sudo lsof -i -P -n | grep LISTEN
netstat -tulnp | grep LISTEN

Show iptables nat with packet counters:

iptables -L -t nat -nvx

tcpdump -n -nn -v -i eth0 host 192.168.0.1

conntrack-tools (apt-get install conntrack):

conntrack -L [-j 192.168.0.1]

apache2ctl fullstatus

apache2 -V

python -m SimpleHTTPServer
python -m http.server 8000