Simple Routing using FC2/3

[Bob Chiodini]

On Sun, 2005-03-06 at 23:53 -0600, Cris Rhea wrote:
> On Sun, Mar 06, 2005 at 11:09:46PM -0600, Les Mikesell wrote:
> > On Sun, 2005-03-06 at 22:06, Todd Wohlwend wrote:
> > > This silly routing thing is driving me buzzonkers.  I did have a typo in my 
> > > first email concerning the gateway address of the LAN PC.  The PC was 
> > > configured correctly.  Here are the correct stats and output.
> > > 
> > > FC3 Soon to be Router Box :  (dns-172.16.176.72)
> > > eth1 - ip-172.16.176.153, snm-255.255.240.0, gw-172.16.176.1
> > > eth0 - ip-192.168.213.254, snm-255.255.255.0, gw-blank
> > > 
> > > PC tied to FC3 eth0 NIC via crossover cable :  (dns-172.16.176.72)
> > > eth0 - ip-192.168.213.253, snm-255.255.255.0, gw-192.168.213.254
> > > 
> > > Router box route command.
> > > [root at FC3-dt ~]# route
> > > Kernel IP routing table
> > > Destination     Gateway         Genmask         Flags Metric Ref    Use 
> > > Iface
> > > 192.168.213.0   *               255.255.255.0   U     0      0        0 eth0
> > > 172.16.176.0    *               255.255.240.0   U     0      0        0 eth1
> > > 169.254.0.0     *               255.255.0.0     U     0      0        0 eth1
> > > default         172.16.176.1    0.0.0.0         UG    0      0        0 eth1
> > > 
> > > /etc/sysctl.conf routing section
> > > # Controls IP packet forwarding
> > > net.ipv4.ip_forward = 1
> > > 
> > > >From the PC, I can ping itself of course, 192.168.213.254, and 
> > > 172.16.176.153.  I cannot ping anything else on the 172 network.  (Note : 
> > > The Router Box can ping all devices in the 172 network)
> > 
> > If you don't NAT, the boxes on the 172 net must have a reason to route
> > the 192.168.213.x addresses back to your router box.   If it isn't
> > their default gateway you need to add a route back in the router that
> > is their default gateway.  If this isn't possible, you should add
> > NAT on the router box you are describing so all of the 192.168.213.x net
> > will appear on the other side as 172.16.178.153.
> > 
> > -- 
> >   Les Mikesell
> >    les at futuresource.com
> 
> IMHO, this isn't about (or related to NAT). This is simple IP routing between
> two private networks. 
> 
> The information above looks fine... There's something missing...
> 
> Do a "cat /proc/sys/net/ipv4/ip_forward" and see what it returns...
> Do an "iptables --list" and see what it returns.
> 
> What Todd is describing above I've done bunches of times. There should be no
> magic in doing this in FC2/3 (or any other Linux/RH version).

Running a routing daemon would probably fix this.  IIRC, zebra is the
daemon.  It used to be routed or gated.  I don't know whether zebra will
route private addresses.  If you want to go beyond you local LANs then
NAT will be required.

Bob...