Sockstat

sockstat is a FreeBSD tool that lists open ports.
A clone has been written for linux.

Documentation

FreeBSD manpage	https://www.freebsd.org/cgi/man.cgi?query=sockstat
Debian manpage	http://manpages.ubuntu.com/manpages/trusty/man1/sockstat.1.html

Install

# FreeBSD
# (pre-installed with base)

# Archlinux
# see https://packages.debian.org/unstable/main/sockstat
curl -#0 http://deb.debian.org/debian/pool/main/s/sockstat/sockstat_0.4.1.orig.tar.gz --output sockstat.tar.gz
tar -xvf sockstat.tar.gz 
cd sockstat
make
sudo make install

Usage

sockstat -4

# USER     COMMAND    PID   FD PROTO  LOCAL ADDRESS         FOREIGN ADDRESS
# root     wireguard- 97588 13 udp4   *:51891               *:*
# root     sshd       75092 4  tcp4   *:22                  *:*
# websrv   python2.7  63252 5  tcp4   127.0.0.1:8080        *:*
# root     syslogd    21271 6  udp4   *:514                 *:*