[dnsdist] dnsdist 1.5.1 on Debian 10.8: snmpd socket and privileges

[Aleš Rygl]

Hello,

I am struggling a bit on dnsdist after upgrade to from 1.4.0 to 1.5.1. I 
am using Debian 10.8 and dnsdist with SNMP support enabled. It looks 
like dnsdist systemd unit file forces dnsdist to drop privileges to 
_dnsdist user and _dnsdist group in 1.5.1:

[Service]
ExecStartPre=/usr/bin/dnsdist --check-config
# Note: when editing the ExecStart command, keep --supervised and 
--disable-syslog
ExecStart=/usr/bin/dnsdist --supervised --disable-syslog
User=_dnsdist
Group=_dnsdist

The issue is that with such options it can not reach snmpd socket any more:

Feb 23 15:19:14 rzt-dns-lb2 dnsdist[20011]: Warning: Failed to connect 
to the agentx master agent (/var/agentx/master):

The permisions to the socket file (Debian default):

# ll /var
total 56
drwx------  2 root root   4096 Sep 23 16:59 agentx

ll  /var/agentx
total 0
srwxr-xr-x 1 root root 0 Feb 23 15:32 bmc
srwxr-xr-x 1 root root 0 Feb 23 16:01 master

# ll /var/agentx  /var/agentx/master
srwxr-xr-x 1 root root    0 Feb 23 16:01 /var/agentx/master

My idea was that changing mode of agentx directory above to 755 could 
help but it is not like that. I had to force dnsdist to run with root 
privileges to make it work again.

What should be the correct setup to run dnsdist under _dnsdist account 
again and SNMP enabled?

Many thanks

With regards

Ales