Support multiple daemon instances with systemd in Debian.

debian/default

@@ -1,13 +1,15 @@
-# This file has five functions: 
-# 1) to completely disable starting dnsmasq, 
-# 2) to set DOMAIN_SUFFIX by running `dnsdomainname` 
+# This file has six functions:
+# 1) to completely disable starting this dnsmasq instance
+# 2) to set DOMAIN_SUFFIX by running `dnsdomainname`
 # 3) to select an alternative config file
 #    by setting DNSMASQ_OPTS to --conf-file=<file>
 # 4) to tell dnsmasq to read the files in /etc/dnsmasq.d for
 #    more configuration variables.
 # 5) to stop the resolvconf package from controlling dnsmasq's
 #    idea of which upstream nameservers to use.
-# For upgraders from very old versions, all the shell variables set 
+# 6) to avoid using this dnsmasq instance as the system's default resolver
+#    by setting DNSMASQ_EXCEPT="lo"
+# For upgraders from very old versions, all the shell variables set
 # here in previous versions are still honored by the init script
 # so if you just keep your old version of this file nothing will break.
 
@@ -24,10 +26,15 @@ ENABLED=1
 # in backups made by dpkg.
 CONFIG_DIR=/etc/dnsmasq.d,.dpkg-dist,.dpkg-old,.dpkg-new
 
-# If the resolvconf package is installed, dnsmasq will use its output 
-# rather than the contents of /etc/resolv.conf to find upstream 
+# If the resolvconf package is installed, dnsmasq will use its output
+# rather than the contents of /etc/resolv.conf to find upstream
 # nameservers. Uncommenting this line inhibits this behaviour.
-# Note that including a "resolv-file=<filename>" line in 
+# Note that including a "resolv-file=<filename>" line in
 # /etc/dnsmasq.conf is not enough to override resolvconf if it is
 # installed: the line below must be uncommented.
 #IGNORE_RESOLVCONF=yes
+
+# If the resolvconf package is installed, dnsmasq will tell resolvconf
+# to use dnsmasq under 127.0.0.1 as the system's default resolver.
+# Uncommenting this line inhibits this behaviour.
+#DNSMASQ_EXCEPT="lo"