[Dnsmasq-discuss] PID file option problem

[Mohsen Zohrevandi]

Hi,

I am using dnsmasq 2.68 on Ubuntu 14.04 and when I run the following
command I get an error:

$ sudo dnsmasq --no-dhcp-interface --bind-interfaces
--listen-address=169.254.1.1

dnsmasq: failed to create listening socket for port 53: Address already in
use

Running "sudo netstat -anlp | grep -w LISTEN" shows:

tcp        0      0 127.0.1.1:53            0.0.0.0:*               LISTEN
     1272/dnsmasq
tcp        0      0 10.0.3.1:53             0.0.0.0:*               LISTEN
     1140/dnsmasq
tcp        0      0 0.0.0.0:22              0.0.0.0:*               LISTEN
     1033/sshd
tcp        0      0 127.0.0.1:631           0.0.0.0:*               LISTEN
     2190/cupsd
tcp        0      0 0.0.0.0:17500           0.0.0.0:*               LISTEN
     2484/dropbox
tcp6       0      0 fe80::1c44:45ff:fec7:53 :::*                    LISTEN
     1140/dnsmasq
tcp6       0      0 :::22                   :::*                    LISTEN
     1033/sshd
tcp6       0      0 ::1:631                 :::*                    LISTEN
     2190/cupsd

​However, if I run the following command there is no error and dnsmasq
successfully binds to the specified address:

$ sudo dnsmasq --no-dhcp-interface *--pid-file* --bind-interfaces
--listen-address=169.254.1.1
$ sudo netstat -anlp | grep -w LISTEN
* ​​tcp        0      0 169.254.1.1:53 <http://169.254.1.1:53>
 0.0.0.0:*               LISTEN      3345/dnsmasq    *
tcp        0      0 127.0.1.1:53            0.0.0.0:*               LISTEN
     1272/dnsmasq
tcp        0      0 10.0.3.1:53             0.0.0.0:*               LISTEN
     1140/dnsmasq
tcp        0      0 0.0.0.0:22              0.0.0.0:*               LISTEN
     1033/sshd
tcp        0      0 127.0.0.1:631           0.0.0.0:*               LISTEN
     2190/cupsd
tcp        0      0 0.0.0.0:17500           0.0.0.0:*               LISTEN
     2484/dropbox
tcp6       0      0 fe80::1c44:45ff:fec7:53 :::*                    LISTEN
     1140/dnsmasq
tcp6       0      0 :::22                   :::*                    LISTEN
     1033/sshd
tcp6       0      0 ::1:631                 :::*                    LISTEN
     2190/cupsd

​So somehow when I specify --pid-file​ option, it works, but not otherwise.
Also I noticed that no matter what is specified for the pid-file option, it
writes the pid to /var/run/dnsmasq.pid even in the above case when it is
supposed to disable pid-file:

$ cat /var/run/dnsmasq.pid
*3345*

If I specify another file to be used for pid-file, it still writes the pid
​to /var/run/dnsmasq.pid:

$ sudo kill 3345
$ sudo netstat -anlp | grep -w LISTEN
tcp        0      0 127.0.1.1:53            0.0.0.0:*               LISTEN
     1272/dnsmasq
tcp        0      0 10.0.3.1:53             0.0.0.0:*               LISTEN
     1140/dnsmasq
tcp        0      0 0.0.0.0:22              0.0.0.0:*               LISTEN
     1033/sshd
tcp        0      0 127.0.0.1:631           0.0.0.0:*               LISTEN
     2190/cupsd
tcp        0      0 0.0.0.0:17500           0.0.0.0:*               LISTEN
     2484/dropbox
tcp6       0      0 fe80::1c44:45ff:fec7:53 :::*                    LISTEN
     1140/dnsmasq
tcp6       0      0 :::22                   :::*                    LISTEN
     1033/sshd
tcp6       0      0 ::1:631                 :::*                    LISTEN
     2190/cupsd
​$ ​
sudo rm /var/run/dnsmasq.pid
$ sudo dnsmasq --no-dhcp-interface
* ​​--pid-file=/tmp/test.pid* --bind-interfaces --listen-address=169.254.1.1
$ sudo netstat -anlp | grep -w LISTEN
* ​​tcp        0      0 169.254.1.1:53 <http://169.254.1.1:53>
 0.0.0.0:*               LISTEN      3362/dnsmasq    *
tcp        0      0 127.0.1.1:53            0.0.0.0:*               LISTEN
     1272/dnsmasq
tcp        0      0 10.0.3.1:53             0.0.0.0:*               LISTEN
     1140/dnsmasq
tcp        0      0 0.0.0.0:22              0.0.0.0:*               LISTEN
     1033/sshd
tcp        0      0 127.0.0.1:631           0.0.0.0:*               LISTEN
     2190/cupsd
tcp        0      0 0.0.0.0:17500           0.0.0.0:*               LISTEN
     2484/dropbox
tcp6       0      0 fe80::1c44:45ff:fec7:53 :::*                    LISTEN
     1140/dnsmasq
tcp6       0      0 :::22                   :::*                    LISTEN
     1033/sshd
tcp6       0      0 ::1:631                 :::*                    LISTEN
     2190/cupsd
*​​$ cat /var/run/dnsmasq.pid *
*​​3362*
*​​$ cat /tmp/test.pid*
*​​cat: ​​/tmp/test.pid: No such file or directory*

​I searched the CHANGELOG ​in the git repository to see if there was a bug
related to this in later versions (I know I don't have the latest version)
but I did not find anything.
The strange thing about this is that I have two other instances of dnsmasq
running on my machine and they both have their separate pid files:

$ ps ax | grep dnsmasq
*1140* ... dnsmasq -u lxc-dnsmasq --strict-order --bind-interfaces
*--pid-file=/run/lxc/dnsmasq.pid* --conf-file= --listen-address 10.0.3.1
--dhcp-range 10.0.3.2,10.0.3.254 --dhcp-lease-max=253 --dhcp-no-override
--except-interface=lo --interface=lxcbr0
--dhcp-leasefile=/var/lib/misc/dnsmasq.lxcbr0.leases --dhcp-authoritative

*1272* ... /usr/sbin/dnsmasq --no-resolv --keep-in-foreground --no-hosts
--bind-interfaces
*--pid-file=/run/sendsigs.omit.d/network-manager.dnsmasq.pid*
--listen-address=127.0.1.1 --conf-file=/var/run/NetworkManager/dnsmasq.conf
--cache-size=0 --proxy-dnssec
--enable-dbus=org.freedesktop.NetworkManager.dnsmasq
--conf-dir=/etc/NetworkManager/dnsmasq.d

3362 ... dnsmasq --no-dhcp-interface --pid-file=/tmp/test.pid
--bind-interfaces --listen-address=169.254.1.1
...

$ cat /run/lxc/dnsmasq.pid
*1140*
$ cat /run/sendsigs.omit.d/network-manager.dnsmasq.pid
*1272*


​Thanks,

Mohsen Zohrevandi
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