# ss
# Another utility to investigate sockets

# Options:
#   -4/-6   list ipv4/ipv6 sockets
#   -n      numeric addresses instead of hostnames
#   -l      list listening sockets
#   -u/-t/-x list udp/tcp/unix sockets
#   -p      Show process(es) that using socket

# Show all listening TCP ports, including the corresponding process.
ss -tlp

# Show a summary of all ports connecting to 192.168.2.1 via port 80.
ss -t dst 192.168.2.1:80

# Show all SSH-related connection.
#
# Documentation on the filter syntax can be installed via the following command
# if on a Debian- or Ubuntu-based distribution of Linux:
#
#     sudo apt-get install iproute2-doc
#
ss -t state established '( dport = :ssh or sport = :ssh )'

# Display timer information.
ss -tno

# Filter connections by TCP state.
ss -t4 state established