Hello,
I'm not sure if this is a systemd-resolved or NetworkManager question
but it involves both (I know Thomas HALLER is a member of this list too)
on
Fedora release 36 (Thirty Six) using the following kernel and packages
5.19.16-200.fc36.x86_64 #1 SMP PREEMPT_DYNAMIC
systemd-250.8-1.fc36.x86_64
systemd-resolved-250.8-1.fc36.x86_64
NetworkManager-1.38.4-1.fc36.x86_64
I'm using a proprietary vpn client which does not seem to work very well
with systemd-resolved. As a matter of fact it seems to create a manual
NM profile which does not include dns properties and it seems to (try
to) set /etc/resolv.conf aside (F5 vpn linux client f5fpc for the record)
Making it work is not the question here. I'm trying to understand how
the 2 nameservers it configures may end up in
/run/systemd/resolve/resolv.conf (and global systemd-resolved config as
shown by resolvectl status) ONLY when I switch from a non
systemd-resolved config then back to a systemd-resolved config
Here's exactly what I'm doing/experiencing:
Starting from
a) default NetworkManager config:
# grep -iE 'dns|rc\.manager' NetworkManager.conf
# ls -l conf.d/
total 0
b) systemd-resolved stub-resolv.conf mode:
# ls -l /etc/resolv.conf
lrwxrwxrwx 1 root root 37 Oct 26 19:15 /etc/resolv.conf ->
/run/systemd/resolve/stub-resolv.conf
and with (not linked from /etc/resolv.conf) :
/run/systemd/resolve/resolve.conf following content:
nameserver 192.168.1.1
nameserver 2a01:cb00:7e1:3300:aa6a:bbff:fe6e:190
search home
matching my auto wireless NM profile
1) I start the vpn client
obviously it does not work very well with systemd-resolved as I don't
get corresponding nameserver (10.33.1.2,10.33.1.3) anywhere and name
resolution does not work for corresponding zones
/run/systemd/resolve/resolve.conf content has not changed
2) I stop the vpn client, and switch to the following setup
# rm /etc/resolv.conf
rm: remove symbolic link '/etc/resolv.conf'? y
# cat <<EOF > /etc/NetworkManager/conf.d/foo.conf
> [main]
> dns=default
> rc.manager=file
> EOF
# reboot
-> after the reboot the /etc/resolv.conf link as been recreated : why ?
(/run/systemd/resolve/resolv.conf hasn't changed, which seems normal to me)
3) I remove it again and reboot
# rm /etc/resolv.conf
rm: remove symbolic link '/etc/resolv.conf'? y
# reboot
-> this time /etc/resolv.conf is as expected a regular file which
content is handled by NM:
$ ls -l /etc/resolv.conf
-rw-r--r-- 1 root root 114 Oct 26 20:22 /etc/resolv.conf
$ cat /etc/resolv.conf
# Generated by NetworkManager
search home
nameserver 192.168.1.1
nameserver 2a01:cb00:7e1:3300:aa6a:bbff:fe6e:190
4) I start the vpn client
it wrote to /etc/resolv.conf (which seems wrong to me but is out of
scope here)
$ cat /etc/resolv.conf
#F5 Networks Inc. :File modified by VPN process
search pasteur.fr home
nameserver 10.33.1.2
nameserver 10.33.1.3
the 2 nameservers it provided do not appear in
/run/systemd/resolve/resolv.conf
6) I stop the vpn client switch back to my orgininal config, and reboot
# rm /etc/NetworkManager/conf.d/foo.conf
rm: remove regular file '/etc/NetworkManager/conf.d/foo.conf'? y
# rm /etc/resolv.conf
rm: remove regular file '/etc/resolv.conf'? y
# ln -s /run/systemd/resolve/stub-resolv.conf /etc/resolv.conf
# reboot
-> everything looks as expected
7) I start the vpn client
-> its provided nameserver appear in /run/systemd/resolv/resolv.conf
(and resolution of related zones work)
-> why ? Where does the info come from ?
nameserver 10.33.1.2
nameserver 10.33.1.3
nameserver 192.168.1.1
# Too many DNS servers configured, the following entries may be ignored.
nameserver 2a01:cb00:7e1:3300:aa6a:bbff:fe6e:190
search pasteur.fr home
Can you help me figure out what's happening or at least how can the
behavior seem to change with what seem a rollback to the initial state ?
Thanks for your help
--
Thomas HUMMEL
