dnsmasq receive reverse lookup request unexpectedly

Kernels & Hardware, configuring network, installing services

dnsmasq receive reverse lookup request unexpectedly

Postby blinkfish » 2020-09-07 09:45

I have set two SUSE server with dnsmasq setup. server A IP address 10.11.11.11, server B IP dress 10.11.11.12

In server A /etc/resolv.conf
----------------------------------
nameserver 127.0.0.1
nameserver 10.11.11.11

In server B /etc/resolv.conf
----------------------------------
nameserver 127.0.0.1
nameserver 10.11.11.12

In the log of dnsmasq what can be found in /var/log/messages, there are a log of reverse dns lookup from the other server. i.e. log in server A receive request from server B and vice versa.

sample log in server A
---------------------------
2020-09-07T14:20:35.654681+08:00 gcnsmtp12 dnsmasq[13615]: query[PTR] 133.72.250.10.in-addr.arpa from 10.11.11.12
2020-09-07T14:20:35.654906+08:00 gcnsmtp12 dnsmasq[13615]: forwarded 133.72.250.10.in-addr.arpa to 10.11.11.12

sample log in server B
---------------------------
2020-09-07T15:11:26.988071+08:00 gcnsmtp14 dnsmasq[16242]: query[PTR] 10.12.250.10.in-addr.arpa from 10.11.11.11
2020-09-07T15:11:26.988325+08:00 gcnsmtp14 dnsmasq[16242]: forwarded 10.12.250.10.in-addr.arpa to 10.911.11.11


It seems that server A will send reverse dns lookup request to server B for any servers connecting to server A and vice versa.

I have no idea why reverse dns lookup happend. I have tried to find out which PID send the reverse dns lookup request with tcpdump, auditctl and lsof, but no luck. Only tcpdump can capture the traffic, but there is no PID related to.

Most grateful if anybody can help.
blinkfish
 
Posts: 4
Joined: 2020-09-02 09:09

Re: dnsmasq receive reverse lookup request unexpectedly

Postby cuckooflew » 2020-09-07 10:08

Welcome to Debian User Forums,
Please learn to use code boxes, and also What does this have to do with Debian ?
Please Read What we expect you have already Done
Search Engines know a lot, and
"If God had wanted computers to work all the time, He wouldn't have invented RESET buttons"
and
Just say NO to help vampires!
cuckooflew
 
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Location: Some where out west

Re: dnsmasq receive reverse lookup request unexpectedly

Postby blinkfish » 2020-09-08 05:43

Sorry, wrong post.
blinkfish
 
Posts: 4
Joined: 2020-09-02 09:09


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