Question Change DNS server that plesk internally uses?

[jmar83]

Server operating system version

Debian 10.13

Plesk version and microupdate number

18.0.64 Update 1

Hi there

As the title says! ;-)

I had some problems with automatic downloading webapp firewall many times, so maybe its a DNS problem. Because of that, i would like to change to Google DNS 8.8.8.8 & 8.8.4.4.

Thank you very much for your feedback(s)

 

[Raul A.]

Hi,

What issue are you encountering?

In terms of changing the used resolves, you need root access to edit /etc/resolv.conf. Add before other nameserver lines:

nameserver 8.8.8.8
nameserver 1.1.1.1

However, you might experience issues using these name servers when checking IP addresses against RBL when receiving emails.

 

[jmar83]

Thank you very much!

 

[jmar83]

Hmmm, interesting... So it seems, it was necessary to use "-f" option to make it read-only, not just "+i" (so the file will not be re-created with old DNS servers on system reboot):

chattr -f +i /etc/resolv.conf

Otherwise, i got the messsage "chattr: Operation not supported while reading flags on /etc/resolv.conf"

I don't know what this is, i never had that issue on a Debian 10 i installed by myself (?). But maybe plesk servers are secured ("hardened") in a special way, who knows?

 

[jmar83]

After a restart, the file has its old values...

 

[jmar83]

Oh, "-f" flag only supresses the error message, so i don't need to wonder, lol

chattr(1) - Linux manual page

 

[jmar83]

Hmmm... its a "tmpfs" file system (my Plesk is hosted on a VServer on an external service provider, maybe it because of his configuration)

df -Th /etc/resolv.conf
Filesystem Type Size Used Avail Use% Mounted on
tmpfs tmpfs 1.0G 9.3M 1015M 1% /run

 

[jmar83]

But /etc mount point is not tmpfs... the backup file i've created, /etc/resolv.conf.0, is on ext4:
df -Th /etc/resolv.conf.0
Filesystem Type Size Used Avail Use% Mounted on
/dev/ploop38847p1 ext4 50G 31G 17G 65% /


While /etc/resolv.conf links to that path:

ls -l /etc/resolv.conf
lrwxrwxrwx 1 root root 29 Jul 22 2020 /etc/resolv.conf -> ../run/resolvconf/resolv.conf



...i don't know it's a good idea so remove that symlink via:

rm /etc/resolv.conf
touch /etc/resolv.conf


Hmm... "Never touch a running system?" Maybe it's a risk to destroy the whole system with things like that?

 

[AYamshanov]

ls -l /etc/resolv.conf
lrwxrwxrwx 1 root root 29 Jul 22 2020 /etc/resolv.conf -> ../run/resolvconf/resolv.conf



...i don't know it's a good idea so remove that symlink via:

Just an idea. "When resolvconf is properly installed, the resolv.conf file is replaced by a symbolic link to /etc/resolvconf/run/resolv.conf and the resolver instead uses the dynamically generated linked file." (c) resolvconf - Wikipedia

Probably, you can configure resolvers with Ubuntu Manpage: resolvconf.conf — resolvconf configuration file

 

[jmar83]

Thank you very much for your feedback!

 

[jmar83]

Hmmm... the symlink target is also on a tempfs file system, so i can't protect it by setting read only flag via "chattr +i ..." after i changed the DNS list in /etc/resolvconf/run/resolv.conf:

chattr +i /etc/resolvconf/run/resolv.conf
chattr: Inappropriate ioctl for device while reading flags on /etc/resolvconf/run/resolv.conf

 

[jmar83]

Only one workaround?

- Remove symlink
- Create new file /etc/resolv.conf
- Make it read-only with "chattr" on its ext4 location?

I can't believe that such a trivial thing is so tricky...

 

[mow]

Hmmm... the symlink target is also on a tempfs file system, so i can't protect it by setting read only flag via "chattr +i ..." after i changed the DNS list in /etc/resolvconf/run/resolv.conf:

chattr +i /etc/resolvconf/run/resolv.conf
chattr: Inappropriate ioctl for device while reading flags on /etc/resolvconf/run/resolv.conf

That's the same file you tried this on before (chattr follows the symlink). You are supposed to edit the resolvconf.conf file, like explained in @AYamshanov's link.

 

[jmar83]

OK, thx, will look on it ASAP

df -Th /etc/init/resolvconf.conf
Filesystem Type Size Used Avail Use% Mounted on
/dev/ploop38847p1 ext4 50G 31G 17G 66% /

 

[jmar83]

Hmmm. in all these file ("tail", "head") they belong to /etc/init/resolvconf.conf is written: "Do not edit ... will not be saved"

to complicated...

so:

1.) unlink /etc/resolv.conf
2.) touch /etc/resolv.conf
3.) nano /etc/resolv.conf
4.) Write DNS entries into /etc/resolv.conf
5.) chattr +i unlink /etc/resolv.conf
6.) init 6
7.) cat /etc/resolv.conf
7a.) = works!


So thank you anyway!

 

[jmar83]

*chattr +i /etc/resolv.conf