peeraddr

Returns the remote address as an array which contains address_family, port, hostname and numeric_address. It is defined for connection oriented socket such as TCPSocket.

If reverse_lookup is true or :hostname, hostname is obtained from numeric_address using reverse lookup. Or if it is false, or :numeric, hostname is same as numeric_address. Or if it is nil or ommitted, obeys to ipsocket.do_not_reverse_lookup. See Socket.getaddrinfo also.

TCPSocket.open("www.ruby-lang.org", 80) {|sock|
  p sock.peeraddr #=> ["AF_INET", 80, "carbon.ruby-lang.org", "221.186.184.68"]
  p sock.peeraddr(true)  #=> ["AF_INET", 80, "221.186.184.68", "221.186.184.68"]
  p sock.peeraddr(false) #=> ["AF_INET", 80, "221.186.184.68", "221.186.184.68"]
  p sock.peeraddr(:hostname) #=> ["AF_INET", 80, "carbon.ruby-lang.org", "221.186.184.68"]
  p sock.peeraddr(:numeric)  #=> ["AF_INET", 80, "221.186.184.68", "221.186.184.68"]
}