RE: [LARTC] I don't believe all this advanced routing stuff is re

[Greg Scott <GregScott@InfraSupportEtc.com>]

I'm an idiot!

modprobe ip_gre

does the trick.

- Greg Scott


-----Original Message-----
From: Greg Scott [mailto:GregScott@InfraSupportEtc.com]
Sent: Thursday, November 01, 2001 10:18 PM
To: lartc@mailman.ds9a.nl
Subject: [LARTC] I don't believe all this advanced routing stuff is
real!


I'll bet somebody, somewhere knows how answer this.  I am running Red Hat
Linux v7.1, which is based on kernel 2.4.2-2.  

I went to this URL:

	
http://ds9a.nl/2.4Routing/HOWTO/cvs/2.4routing/output/2.4routing-5.html

As I understand things, this is the more or less official HOWTO for the
advanced routing stuff.

Well - how come none of it works???

In particular, the section about GRE tunneling gives some very specific
directions about the commands needed to set all of it up.  Here is a direct
quote:

Let's say you have 3 networks: Internal networks A and B, and intermediate
network C (or let's say, Internet). 
So we have network A: 
	network 10.0.1.0
	netmask 255.255.255.0
	router  10.0.1.1
The router has address 172.16.17.18 on network C. Let's call this network
neta (ok, hardly original) 
and network B: 
	network 10.0.2.0
	netmask 255.255.255.0
	router  10.0.2.1
The router has address 172.19.20.21 on network C. Let's call this network
netb (still not original) 
As far as network C is concerned, we assume that it will pass any packet
sent from A to B and vice versa. How and why, we do not care. 
On the router of network A, you do the following: 
	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


Ok, wonderful.  I did that and here is the result:

# /sbin/ip tunnel add netb mode gre remote nnn.qqq.228.33 local
xxx.yyy.172.162 ttl 255
ioctl: No such device

Huh?  What's going on here?  So I tried a couple other experiments: 

# /sbin/ip tunnel add netb
cannot determine tunnel mode (ipip, gre or sit)

Fair enough.  Let's add some more:

# /sbin/ip tunnel add netb mode gre
ioctl: No such device

Now I'm really confused.  Maybe the online help gives me a clue:

# /sbin/ip help 
Usage: ip [ OPTIONS ] OBJECT { COMMAND | help }
where  OBJECT := { link | addr | route | rule | neigh | tunnel |
                   maddr | mroute | monitor }
       OPTIONS := { -V[ersion] | -s[tatistics] | -r[esolve] |
                    -f[amily] { inet | inet6 | ipx | dnet | link } |
-o[neline]}

So let's try a few things:

# /sbin/ip -V
ip utility, iproute2-ss000305

This seemed to work as advertised.


# /sbin/ip -s
Usage: ip [ OPTIONS ] OBJECT { COMMAND | help }
where  OBJECT := { link | addr | route | rule | neigh | tunnel |
                   maddr | mroute | monitor }
       OPTIONS := { -V[ersion] | -s[tatistics] | -r[esolve] |
                    -f[amily] { inet | inet6 | ipx | dnet | link } |
-o[neline]}
# /sbin/ip -r
Usage: ip [ OPTIONS ] OBJECT { COMMAND | help }
where  OBJECT := { link | addr | route | rule | neigh | tunnel |
                   maddr | mroute | monitor }
       OPTIONS := { -V[ersion] | -s[tatistics] | -r[esolve] |
                    -f[amily] { inet | inet6 | ipx | dnet | link } |
-o[neline]}

So -V does what the online help says it does, but -s and -r generate some
kind of syntax error.

What am I missing?  Should I be modprobing some module someplace?  If so,
what?  How do I tell what modules are available and what they do?  Or is all
this advanced routing stuff not ready for use yet?

- Greg Scott

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