http://www.stunnel.org/
http://www-6.ibm.com/jp/developerworks/security/011005/j_s-stun.html
http://stunnel.threechan.jp/
http://www.atmarkit.co.jp/fsecurity/rensai/securitytips/018stunnnel.html
http://www.aconus.com/~oyaji/mail2/stunnel.htm
http://www1.orangesoft.co.jp/wstunnel/
http://old.netsecurity.ne.jp/article/3/2702.html