Paranoid Penguin - Rehabilitating Clear-Text Network Applications with Stunnel
And that, I hope, is enough to start you down the path of Stunnel mayhem. As usual, I've scratched only the surface. I leave it up to you to explore Stunnel's ability to authenticate tunnels with client-certificate checking, its support for TCPwrappers-style access controls and the myriad global and service-specific options supported in stunnel.conf. Let the stunnel(8) man page be your guide, and may your single-TCP-port-using unencrypted-TCP applications be eavesdroppable no more.
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Mick Bauer, CISSP, is Linux Journal's security editor and an IS security consultant in Minneapolis, Minnesota. He's the author of Building Secure Servers With Linux (O'Reilly & Associates, 2002).