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
