Dnsmasq: Difference between revisions

From miki
Jump to navigation Jump to search
(Created page with " == Links == * DNS. * Linux networking. * Network troubleshooting. * D-Bus. == Troubleshooting == DNS is down: <source lang="bash"> nslookup google.be # Serve...")
 
Line 50: Line 50:
<source lang=bash>
<source lang=bash>
sudo pkill dnsmasq
sudo pkill dnsmasq
</source>

dnsmasq is usually started by NetworkManager:
<source lang="bash">
ps aux|grep dnsmasq
# nobody 128496 0.0 0.0 12976 4504 ? S 10:06 0:00 /usr/sbin/dnsmasq --no-resolv --keep-in-foreground
# --no-hosts --bind-interfaces --pid-file=/run/NetworkManager/dnsmasq.pid --listen-address=127.0.0.1 --cache-size=400
# --clear-on-reload --conf-file=/dev/null --proxy-dnssec --enable-dbus=org.freedesktop.NetworkManager.dnsmasq
# --conf-dir=/etc/NetworkManager/dnsmasq.d
</source>

This is configured in {{file|/etc/NetworkManager/NetworkManager.conf}}:
<source lang="bash">
cat /etc/NetworkManager/NetworkManager.conf
# [main]
# plugins=ifupdown,keyfile
# dns=dnsmasq
#
# ...
</source>

We also need to tell the dhclient to use dnsmasq, in file {{file|/etc/dhcp/dhclient.conf}}:
<source lang="diff">
#send dhcp-lease-time 3600;
#supersede domain-name "fugue.com home.vix.com";
-#prepend domain-name-servers 127.0.0.1;
+prepend domain-name-servers 127.0.0.1;
#require subnet-mask, domain-name-servers;
#timeout 60;
#retry 60;
</source>
</source>

Revision as of 09:18, 20 April 2022

Links

Troubleshooting

DNS is down:

nslookup google.be
# Server:       127.0.0.1
# Address:  127.0.0.1#53
# 
# ** server can't find google.be: NXDOMAIN

127.0.0.1:53 is served by dnsmasq:

sudo netstat -lpn | grep 127.0.0.1:53
# tcp        0      0 127.0.0.1:53            0.0.0.0:*               LISTEN      30718/dnsmasq       
# udp        0      0 127.0.0.1:53            0.0.0.0:*                           30718/dnsmasq

On Debian, this is configured in /etc/resolv.conf:

# Generated by NetworkManager
nameserver 127.0.0.1

Let's bypass dnsmasq to see if issue is there. For this, we use Google DNS 8.8.8.8:

cat /etc/resolv.conf
# # Generated by NetworkManager
# nameserver 8.8.8.8

nslookup google.be
# Server:       8.8.8.8
# Address:  8.8.8.8#53
# 
# Non-authoritative answer:
# Name: google.be
# Address: 216.58.213.163
# Name: google.be
# Address: 2a00:1450:4007:811::2003

DNS is back when bypassing dnsmasq.

Apparently killing dnsmasq is enough to restore the service (this will restore /etc/resolv.conf)

sudo pkill dnsmasq

dnsmasq is usually started by NetworkManager:

ps aux|grep dnsmasq
# nobody    128496  0.0  0.0  12976  4504 ?        S    10:06   0:00 /usr/sbin/dnsmasq --no-resolv --keep-in-foreground 
# --no-hosts --bind-interfaces --pid-file=/run/NetworkManager/dnsmasq.pid --listen-address=127.0.0.1 --cache-size=400
# --clear-on-reload --conf-file=/dev/null --proxy-dnssec --enable-dbus=org.freedesktop.NetworkManager.dnsmasq 
# --conf-dir=/etc/NetworkManager/dnsmasq.d

This is configured in /etc/NetworkManager/NetworkManager.conf:

cat /etc/NetworkManager/NetworkManager.conf
# [main]
# plugins=ifupdown,keyfile
# dns=dnsmasq
#
# ...

We also need to tell the dhclient to use dnsmasq, in file /etc/dhcp/dhclient.conf:

 #send dhcp-lease-time 3600;
 #supersede domain-name "fugue.com home.vix.com";
-#prepend domain-name-servers 127.0.0.1;
+prepend domain-name-servers 127.0.0.1;
 #require subnet-mask, domain-name-servers;
 #timeout 60;
 #retry 60;