NetworkManager is a program for providing detection and configuration for systems to automatically connect to network. Your network can easily be shared to others using it. But If you want to implement DNS caching on your machine, you will find it annoying. I used to face conflict between NetworkManager/ConnectionSharing and DNS Caching, but now I find a workaround.
My DNS Caching Configure
/etc/NetworkManager/NetworkManager.conf
[main]
dhcp=dhclient
dns=dnsmasq
It works, but you need root privilege to start networksharing, like this: sudo nmcli con up xxxx. I have also tried using systemd/dnsmasq, but it doesn’t work at all.
When you start a shared network, NetworkManager will start dnsmasq listening on port 53.
Type pgrep -a dnsmasq, you will get:
/usr/bin/dnsmasq --conf-file --no-hosts --keep-in-foreground --bind-interfaces --except-interface=lo --clear-on-reload --strict-order --listen-address=10.42.0.1 --dhcp-range=10.42.0.10,10.42.0.254,60m --dhcp-option=option:router,10.42.0.1 --dhcp-lease-max=50 --pid-file=/var/run/nm-dnsmasq-xxxx.pid`
At first I tried disable the dnsmasq’s dns function, but finally I found these arguements in the source code of NetworkManager.
/* dnsmasq may read from it's default config file location, which if that
* location is a valid config file, it will combine with the options here
* and cause undesirable side-effects. Like sending bogus IP addresses
* as the gateway or whatever. So tell dnsmasq not to use any config file
* at all.
*/
nm_cmd_line_add_string (cmd, "--conf-file");
nm_cmd_line_add_string (cmd, "--no-hosts");
nm_cmd_line_add_string (cmd, "--keep-in-foreground");
nm_cmd_line_add_string (cmd, "--bind-interfaces");
nm_cmd_line_add_string (cmd, "--except-interface=lo");
nm_cmd_line_add_string (cmd, "--clear-on-reload");
You can recompile NetworkManager to solve the problem. But as the comment implies, you can add some arguements in dnsmasq’s default config file and hope it works.
Update: It doesn't work!!
I chose an another solution. If the arguements above couldn’t be changed, I could change the config files of DNS caching.
In /etc/NetworkManager/dnsmasq.d/, you should have:
listen-address=127.0.0.1 # no other listen addresses
no-dhcp-interface=lo
no-dhcp-interface=......
no-dhcp-interface=......
For IPv6:
listen-address=::1
Result:
pgrep -a dnsmasq
2393 /usr/bin/dnsmasq --no-resolv --keep-in-foreground --no-hosts --bind-interfaces --pid-file=/var/run/NetworkManager/dnsmasq.pid --listen-address=127.0.0.1 --conf-file=/var/run/NetworkManager/dnsmasq.conf --cache-size=400 --proxy-dnssec --conf-dir=/etc/NetworkManager/dnsmasq.d
2512 /usr/bin/dnsmasq --conf-file --no-hosts --keep-in-foreground --bind-interfaces --except-interface=lo --clear-on-reload --strict-order --listen-address=10.42.0.1 --dhcp-range=10.42.0.10,10.42.0.254,60m --dhcp-option=option:router,10.42.0.1 --dhcp-lease-max=50 --pid-file=/var/run/nm-dnsmasq-xxxx.pid
It seems there is no conflict in NetworkManager ... The wrong configure causes this case.