/usr/sbin/puppetmasterd is in puppetmaster 2.7.23-1~deb7u3.
This file is owned by root:root, with mode 0o755.
The actual contents of the file can be viewed below.
1 2 3 4 | #!/usr/bin/ruby1.8
require 'puppet/application/master'
Puppet::Application[:master].run
|