I upgraded a 16.04 Ubuntu server to 22.04. Migration to 18.04 & 20.04 worked well. The upgrade to 22.04 broke my DNS config. I found a lot of tutorials to configure the whole network using netplan ... but I don't feel very confortable with them (I'm afraid to break everything). I have a lot of network interfaces on the server but nothing in /etc/netplan. I wonder if I have to create a netplan file with all the network interfaces or just the broken one.
Here is the result of 'nmcli device show' command:
GENERAL.DEVICE: docker0 GENERAL.TYPE: bridge GENERAL.HWADDR: 02:42:99:76:F4:CE GENERAL.MTU: 1500 GENERAL.STATE: 10 (non-géré) GENERAL.CONNECTION: -- GENERAL.CON-PATH: -- IP4.ADDRESS[1]: 172.17.0.1/16 IP4.GATEWAY: -- IP4.ROUTE[1]: dst = 172.17.0.0/16, nh = 0.0.0.0, mt = 0 IP6.GATEWAY: -- GENERAL.DEVICE: docker_gwbridge GENERAL.TYPE: bridge GENERAL.HWADDR: 02:42:FA:EB:F8:75 GENERAL.MTU: 1500 GENERAL.STATE: 10 (non-géré) GENERAL.CONNECTION: -- GENERAL.CON-PATH: -- IP4.ADDRESS[1]: 172.18.0.1/16 IP4.GATEWAY: -- IP4.ROUTE[1]: dst = 172.18.0.0/16, nh = 0.0.0.0, mt = 0 IP6.ADDRESS[1]: fe80::42:faff:feeb:f875/64 IP6.GATEWAY: -- IP6.ROUTE[1]: dst = fe80::/64, nh = ::, mt = 256 GENERAL.DEVICE: enp2s0f0 GENERAL.TYPE: ethernet GENERAL.HWADDR: D8:D3:85:B9:34:20 GENERAL.MTU: 1500 GENERAL.STATE: 10 (non-géré) GENERAL.CONNECTION: -- GENERAL.CON-PATH: -- WIRED-PROPERTIES.CARRIER: marche IP4.ADDRESS[1]: 10.231.226.41/23 IP4.GATEWAY: 10.231.227.254 IP4.ROUTE[1]: dst = 0.0.0.0/0, nh = 10.231.227.254, mt = 0 IP4.ROUTE[2]: dst = 10.231.226.0/23, nh = 0.0.0.0, mt = 0 IP6.ADDRESS[1]: fe80::dad3:85ff:feb9:3420/64 IP6.GATEWAY: -- IP6.ROUTE[1]: dst = fe80::/64, nh = ::, mt = 256 GENERAL.DEVICE: enp2s0f1 GENERAL.TYPE: ethernet GENERAL.HWADDR: D8:D3:85:B9:34:22 GENERAL.MTU: 1500 GENERAL.STATE: 10 (non-géré) GENERAL.CONNECTION: -- GENERAL.CON-PATH: -- WIRED-PROPERTIES.CARRIER: arrêt IP4.GATEWAY: -- IP6.GATEWAY: -- GENERAL.DEVICE: vethdcb1995 GENERAL.TYPE: ethernet GENERAL.HWADDR: C2:05:F6:52:3F:61 GENERAL.MTU: 1500 GENERAL.STATE: 10 (non-géré) GENERAL.CONNECTION: -- GENERAL.CON-PATH: -- WIRED-PROPERTIES.CARRIER: marche IP4.GATEWAY: -- IP6.ADDRESS[1]: fe80::c005:f6ff:fe52:3f61/64 IP6.GATEWAY: -- IP6.ROUTE[1]: dst = fe80::/64, nh = ::, mt = 256 GENERAL.DEVICE: lo GENERAL.TYPE: loopback GENERAL.HWADDR: 00:00:00:00:00:00 GENERAL.MTU: 65536 GENERAL.STATE: 10 (non-géré) GENERAL.CONNECTION: -- GENERAL.CON-PATH: -- IP4.ADDRESS[1]: 127.0.0.1/8 IP4.GATEWAY: -- IP6.ADDRESS[1]: ::1/128 IP6.GATEWAY: -- IP6.ROUTE[1]: dst = ::1/128, nh = ::, mt = 256 The problem is the enp2s0f0 device has no DNS defined. My questions are:
- how to add my DNS records safely? Maybe there's a clean solution easier than netplan. Clean excludes hacking files generated by generated by resolvconf like /etc/resolvconf/resolv.conf.d/head
- If I have to create all interfaces in the file, is there a way to create a netplan file from current settings to reduce the risk of errors?
PS: I do not know if it is important but systemd-resolve is not installed on the machine and /etc/resolv.conf.d contains reference to it:
# 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 "systemd-resolve --status" to see details about the actual nameservers. nameserver 127.0.0.53 search DOMAINS 1 Answer
I finally found the solution here:
In case the link die in the future: Create a file:
sudo mkdir /etc/systemd/resolved.conf.d/ sudo nano /etc/systemd/resolved.conf.d/dns_servers.conf Add my dns in this file:
[Resolve] DNS=8.8.8.8 1.1.1.1 Then restart systemd-resolved
sudo systemctl restart systemd-resolved It works even after reboot :-)
PS : No idea why my DNS configuration was lost during the upgrade from 20.04 to 22.04.
