Re: DHCP renewal changes routing table



On Do, 2015-06-04 at 04:55 -0600, Nicolas Bock wrote:
Hi,

When I run the Juniper Network Connect client (ncsvc) it terminates 
every time the DHCP license is renewed. The log files of ncsvc are 
unfortunately rather cryptic, but it appears as if the DHCP renewal 
leads to a change in the routing table which triggers a "rmon.error" 
in ncsvc which then tears down the VPN tunnel. Using timestamps the 
following two events correlate:

20150603133456.514649 ncsvc[p6870.t6870] rmon.error Route to 
destination 192.168.1.1 is missing mask 255.255.255.255 with gw 
0.0.0.0, metric 1, if_id 0, disconnecting (routemon.cpp:628)

which coincides with the following journal entries:

Jun 03 13:34:55.454967 host NetworkManager[1805]: address 
192.168.1.16
Jun 03 13:34:55.454985 host NetworkManager[1805]: plen 24
Jun 03 13:34:55.454990 host NetworkManager[1805]: expires in 300 
seconds
Jun 03 13:34:55.455026 host NetworkManager[1805]: gateway 192.168.1.1
Jun 03 13:34:55.455035 host NetworkManager[1805]: nameserver 
'192.168.1.1'
Jun 03 13:34:55.455210 host NetworkManager[1805]: (wlp6s0): DHCPv4 
state changed bound -> bound
Jun 03 13:34:55.456679 host dbus[1799]: [system] Activating via 
systemd: service name='org.freedesktop.nm_dispatcher' unit='dbus
-org.freedesktop.nm-dispatcher.service'
Jun 03 13:34:55.461372 host dbus[1799]: [system] Successfully 
activated service 'org.freedesktop.nm_dispatcher'
Jun 03 13:34:55.462021 host nm-dispatcher[8295]: Dispatching action 
'dhcp4-change' for wlp6s0
Jun 03 13:34:56.514958 host systemd-networkd[1803]: tun0 : lost 
carrier

Besides the ncsvc error listed above I sometimes also see this one:

20150603132151.174661 ncsvc[p6870.t6870] rmon.error Unauthorized new 
route to 192.168.1.0/0.0.0.0 has been added        (conflicts with 
our route to 0.0.0.0), disconnecting (routemon.cpp:598)

Both seem to indicate that the routing table is changed on DHCP 
renewal. Is there a way to prevent networkmanager from doing this? Or 
is this problem caused by something else possibly?

as you suspect, this is caused by NetworkManager. At various times
(e.g. when activating a connection, or on new DHCP lease), NM will
reinstall routes.


recently there was a related email thread:
https://mail.gnome.org/archives/networkmanager-list/2015
-May/msg00016.html

but no solution either.


We could change NM not only do any system-modification when it will
actually have any effect.
Like, re-installing a route, only if it is not yet currently there.


There was an idea to add a feature to "propert routes".
https://bugzilla.gnome.org/show_bug.cgi?id=749376
It's not clear how this feature could look like, but probably it should
be designed in a way, that you can tell NM ~not to configure~ certain
routes.


IMO ncsvc should allow you to white-list certain routes, so you could
say: don't tear down VPN when somebody messes with 192.168.1.0/24.


Thomas

Attachment: signature.asc
Description: This is a digitally signed message part



[Date Prev][Date Next]   [Thread Prev][Thread Next]   [Thread Index] [Date Index] [Author Index]