Red Hat Bugzilla – Bug 477963
NetworkManager sets up wrong routing for system config
Last modified: 2009-03-09 16:44:13 EDT
When I upgraded to Fedora 10, it seems NM grew the ability to read sysconfig stuff even for non-DHCP configs. Unfortunately it somehow messed up the routing.
E.g. I have configured address 10.23.1.2, netmask 255.255.255.248. NM added the correct local and default route, except for the fact that it configured metric 1 on the local route. This is of course a bit funky as that means that there is a higher metric to the local gateway than to everything beyond it.
The kernel responded by considering everything to be locally connected. So trying to reach e.g. 22.214.171.124 resulted in "No route to host" as it couldn't find anything responding to the ARP request.
This is a production machine so I remove NM in order to get a working system, but you should be able to easily reproduce it.
Can you post your ifcfg files? The local routes are "scope link" and in practice I am not having the issue you describe on several systems with statically configured ifcfg addressing. I haven't specifically tried such a large netmask, though.
Sure. Here's the config from one of the machines:
My routing table with this ifcfg:
Kernel IP routing table
Destination Gateway Genmask Flags Metric Ref Use Iface
10.23.1.16 0.0.0.0 255.255.255.248 U 1 0 0 eth0
192.168.1.0 0.0.0.0 255.255.255.0 U 2 0 0 eth2
0.0.0.0 192.168.1.1 0.0.0.0 UG 0 0 0 eth2
Obviously I have wifi connected right now too, and since the ifcfg above was not specified with a gateway, it won't get the default route. Thus, all my traffic for !LAN goes out through eth2 (wifi) correctly.
NM will assign lower routing metrics to more "preferred" devices; maybe that's not quite fine-grained enough. Ethernet > Wifi > GSM > CDMA at the moment; thus as you can see eth0 (ethernet) got a metric of 1, and eth2 (wifi) got a metric of 2.
Does your problem still happen with NetworkManager-0.7.0-2.git20090207.fc10 from f10 updates-testing? That fixes a few odd issues with ifcfg file parsing.
I was probably a bit hasty attributing this to the metric, but it was the only odd thing I could see.
The problem is still present with NetworkManager-0.7.0.97-5.git20090220.fc10.
The symptoms are the same. Everything looks peachy except for the fact that the kernel decides that everything is locally connected.
What is the kernel looking at except the routing table when it decides which IP address it needs to resolve to a MAC address to send out a packet?
Ok, I've spotted the problem. NM sets the wrong gateway. I have 10.23.1.17 configured as GATEWAY in /etc/sysconfig/network, but NM sets 10.23.1.18 (the machine itself) as the gateway. This is what's screwing things up.
Could it be a miscalculation based on the very small net?
(In reply to comment #5)
> Ok, I've spotted the problem. NM sets the wrong gateway. I have 10.23.1.17
> configured as GATEWAY in /etc/sysconfig/network, but NM sets 10.23.1.18 (the
> machine itself) as the gateway. This is what's screwing things up.
> Could it be a miscalculation based on the very small net?
hmm, can you post the ifcfg file for that device? I'll try to reproduce it.
This bug should have been fixed in 0.7.0-2.git20090207:
* Sat Feb 07 2009 Dan Williams <firstname.lastname@example.org> - 1:0.7.0-2.git20090207
- ifcfg-rh: Fix issue with wrong gateway for system connections (rh #476089)
but I only tested with GATEWAY in /etc/sysconfig/network-scripts/ifcfg-ethX. Why are you setting the gateway in /etc/sysconfig/network directly?
(In reply to comment #7)
> This bug should have been fixed in 0.7.0-2.git20090207:
> * Sat Feb 07 2009 Dan Williams <email@example.com> - 1:0.7.0-2.git20090207
> - ifcfg-rh: Fix issue with wrong gateway for system connections (rh #476089)
> but I only tested with GATEWAY in /etc/sysconfig/network-scripts/ifcfg-ethX.
> Why are you setting the gateway in /etc/sysconfig/network directly?
Old habit I guess. Also, the default gateway is a global setting, even though it's tied to a specific device, so it has always made sense to have it there. The initscripts people seem to agree as GATEWAY is documented for /etc/sysconfig/network but only briefly listed for ifcfg-*.
(In reply to comment #6)
> hmm, can you post the ifcfg file for that device? I'll try to reproduce it.
See earlier comment. Just add GATEWAY to /etc/sysconfig/network and you should be all set.
Adding GATEWAY to /etc/sysconfig/network overrides *all* connection gateways; while setting GATEWAY in the ifcfg file itself would only apply to that specific connection (ie, to override DHCP-returned gateway just for that device, as opposed to overriding gateway for wlan0 *and* eth0 both).
NM will use GATEWAY from the ifcfg file first, and if its not set there, check /etc/sysconfig/network for the gateway. If no gateway exists in the ifcfg file, but GATEWAY does exist in /etc/sysconfig/network, and NM isn't using that global gateway for all connections, then it's a bug in NM.
This bug has been triaged
Fedora Bugzappers volunteer triage team
It has been solved as well. I'm just waiting for Dan to push the update. :)
Should have been pushed already; please reopen if for some reason 0.7.0.99-1 doesn't help.