On Sun, Mar 25, 2001 at 12:43:07AM -0300, Rogerio Brito wrote:
> On Mar 24 2001, bert hubert wrote:
> > If someone manages to write a reasonable explanation for the
> > 'onlink' option, I'll put it in the HOWTO ASAP.
>
> As far as I understand it, the situation is as follows:
>
> - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
> Sometimes, you may want to send packets via a machine
> (i.e., a gateway) which is physically connected to your
> network, but to which you don't specifically have a route in
> your kernel routing table.
I'm more confused then ever!
Alexey says this:
A: Yes, in 2.2 the rule that {\em normal} gateway must reside on directly
connected network has not any exceptions. You may tell kernel, that
this particular route is {\em abnormal}:
\begin{verbatim}
ifconfig tunl0 10.0.0.1 netmask 255.255.255.255
ip route add 10.0.0.0/8 via 193.233.7.65 dev tunl0 onlink
\end{verbatim}
Note keyword \verb|onlink|, it is the magic key that orders kernel
not to check for consistency of gateway address.
Probably, after this explanation you have already guessed another method
to cheat kernel:
\begin{verbatim}
ifconfig tunl0 10.0.0.1 netmask 255.255.255.255
route add -host 193.233.7.65 dev tunl0
route add -net 10.0.0.0 netmask 255.0.0.0 gw 193.233.7.65
route del -host 193.233.7.65 dev tunl0
\end{verbatim}
Well, if you like such tricks, nobody may prohibit you to use them.
Only do not forget
that between \verb|route add| and \verb|route del| host 193.233.7.65 is
unreachable.
However, our HOWTO says this:
ip tunnel add netb mode gre remote 172.19.20.21 local 172.16.17.18 ttl 255
ip link set netb up
ip addr add 10.0.1.1 dev netb
ip route add 10.0.2.0/24 dev netb
We don't use onlink - might it be that 'onlink' is only useful for ipip
tunnels?
> Please let me know if this is acceptable. I could write with
> more details (giving a more concrete example), but I'm very
> busy right now. :-(
Once this is cleared up, your text will do fine. Thanks!
Regards,
bert
--
http://www.PowerDNS.com Versatile DNS Services
Trilab The Technology People
'SYN! .. SYN|ACK! .. ACK!' - the mating call of the internet
