[uClibc] Offtopic: questions about restore linux route tables

Zhuang Yuyao ihollo at tom.com
Mon Jul 4 09:23:22 UTC 2005


Hi,

Sorry for posting an offtopic question to this mail-list, but I have spent a lot of time in searching the web/usergroup but found no answer.  So I think since I am already in this mail-list and here are many many *nix gurus working for embedded system also in this list, maybe this question is trivial to you guys but your answer will be great help to me.

I am working on an embedded system using linux as its OS. User can access this system through web browser, creat/modify/delete/apply static routes and bring up/down network interfaces. The question is when user bring down a network interface (eth*), the static route related to this interface is automatically removed by linux kernel.
i.e.
#ip route add default via 192.168.1.4 dev eth1
#ip route show dev eth1
192.168.1.0/24  proto kernel  scope link  src 192.168.1.5
default via 192.168.1.4
#ifconfig eth1 down
#ip route show dev eth1
***display nothing***

If I bring this interface up again:
#ifconfig eth1 192.168.1.5
#ip route show dev eth1
192.168.1.0/24  proto kernel  scope link  src 192.168.1.5
**The previous route "default via 192.168.1.4" disappeared. I have to add it manual again!**

On the contrary, iptables accepts unknown devices and takes effect when such an interface is available.

The question is: Is it possible to keep the route even the interface is unavailible until user EXPLICITLY deleted it? just as the iptables doing. Or, is there an elegant way to solve such a problem.

Sorry again for this offtopic question. Thanks very much.

        Zhuang Yuyao
        ihollo at tom.com
          2005-07-04


More information about the uClibc mailing list