peeraddr

        # IPSocket.peeraddr

(from ruby core)
---
    ipsocket.peeraddr([reverse_lookup]) => [address_family, port, hostname, numeric_address]

---

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 the same as numeric_address. Or if it is `nil`
or omitted, 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, "carbon.ruby-lang.org", "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"]
    }