"ip route" shows no default route

Manganus · 12-18-2014, 03:24 AM

[edit: The following is not a SOLVED issue yet, but it turned out that some kind of cache may be responsible. After a couple of hours, the NAS got again connection with the network on the WAN-side of the router, and now it has a default route in its routing table again. Strange!

]

I am scratching my head.

Usually the NAS, that's wired to the 192.168.5.1 router, could ping out of the network. Then, suddenly, it could no longer. (Maybe I'd rebooted the NAS. Maybe. Anyway, I tried a reboot as an early measure to solve the problem. It didn't.) And that's when I discovered that there was no default route in its main routing table.

It seems likely that this lack of default route was the cause that explained why the NAS no more could get connected to the internet (to check timeserver or firmware updates...).

But how can this occur?
And what should I do to fix it?

When connecting to the same router with my linux computer through ethernet, I get:

Code:

$ ip route
192.168.5.0/24 dev eth0  proto kernel  scope link  src 192.168.5.106  metric 1 
$

But when connecting with wifi, there is a default route too:

Code:

$ ip route
default via 192.168.5.1 dev wlan0  proto static 
192.168.5.0/24 dev wlan0  proto kernel  scope link  src 192.168.5.103  metric 9 
$

I don't know if it was like this before.

However, when I checked another NAS (admittedly with an older firmware) connected to an identical router, then its main routing table had more entries:

Code:

# ip route
192.168.4.0/24 dev eth0  proto kernel  scope link  src 192.168.4.100 
127.0.0.0/8 dev lo  scope link 
default via 192.168.4.1 dev eth0 
#

(I maybe should raise this question in the newbie forum instead, since I feel like just a user of Linux (Mint Quiana).
I don't know anything about which programs that are responsible for what. And before today, I hadn't bothered about such things as different routing tables...)

smallpond · 12-18-2014, 04:27 PM

Is it using DHCP? DHCP pushes not only the IP address, but can also push a default route as part of network setup.

For static IP, the default route must be set manually.

Manganus · 12-18-2014, 07:07 PM

Quote:

Originally Posted by smallpond

Is it using DHCP? DHCP pushes not only the IP address, but can also push a default route as part of network setup.

For static IP, the default route must be set manually.

Thank you, smallpond!

Yes, the routers serve as DHCP servers.

Both the dd-wrt routers and the routers with tp-link firmware give similar results:
If the linux laptop connects via wifi, it gets a default route. If it connects with ethernet, there is no default route, and the laptop can reach only ip-adresses in the same sub net.

One or two days before, I'd moved the routers around, and given them new ip-adresses in new sub nets, in order to put the most stable router where continuous function is most crucial.