connectivity check

[Thomas Haller]

On Fri, 2024-06-07 at 16:36 +0200, Bojan Pogacar wrote:
> Hi!
> 
> This is my 20-connectivity.conf file:
> 
> [connectivity]
> uri=http://network-test.debian.org/nm
> interval=60
> 
> When testing with iptables to disable WAN connectivity like this: 
> iptables -I OUTPUT -o eth1 -j DROP
> 
> connection on first attempt switches over to LTE. Then I reenable WAN
> and disable again. Then I get LIMITED connectivity because of this:
> 
> Jun 07 14:31:09 10-0-0-5 NetworkManager[12389]: <debug> 
> [1717770669.1602] connectivity: (wwan0,IPv4,95) start request to 
> 'http://network-test.debian.org/nm' (try resolving 
> 'network-test.debian.org' using systemd-resolved)
> Jun 07 14:31:09 10-0-0-5 NetworkManager[12389]: <debug> 
> [1717770669.1677] connectivity: (wwan0,IPv6,96) skip connectivity
> check 
> due to no IP address configured
> Jun 07 14:31:09 10-0-0-5 NetworkManager[12389]: <debug> 
> [1717770669.1684] connectivity: (wwan0,IPv6,96) check completed:
> NONE; 
> no IP address configured
> Jun 07 14:31:09 10-0-0-5 NetworkManager[12389]: <debug> 
> [1717770669.2590] connectivity: (wwan0,IPv4,95) can't resolve a name
> via 
> systemd-resolved: GDBus.Error:org.freedesktop.DBus.Error.Timeout: All
> attempts to contact name servers or networks failed
> Jun 07 14:31:09 10-0-0-5 NetworkManager[12389]: <debug> 
> [1717770669.2619] connectivity: (wwan0,IPv4,95) start request to 
> 'http://network-test.debian.org/nm' (try resolving 
> 'network-test.debian.org' using system resolver)
> Jun 07 14:31:09 10-0-0-5 NetworkManager[12389]: <debug> 
> [1717770669.2765] connectivity: (wwan0,IPv4,95) failure to resolve
> name: 
> Error resolving “network-test.debian.org”: Temporary failure in name 
> resolution
> Jun 07 14:31:09 10-0-0-5 NetworkManager[12389]: <debug> 
> [1717770669.2770] connectivity: (wwan0,IPv4,95) check completed: 
> LIMITED; resolve-error
> 
> wwan0 has internet connection, but DNS resolver is not working,
> because 
> default route is on WAN, which I blocked.
> 
> I tried this setting: uri=http://1.1.1.1 <- IP instead of domain, but
> it 
> still tries to resolve http://1.1.1.1 and it doesn't succeed. It does
> not recognise, that resolver is not needed.
> 
> How can I resolve the issue? I have compiled into NetworkManager
> these 
> plugins: modemmanager ppp concheck
> 
> Full config:
> 
> # NetworkManager configuration:
> /etc/NetworkManager/NetworkManager.conf 
> (etc: 20-connectivity.conf)
> 
> [main]
> # plugins=
> # rc-manager=auto
> # migrate-ifcfg-rh=false
> # auth-polkit=true
> # dhcp=internal
> # iwd-config-path=
> dns=systemd-resolved
> configure-and-quit=no
> 
> [connectivity]
> uri=http://network-test.debian.org/nm
> interval=60
> 
> [logging]
> # backend=journal
> # audit=false
> level=DEBUG
> 
> [device]
> # wifi.backend=wpa_supplicant


First, to address this problem, you must use systemd-resolved. Either
via

  [main]
  dns=systemd-resovled

or via

  [main]
  systemd-resolved=true

you do that, so that's good.


Could it be, that you have strict RP filter? Check:

  grep ^ /proc/sys/net/ipv4/conf/*/rp_filter

If you see "1", that's strict. "0" or "2" is OK.


Thomas