Mailinglist Archive: opensuse (3605 mails)

[Carl Hartung <suselinux@xxxxxxxxxxxxx>]

On Sunday 04 June 2006 14:00, it clown wrote:
> Is there a way to force your network cards to stay eht0 and
> eth1 with the correct ip addresses?

Hi it clown,

Found this thread in my 'tips' archive:

Jason wrote:
>    I have SuSE linux 9.3 with two NIC's in it.  Which was picked as 
> eth0 and which as eth1 changed sometimes and I needed them to stay the 
> same.  This was solved by setting their names to lan0 and lan1 using 
> the PERSISTENT_NAME option in their configuration files.  However, 
> both NICs are on the same subnet and I need to be able to pick which 
> one is used to communicate with other hosts on the same subnet.  The 
> routing table looks like this:
>
> # route -n
> Kernel IP routing table
> Destination     Gateway         Genmask         Flags Metric Ref    
> Use Iface
> 172.18.88.0     0.0.0.0         255.255.252.0   U     0      0        
> 0 lan0
> 172.18.88.0     0.0.0.0         255.255.252.0   U     0      0        
> 0 lan1
> 127.0.0.0       0.0.0.0         255.0.0.0       U     0      0        
> 0 lo
> 0.0.0.0         172.18.91.254   0.0.0.0         UG    0      0        
> 0 lan0
>
>    With this routing setup, communication with other hosts on the same 
> subnet sometimes goes through lan0 and sometimes through lan1.  I need 
> to make sure it always goes through lan0.  I was able to solve this 
> manually by changing the metric for the route through lan1 as:
>
> # route add -net 172.18.88.0 netmask 255.255.252.0 metric 5 dev lan1
> # route del -net 172.18.88.0 netmask 255.255.252.0 metric 0 dev lan1
> # route -n
> Kernel IP routing table
> Destination     Gateway         Genmask         Flags Metric Ref    
> Use Iface
> 172.18.88.0     0.0.0.0         255.255.252.0   U     0      0        
> 0 lan0
> 172.18.88.0     0.0.0.0         255.255.252.0   U     5      0        
> 0 lan1
> 127.0.0.0       0.0.0.0         255.0.0.0       U     0      0        
> 0 lo
> 0.0.0.0         172.18.91.254   0.0.0.0         UG    0      0        
> 0 lan0
>
>
>    I would like to be able to make this happen automatically though.  
> If I add an entry in the routes file for lan1 with a higher metric, I 
> get multiple routes out lan1, one with a 0 metric and one higher.
>
> # cat /etc/sysconfig/network/routes
> default 172.18.91.254 - lan0
> 172.18.88.0 - 255.255.252.0 lan1 - metric 5
>
> # route -n
> Kernel IP routing table
> Destination     Gateway         Genmask         Flags Metric Ref    
> Use Iface
> 172.18.88.0     0.0.0.0         255.255.252.0   U     0      0        
> 0 lan0
> 172.18.88.0     0.0.0.0         255.255.252.0   U     0      0        
> 0 lan1
> 172.18.88.0     0.0.0.0         255.255.252.0   U     5      0        
> 0 lan1
> 127.0.0.0       0.0.0.0         255.0.0.0       U     0      0        
> 0 lo
> 0.0.0.0         172.18.91.254   0.0.0.0         UG    0      0        
> 0 lan0
>
>
>    I tried putting the metric 5 route in ifroute-lan1 instead of 
> routes but that had no effect.  How do I automatically delete or 
> replace the 0 metric route out lan1?  Is there a better way to do this 
> than what I've tried so far?
>
> Thanks,
>
> Jason 

>     Turns out there were a lot of ways to do this.  The file
> /etc/sysconfig/network/ifcfg.template shows a few variables you can use
> and tells you to look at the man page of ifup and the files
> /etc/sysconfig/network/config,dhcp,wireless for more.  I somehow
> overlooked what I need in the man page and didn't find it in the files
> but read the actual /sbin/ifup script and found the variable
> POST_UP_SCRIPT.  I set it to POST_UP_SCRIPT='scripts/postup-lan1' in the
> config file for lan1, /etc/sysconfig/network/ifcfg-eth-id-mymacaddress
> where the contents of postup-lan1 are:
>
> # cat scripts/postup-lan1
> ifconfig | grep '^lan1' && route del -net 139.78.88.0 netmask
> 255.255.252.0 metric 0 dev lan1
> ifconfig | grep '^lan1' && route add -net 139.78.88.0 netmask
> 255.255.252.0 metric 5 dev lan1
>
>     All is working as desired now.
>
> Jason

hth & regards,

Carl

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