How to make linux retry to bring up eth0 if failiure

Gramphos · 11-18-2003, 03:05 PM

I have a computer that I sometimes wants to be able to access via network, especially on times when I'm on another location than the computer.

The problem is that the computerlocation sometimes gets powercuts and when the power is restored my system boots faster than the DHCP server and router and the eth0 bring up will fail.

Is there any way to make the computer retyr every 5 minutes if the network is down?

mi6alec · 11-18-2003, 04:16 PM

i don't know about every five minutes, but typing at a command line
ifup eth0 or ifconfig eth0 up

will bring it back up. this may need to be root?

Gramphos · 11-19-2003, 02:54 AM

Well ther problem is that I won't be able to do commands unless the net is up and I can log in with SSH, so I need a way to ensure that it is up.

michaelk · 11-19-2003, 07:33 AM

Do you have to use DHCP? Just configure your eth0 for a static IP address.
Stick an UPS on the DCHP server and router.

Yes, you could write a script to try configuring eth0 with a fixed interval.

/bin/bash · 11-19-2003, 09:14 AM

In Mandrake I would restart my network by doing this:
service network restart
So I could write a script and run it from /etc/rc.d/rc.local that would try to ping my GATEWAY and until it got a good ping it would sleep then restart then ping then try again.

That script would look something like this:

Code:

#!/bin/bash
GATEWAY=192.168.0.1
PING="100%"
until [ "$PING" = "0%" ]
    do
    sleep 30
    echo "Trying to start network..."
    service network restart
    PING=`ping -c1 -w2 $GATEWAY 2>/dev/null|grep pack|awk '{print $6}'`
done

The output of the script looks like this.

Code:

./startnet
Trying to start network...
Shutting down interface eth0:                                   [ COOL ]
Shutting down loopback interface:                               [ COOL ]
Setting network parameters:                                     [ COOL ]
Bringing up loopback interface:                                 [ COOL ]
Bringing up interface eth0:  Can't find a dhcp client
                                                                [BUMMER]
Trying to start network...
Shutting down loopback interface:                               [ COOL ]
Setting network parameters:                                     [ COOL ]
Bringing up loopback interface:                                 [ COOL ]
Bringing up interface eth0:  Can't find a dhcp client
                                                                [BUMMER]
Trying to start network...
Shutting down loopback interface:                               [ COOL ]
Setting network parameters:                                     [ COOL ]
Bringing up loopback interface:                                 [ COOL ]
Bringing up interface eth0:                                     [ COOL ]

<edit> Of course you may need to change GATEWAY and the sleep value.
Another thing is you would want to ping the GATEWAY first and only run the script if the network is down, otherwise you have a big long delay in your bootup. I guess that could be done in the script too. Let me see.

Code:

#!/bin/bash
GATEWAY=192.168.0.1
PING=`ping -c1 -w2 $GATEWAY 2>/dev/null|grep pack|awk '{print $6}'`
until [ "$PING" = "0%" ]
    do
    sleep 30
    echo "Trying to start network..."
    service network restart
    PING=`ping -c1 -w2 $GATEWAY 2>/dev/null|grep pack|awk '{print $6}'`
done

Yes the above works better than the really far above.