/usr/bin/diameterc is in erlang-diameter 1:16.b.3-dfsg-1ubuntu2.2.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/bin/../lib/erlang/lib/diameter-1.5/bin/diameterc
/usr/bin/../lib/erlang/lib/diameter-1.5/bin/diameterc