Hello,
antonio.dibacco a écrit :
I have an ethernet (eth1) without any assigned ip, nevertheless I would
like to route through this IF but issueing the following command gives
an error:
route add -net 192.168.1.0 dev eth1
When I type this command I get an error because 192.168.1.0 is not a
subnet, I must add a mask or prefix length, for instance :
route add -net 192.168.1.0/24 dev eth1
If the same IF has an address the command will be correctly executed.
Why?
The interface has to be up and bound to IPv4. You can check this when
directory /proc/sys/net/ipv4/conf/eth1 exists. To force this without
assigning an address to the interface, just execute the following command :
ifconfig eth1 0.0.0.0 up
The default source address used in locally generated packets will be
chosen among addresses assigned to other interfaces. You can assign it
statically creating the route with 'ip' instead of 'route' :
ip route add 192.168.1.0/24 dev eth1 src $LOCAL_IP
where $LOCAL_IP is a local address assigned to any interface but the
loopback.
Note there are possible issues regarding routing and ARP if you expect
to receive IPv4 traffic on eth1.
- Routing : hosts on the network reachable on eth1 must have appropriate
route(s) to the box addresse(s).
- ARP : your box must accept and reply to ARP requests about any local
address received on eth1. For this, make sure the kernel parameters
arp_filter, arp_announce and arp_ignore in /proc/sys/net/ipv4/conf/eth1
have appropriate value (default values 0 should be fine). Or you can add
static ARP entries on the hosts reachable on eth1.
PS: Any feedback about my reply to your previous question ?
