< Object

Class Socket provides access to the underlying operating system socket implementations. It can be used to provide more operating system specific functionality than the protocol-specific socket classes but at the expense of greater complexity. In particular, the class handles addresses using +struct sockaddr+ structures packed into Ruby strings, which can be a joy to manipulate.

Exception Handling

Ruby‘s implementation of Socket causes an exception to be raised based on the error generated by the system dependent implementation. This is why the methods are documented in a way that isolate Unix-based system exceptions from Windows based exceptions. If more information on particular exception is needed please refer to the Unix manual pages or the Windows WinSock reference.

Documentation by

  • Zach Dennis
  • Sam Roberts
  • Programming Ruby from The Pragmatic Bookshelf.

Much material in this documentation is taken with permission from Programming Ruby from The Pragmatic Bookshelf.


Method Alias Description
bind → original_resolv_bind
connect → original_resolv_connect
send → original_resolv_send



Visibility Signature
public bind (host, port)
public connect (host, port)
public recvfrom_nonblock (...)
public send (mesg, flags, *rest)

Instance Method Detail

bind(host, port)

connect(host, port)

udpsocket.recvfrom_nonblock(maxlen) => [mesg, sender_inet_addr]
udpsocket.recvfrom_nonblock(maxlen, flags) => [mesg, sender_inet_addr]

Receives up to maxlen bytes from udpsocket using recvfrom(2) after O_NONBLOCK is set for the underlying file descriptor. flags is zero or more of the MSG_ options. The first element of the results, mesg, is the data received. The second element, sender_inet_addr, is an array to represent the sender address.

When recvfrom(2) returns 0, Socket#recvfrom_nonblock returns an empty string as data. It means an empty packet.


  • maxlen - the number of bytes to receive from the socket
  • flags - zero or more of the MSG_ options


     require 'socket'
     s1 =
     s1.bind("", 0)
     s2 =
     s2.bind("", 0)
     s1.send "aaa", 0[s2])
     p s2.recvfrom_nonblock(10)  #=> ["aaa", ["AF_INET", 33302, "localhost.localdomain", ""]]

Refer to Socket#recvfrom for the exceptions that may be thrown if the call to recvfrom_nonblock fails.

UDPSocket#recvfrom_nonblock may raise any error corresponding to recvfrom(2) failure, including Errno::EAGAIN.


send(mesg, flags, *rest)