry Feldman <gaf at blu.org>
Boston Linux and Unix user group
http://www.blu.org


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