netctl: default route disappears

bcd87 · 2014-11-10 12:37:38

I use netctl to connect to a wireless network that doesn't provide me with a default route.
The default route is added using Routes=() in the netctl profile.
However, after a certain amount of time the route just disappears. I can manually add it again using ip route, upon which everything works again.
The netctl service is running.

Does anyone know what might cause this? I don't see anything weird in the logging.

Leonid.I · 2014-11-10 17:56:08

bcd87 wrote:

I use netctl to connect to a wireless network that doesn't provide me with a default route.
The default route is added using Routes=() in the netctl profile.
However, after a certain amount of time the route just disappears. I can manually add it again using ip route, upon which everything works again.
The netctl service is running.
Does anyone know what might cause this? I don't see anything weird in the logging.

Assuming that you obtain an IP address via DHCP, I guess that at the lease renewal, your dhcp client rewrites your default route with a blank one. If you are using dhcpcd(8), I'd try running it with "-G" in DhcpcdOptions='' (it's undocumented due to whatever reason). If you are using dhclient, read its manpage for an equivalent option. Or better yet, get rid of it

bcd87 · 2014-11-10 18:17:20

Just added -G to my DhcpcdOptions. I'll be able to test again tomorrow. Thanks

Edit: Didn't work. The route is still disappearing.

Last edited by bcd87 (2014-11-11 08:25:59)

bcd87 · 2014-11-13 10:29:45

Right, so I finally figured out what's happening.

The first issue is that I don't get a default route. This is due to a misconfigured DHCP server.
RFC3442 states that when option 121 (Classless Static Route) is used, the DHCP client must ignore the Router option:

If the DHCP server returns both a Classless Static Routes option and
a Router option, the DHCP client MUST ignore the Router option.

I used DhcpcdOptions='-O 121' to ignore option 121, and verified that a default route was now automatically added without having to use netctl's Routes=('') option.

That still leaves the issue of the disappearing route. Apparently there are some issues with my network driver that causes a lost carrier a few times a day. When that happens all routes get removed, when the carrier is acquired again (in some cases only 4 seconds later), the routes get setup according to the DHCP options, but the routes in netctl are ignored.
This seems like a bug to me.

Edit: Created a bug-report https://bugs.archlinux.org/task/42772

Last edited by bcd87 (2014-11-13 11:18:09)

Leonid.I · 2014-11-15 02:26:43

I'm glad that you found a workaround... but why do think this is a bug in netctl? AFAIU from reading /usr/lib/network/ip, it sets a static route after a call to dhcpcd. So, when the lease is renewed, the route is overwritten by dhcpcd. I don't think that your wifi issues are related to the TCP/IP problems. Are you using netctl-auto with wpa_actiond? If not, netctl/dhcpcd won't even notice that your carrier disappeared.

Arch Linux

#1 2014-11-10 12:37:38

netctl: default route disappears

#2 2014-11-10 17:56:08

Re: netctl: default route disappears

#3 2014-11-10 18:17:20

Re: netctl: default route disappears

#4 2014-11-13 10:29:45

Re: netctl: default route disappears

#5 2014-11-15 02:26:43

Re: netctl: default route disappears

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