[Pkg-utopia-maintainers] Bug#1006724: network-manager: DNS information not cleaned correctly when switching of networks

[Vincent Danjean]

Package: network-manager
Version: 1.36.0-2
Severity: normal

  Hi,

  When I change of location with my laptop (putting it in suspend-to-ram
during the transfert), I found several times that the network become slow.
  Looking more in details, I discovered that network-manager does not cleanup
correctly the DNS information of the previous (wired) connection. As I have
specific settings, the network-manager connection is not the same at work and
at home (specific Mac fixed at home, forced fixed IPv6 at work, ...)
  The DNS information still present in /etc/resolv.conf comes from DHCP
information (at work or at home) that are kept when the connexion is switched
by network-manager.
  Even when I disable the connexion, the DNS information are kept.

  Here is the current situation (with anonymisation of IP and dnsdomain) where
I manually disable the wired connexion (so I do not have network access for
now):
vdanjean at eyak:/run/resolvconf/interface$ nmcli 
docker0: connecté à docker0
        "docker0"
        bridge, XX:XX:XX:XX:XX:5D, sw, mtu 1500
        inet4 172.17.0.1/16
        route4 169.254.0.0/16 metric 1000
        route4 172.17.0.0/16 metric 0
        inet6 fe80::42:45ff:fe7a:55d/64

3C:DC:BC:D0:26:00: déconnecté
        "Silk"
        1 connexion disponible
        bt (bluez), 3C:DC:BC:D0:26:00, hw

enx98fc84e13b03: déconnecté
        "Realtek RTL8153"
        2 connexions disponibles
        ethernet (r8152), XX:XX:XX:XX:XX:03, connexion automatique, hw, mtu 1500

en-wifi: déconnecté
        "Intel 8265 / 8275"
        3 connexions disponibles
        wifi (iwlwifi), XX:XX:XX:XX:XX:29, connexion automatique, hw, mtu 1500

p2p-dev-en-wifi: déconnecté
        "p2p-dev-en-wifi"
        wifi-p2p, hw

veth315cdd3: non-géré
        "veth315cdd3"
        ethernet (veth), XX:XX:XX:XX:XX:A7, sw, mtu 1500

lo: non-géré
        "lo"
        loopback (unknown), 00:00:00:00:00:00, sw, mtu 65536

DNS configuration:
        servers: AAA.AAA.24.30 BBB.BBB.1.22
        domains: mywork1.fr mywork2.fr

        servers: AAAA:AAAA:AAAA:AAAA:4 BBBB:BBBB:BBBB:BBBB::7

        servers: AAA.AAA.24.30 BBB.BBB.1.22
        domains: mywork1.fr mywork2.fr

        servers: AAAA:AAAA:AAAA:AAAA:4 BBBB:BBBB:BBBB:BBBB::7

        servers: AAA.AAA.24.30 BBB.BBB.1.22
        domains: mywork1.fr mywork2.fr

        servers: AAAA:AAAA:AAAA:AAAA:4 BBBB:BBBB:BBBB:BBBB::7

Utilisez « nmcli device show » pour obtenir des informations complètes sur les >

Consultez les pages de manuel nmcli(1) et nmcli-examples(7) pour les détails co>
vdanjean at eyak:/run/resolvconf/interface$ cat NetworkManager 
search mywork1.fr mywork2.fr
nameserver AAA.AAA.24.30
nameserver BBB.BBB.1.22
nameserver AAAA:AAAA:AAAA:AAAA:4
nameserver BBBB:BBBB:BBBB:BBBB::7
vdanjean at eyak:/run/resolvconf/interface$ cat /etc/resolv.conf 
# Dynamic resolv.conf(5) file for glibc resolver(3) generated by resolvconf(8)
#     DO NOT EDIT THIS FILE BY HAND -- YOUR CHANGES WILL BE OVERWRITTEN
# 127.0.0.53 is the systemd-resolved stub resolver.
# run "resolvectl status" to see details about the actual nameservers.

nameserver AAA.AAA.24.30
nameserver BBB.BBB.1.22
nameserver AAAA:AAAA:AAAA:AAAA:4
search mywork1.fr mywork2.fr


Only if I restart NetworkManager, then these outdated informations go out:
vdanjean at eyak:/run/resolvconf/interface$ sudo systemctl restart NetworkManager
vdanjean at eyak:/run/resolvconf/interface$ cat NetworkManager 
search home.fr sub1.home.fr sub2.home.fr
nameserver 10.77.0.2
nameserver fd77:53::1
nameserver 192.168.77.1
vdanjean at eyak:/run/resolvconf/interface$

If I disable my home connextion (that NetworkManager connects automatically on restart),
I come back to the previous nmcli state (ie no active connexion) as before, but, this time,
/run/resolvconf/interface/NetworkManager do not exists and the "DNS
configuration:" section in nmcli is not printed.



  So, it seems that sometimes NetworkManager forgets to clean DNS information
(as shown by nmcli) when switching between networks connexion. As manual
restart of the NetworkManager deamon allows one to fix that.


  Regards,
    Vincent




-- System Information:
Debian Release: bookworm/sid
  APT prefers stable-updates
  APT policy: (500, 'stable-updates'), (500, 'stable-security'), (500, 'oldstable-updates'), (500, 'unstable'), (500, 'testing'), (500, 'stable'), (500, 'oldstable'), (1, 'experimental')
Architecture: amd64 (x86_64)
Foreign Architectures: i386, armel, mipsel

Kernel: Linux 5.16.0-3-amd64 (SMP w/4 CPU threads; PREEMPT)
Kernel taint flags: TAINT_OOT_MODULE
Locale: LANG=fr_FR.utf8, LC_CTYPE=fr_FR.utf8 (charmap=UTF-8), LANGUAGE not set
Shell: /bin/sh linked to /bin/dash
Init: systemd (via /run/systemd/system)

Versions of packages network-manager depends on:
ii  adduser          3.118
ii  dbus             1.14.0-1
ii  libaudit1        1:3.0.7-1
ii  libbluetooth3    5.62-2
ii  libc6            2.33-7
ii  libcurl3-gnutls  7.81.0-1
ii  libglib2.0-0     2.70.4-1
ii  libgnutls30      3.7.3-4+b1
ii  libjansson4      2.13.1-1.1
ii  libmm-glib0      1.18.6-2
ii  libndp0          1.6-1+b1
ii  libnewt0.52      0.52.21-5+b1
ii  libnm0           1.36.0-2
ii  libpsl5          0.21.0-1.2
ii  libreadline8     8.1.2-1
ii  libselinux1      3.3-1+b1
ii  libsystemd0      250.3-2
ii  libteamdctl0     1.31-1
ii  libudev1         250.3-2
ii  policykit-1      0.105-33
ii  udev             250.3-2

Versions of packages network-manager recommends:
ii  dnsmasq-base [dnsmasq-base]  2.86-1.1
ii  libpam-systemd               250.3-2
ii  modemmanager                 1.18.6-2
ii  ppp                          2.4.9-1+1
ii  wireless-regdb               2021.08.28-1
ii  wpasupplicant                2:2.9.0-23

Versions of packages network-manager suggests:
ii  iptables       1.8.7-1
pn  libteam-utils  <none>

Versions of packages network-manager is related to:
ii  isc-dhcp-client  4.4.2-P1-1

-- no debconf information