ftp implements the File Transfer Protocol client for the exchange of files to and from remote hosts.
The ssh client program implements a secure shell session to a remote host.
A web browser, such as Firefox, implements an http connection to a remote http server.
ping sends ICMP echo requests to a remote host to verify functionality.
dig obtains information from DNS servers.
traceroute attempts to display the route over which packets must travel to a remote host.
fwhois queries a whois database to determine the owner of a domain or IP address.