Cryptography Reference
In-Depth Information
APPENDIX
B
Installing TCPDump
and OpenSSL
The code developed in this topic has been tested to work on both Windows and
Linux systems. If you want to follow the examples, you also need both OpenSSL
and TCPdump installed locally. If you're on a Linux system, OpenSSL may already
be available. TCPDump you usually need to install yourself. This appendix goes
through the installation process for both systems for both software packages.
Installing TCPDump
TCPDump
is a handy, versatile utility that can capture and display every byte
that's exchanged on any given socket in a system. Obviously, if you're working
with network protocols, this can be incredibly useful, although it's less useful
when you're working with SSL/TLS-secured traffi c. After all, the whole point
of SSL/TLS is to protect users from these sorts of packet sniffers; TCPDump
can come in handy, however, when debugging certifi cate verifi cation problems
or handshake problems.
TCPDump has its roots in Unix/Linux systems and as such is a command-line
tool. You might fi nd a more modern incarnation called
Ethereal
(also sometimes
called
Wireshark
) preferable, especially if you're running a Windows system.
However, the examples in this topic use TCPDump strictly because its textual
output lends itself much better to print.
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