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Old 07-01-2004, 01:21 AM   #1
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Routing to switch

My problem is practially identical to Entropius' but, unfortunately, there was no resolution offered in that thread. I too feel like an idiot

With ppp0 down and eth0 up, I can connect to the router/switch/WAP fine via (configured using DHCP). With ppp0 up and eth0 down, I can connect to my ISP and use the internet. With both interfaces up, I can't do anything. I can't talk to the router and domains will not resolve.

This is the routing table by default when both interfaces are up:
Destination     Gateway         Genmask         Flags Metric Ref    Use Iface   *      UH    0      0        0 ppp0     *        U     0      0        0 eth0
default         UG    0      0        0 eth0
default         UG    0      0        0 ppp0
The IP on ppp0 is updated automatically whenever I dial in to my ISP. 'route del default dev eth0' lets me resolve domains but I can't get to How can I add a route to it?

Any help would be much appreciated
Old 07-01-2004, 01:45 AM   #2
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Re: Routing to switch

Originally posted by thinkninja

Destination     Gateway         Genmask         Flags Metric Ref    Use Iface   *      UH    0      0        0 ppp0     *        U     0      0        0 eth0
default         UG    0      0        0 eth0
default         UG    0      0        0 ppp0
this routing table seems ok instead of loopback. where is it? i think if u add loopback, your trouble can be solved.
Old 07-01-2004, 01:49 AM   #3
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Well it's not going to be workable if you have two default routes each with an equal metric. The poor kernel will probably try to split packets evenly between them, or something ridiculous like that. You should alter your netstart scripts so that if-up'ing eth0 does not add a default gateway.

As for the WAP, you don't mention what subnet it's on. I'm assuming it's not on, because you already have a route to that pointing to the local ethernet segment. Deleting the default route won't destroy the route to 192.168/24. Find out what subnet your wireless clients are on and have that added when eth0 is brought up. You just want to do a route add for the -net of whatever the WAP is on and use a gw of
Old 07-01-2004, 12:22 PM   #4
Registered: Oct 2003
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There's no need for a gateway on any network unless you are trying to get to another ip scheme.

You need a default gw to tell you computer how to get to any network that is not otherwise stated in your route table, or if you have multiple pipes to the internet.

I'd check you DHCP server and remove the default gateway offer from its config.

You could also just address your ethernet interface statically. That would also solve the problem.

You state that once you do a 'route del default dev eth0' you can not get to The only entry you need in your routing table to get to that address is what is already in your list: * U 0 0 0 eth0

Old 07-01-2004, 12:45 PM   #5
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Trying just eth0:
fire:/home/ninja# ifup eth0
sit0: unknown hardware address type 776
sit0: unknown hardware address type 776
Listening on LPF/eth0/00:50:8d:f9:44:f0
Sending on   LPF/eth0/00:50:8d:f9:44:f0
Sending on   Socket/fallback/fallback-net
DHCPREQUEST on eth0 to port 67
DHCPREQUEST on eth0 to port 67
DHCPDISCOVER on eth0 to port 67 interval 6
DHCPREQUEST on eth0 to port 67
bound to -- renewal in 129600 seconds.
fire:/home/ninja# route
Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref    Use Iface     *        U     0      0        0 eth0
default         UG    0      0        0 eth0
Okay, I'm making progress. I can't connect to the router ( at all now, and yes, I have pushed the reset button + plus power-cycled it. I also tried deleting the route to and re-adding one to Probably a stupid idea.

Chort, I knew (even though I readily admit I know nothing about is patently obvious) that having two default routes just wasn't going to work. I couldn't connect to anything on the internet like that until I did 'route del default dev eth0'.

Regarding WAP, I have no wireless clients, nor is anything else connected to the switch...yet. So that's an issue for another day. I am, however, super keen to reconnect to the router itself with a view to attempting further configuration. As it stands, I can't even ping it.

I've reset it again, disconnected the cable, and turned it off while I take a shower. This is making me hot and bothered.
Old 07-01-2004, 04:11 PM   #6
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kernel always applies first match in routing table

so in caseDestination Gateway Genmask Flags Metric Ref Use Iface * UH 0 0 0 ppp0 * U 0 0 0 eth0
default UG 0 0 0 eth0
default UG 0 0 ppp0 is your default gw.

simply just do
route del default gw
before dialing or after dialing.


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