usocket
USOCKET is a networking portability layer for BSD-style sockets.

Homepage: http://common-lisp.net/project/usocket

License: MIT

USOCKET currently supports 10 CL implementations: ABCL, ACL, ECL, CLISP, CMUCL, LispWorks, MCL, CCL, SBCL, and SCL.

See also: IOlib, another view point for portable networking library in Common Lisp.