netstat

Running service in TCP port

netstat -nltp

Internet gateway

netstat -rn

netstat -rn | grep default

Connected IP address

netstat -ntu|awk '{print $5}'|cut -d: -f1 -s|sort|uniq -c|sort -nk1 -r

Alive connection for HTTP service

netstat -ant | grep -E ':80|:443' | grep -v grep | wc -l

Watch connections

watch 'for port in 80 443; do
  echo -n "port $port: "
  netstat -ant | grep -E ":$port" |
    grep -v grep | wc -l
done'