Re: tlug: Q: Mini-LAN with PPP

[Manuel Chakravarty <chak@example.com>]

Stephen J. Turnbull wrote,

> >>>>> "ASH" == Andrew S Howell <andy@example.com> writes:
> 
> >>>>> "Manuel" == Manuel Chakravarty <chak@example.com> writes:
> 
>     Manuel> Hi!  Yesterday I played a bit with PPP and tried to set up
>     Manuel> a kind of mini-LAN between two Linux machine (neither of
> 
> I assume you mean using the serial interface with a null-model cable?

Yep.

>     ASH> The "network not reachable" is saying that there isn't an
>     ASH> interface over which to route packets to your destination.
> 
>     ASH> To set a default route do:
> 
>     ASH> 	route add default gw ppp-ip-addres
> 
> PPP should be doing that automatically.  (On second thought, that
> depends on the PPP package you're using.  Debian 1.3 certainly does,
> though.)  Furthermore, as far as I know `ping' gets its routing
> information from the same place as any other IP program.  Finally, as
> long as there is a host-to-host route in place, a two-host LAN using
> PPP should not need any network routing information other than that
> provided automatically by PPP.
> 
> I would modify that to 
> 
> 	       route add -host REMOTE-IP dev INTERFACE
>              route add default gw REMOTE-IP
> 
> where things in caps are variables.  INTERFACE should be `ppp0'.  It
> probably doesn't need to be specified.

Usually, you can advice the `pppd' to add a default route
using the option `defaultroute'.  I specified this option
and it doesn't help anything.  But, I am not sure what
exactly `pppd' does when given this option (I am mean which
routing commands it issues -- this also not specified in
detail in the man page).  So, I'll try your commands and
check whether they change anything.

The PPP-HOWTO, in the section ``27.  Using PPP across a null
modem (direct serial) connection'' says,

  pppd -detach crtscts lock <local IP>:<remote IP> /dev/cua4 38400 &

  This will bring up the link - but as yet you have no routing
  specified. You can test the link by pinging to and fro to each
  machine.

This is the part that works. Latter the HOWTO says, 

  So on the Ethernet equipped machine, the pppd command would be

  pppd -detach crtscts lock proxyarp <local IP>:<remote IP> /dev/cua4 38400 &

  and on the other machine

  pppd -detach crtscts lock defaultroute <local IP>:<remote IP> /dev/cua4 38400 &

As I don't have an Ethernet, I thought that maybe issuing
the second command on both machines helps (thereby
establishing the default route).  But actually, this didn't
change anything.

I'll try your commands and get the output of `ifconfig' and
`netstat' (the machines are at home).  So far, many thanks
for your suggestions and comments :-)

Cheers,

Manuel


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