NetworkManager dnsmasq exited with error: Network access problem (address in use, permissions)の修正

Overview

以下のように、/var/log/syslogがエラーで溢れているのを治す。

Oct 12 09:52:32 myhost NetworkManager[817]: <warn>  [1507769552.4205] dnsmasq[0xcd4ab0]: dnsmasq exited with error: Network access problem (address in use, permissions) (2)
Oct 12 09:52:32 myhost NetworkManager[817]: <warn>  [1507769552.6835] dnsmasq[0xcd4ab0]: dnsmasq exited with error: Network access problem (address in use, permissions) (2)
Oct 12 09:52:32 myhost NetworkManager[817]: <warn>  [1507769552.9465] dnsmasq[0xcd4ab0]: dnsmasq exited with error: Network access problem (address in use, permissions) (2)
Oct 12 09:52:33 myhost NetworkManager[817]: <warn>  [1507769553.1983] dnsmasq[0xcd4ab0]: dnsmasq exited with error: Network access problem (address in use, permissions) (2)

対処方法

$ sudo dpkg-reconfigure resolvconf

/etc/NetworkManager/NetworkManager.conf

[main]
plugins=ifupdown,keyfile,ofono
-dns=dnsmasq
+#dns=dnsmasq

[ifupdown]
managed=false

以下はダメだった

sudo apt-get remove --purge network-manager network-manager-*
sudo apt-get install --reinstall network-manager

で、network managerの再installでは解決しなかった。
なお、上を試してしまうと、DNSを引けなくなるので、以下のような対処も必要になった。。。

/etc/resolvconf/resolv.conf.d/head

# Dynamic resolv.conf(5) file for glibc resolver(3) generated by resolvconf(8)
#     DO NOT EDIT THIS FILE BY HAND -- YOUR CHANGES WILL BE OVERWRITTEN

nameserver 8.8.8.8

以下も試していた。

sudo rm /etc/resolv.conf
sudo ln -s /run/resolvconf/resolv.conf /etc/resolv.conf
sudo resolvconf -u
sudo service network-manager restart