I run webmin/virtualmin on a new ubuntu server 22.04
Before I installed Virtualmin I changed hostname on it but now I see in the mail log this
Feb 4 06:00:32 server postfix/qmgr[631702]: 41B5D124505B: from=root@vmi2433889.contaboserver.net, size=703, nrcpt=1 (queue active)
Where does this come from
Likely the PTR, which is the reverse DNS for your IP address. Your host controls this, since they control the network block.
Some will allow you to edit the PTR name directly and some will delegate the IP to DNS servers of your choosing.
You should follow the docs for the PTR, too. Donât set it to a name youâll be virtually hosting in Virtualmin. (But the current one is probably fine as long as it resolves correctly both ways. It doesnât matter what PTR is, just that one exists and the name resolves back to the IP.)
I can set te PTR myself in the controlpanel by the host and that is correct on all servers so its something else
Then it must be the hostname of the system itself.
hostname -f
Last login: Mon Feb 3 14:24:55 2025 from 185.98.107.185
root@server:~# hostname -f
server.jv80.se
root@server:~#
A guess would be if Contabo set up/provided the initial image then you are probably using their DNS servers?
root@main:~# cat /etc/resolv.conf
domain onlinehome-server.com
search onlinehome-server.com
nameserver 10.255.255.4
nameserver 10.255.255.3I use cloudflare dns, has never used contabo dns
I donât think this is the same thing. Do
cat /etc/resolv.conf
or look here
Some DNS is answering to that and Iâd guess it would be Contaboâs.
root@main:~# ping vmi2433889.contaboserver.net
PING vmi2433889.contaboserver.net (167.86.100.222) 56(84) bytes of data.
64 bytes from jv80.se (167.86.100.222): icmp_seq=1 ttl=56 time=116 ms
64 bytes from jv80.se (167.86.100.222): icmp_seq=2 ttl=56 time=114 ms
64 bytes from jv80.se (167.86.100.222): icmp_seq=3 ttl=56 time=114 ms
64 bytes from jv80.se (167.86.100.222): icmp_seq=4 ttl=56 time=114 ms
64 bytes from jv80.se (167.86.100.222): icmp_seq=5 ttl=56 time=114 ms
^C
--- vmi2433889.contaboserver.net ping statistics ---
5 packets transmitted, 5 received, 0% packet loss, time 4002ms
rtt min/avg/max/mdev = 113.502/114.167/115.831/0.870 ms
Your Postfix is probably looking to their DNS servers. Iâd guess you have DNS turned off if you are using Cloudflare. That doesnât mean your local server is looking up requests at Cloudflare.
Interesting. When I installed webmin I added cloudflare dns but I can see that contabos is listed.
but still from where come the address. I changed hostname before I installed webmin
And again where does webmin find contabo address. Its nowhere
Most of these machines are set up with DHCP. Reboot the machine or possibly restart networking and the DHCP kicks in. I know on my home router I can make the DNS servers âstickyâ. Iâm pretty sure you can do that on Ubuntu also.
Note the resolution order. You can add your machine to the hosts file and it should start returning the name you expect. Iâm guessing that Postfix relies on resolvable host names so is checking DNS instead of blindly using the hostname.
When I look at the PTR, I see this:
$ host 167.86.100.222
222.100.86.167.in-addr.arpa domain name pointer jv80.se.
Not related to your specific question, but if youâre hosting email for jv80.se virtually in Virtualmin you shouldnât name the server that (and the PTR shouldnât be that). It should be anything else (server.jv80.se from above is fine as long as you add an A record for that name so it resolves both ways).
No that server host no email. 2 webshops on that server send mail via our email server using phpmail
See if the following command returns any results.
grep -rl "contaboserver.net" /etc/The above searches the â/etcâ folder recursively for files including âcontaboserver.netâ then returns just the filename in its results.
*** most system configs live inside the âetcâ folder tree. if something is found, it may lead to a solution. (this is just one possible path to search) ***
Which machine use dhcp you mean? If you mean my home computer you are wrong. I have a static IP
No. The Contabo server.
I really doubt that a company with 400000 +vps servers use dhcp
Vultr uses DHCP (Iâm sure they would to that or more VPSâs), how else would they distribute IPâs to new machine?
DHCP can be used to push specified IPs to specified clients giving best of both worlds.
As @shoulders has explained, DHCP is NOT always about assigning a ârandomâ IP address, but can actually be setup to âmapâ an IP to for instance a âMAC addressâ of a computer therefore making it âstaticâ in nature.
*** I do this within my own home network for instance ***
The primary difference is, instead of âhard-codingâ the static IP address in the intended system configuration, the network operator can configure the IP address assigned to a VPS or Bare Metal system at the ânetwork levelâ, then have the VPS or Bare Metal system request their IP address via DHCP.
Itâs quite common for large data centers to make use of DHCP in order to streamline deployment of servers.
