readme

ssl sniffer源代码

SSLsniffer.
----------------------------------------------
Written by: Eu-Jin Goh ([e-mail])
            Stanford University April 2001
 
----------------- GNU Public License -----------
Copyright (C) 2001  Eu-Jin Goh

This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or (at
your option) any later version.

This program is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
General Public License for more details.
 
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307,
USA.

INSTALLATION:
-------------

First type 'tar zxvf sslsniffer-1_2.tar.gz' to extract the files.
Just use the Makefile. You might have to change the paths of the
headers and libraries for openSSL.

USAGE:
-----

sslsniffer [-p <local port>] [-np <remote port> <remote hostname/ip>]

-p <local port>

specifies which port the sslsniffer will listen to on the local
machine.

-np <remote port> <remote hostname/ip>

no means no proxy which means that the CONNECT message is not
sent. Instead the remote host name (it also accepts numerical ip
addresses) and the remote port number is specified.

If not options are given, the sslsniffer listens on the default port
8888 and assumes that a CONNECT message will be sent as the first
packet.

----------------------------------------------------------------

PROGRAM NOTES:

Version 1.21
------------

Bug fixes. 

The version number of a connection would not be updated if the first
packet is not a V2 packet. This doesn't break anything except that
certificates will not be parsed in that connection.

Forgot to place a break statement in a switch while parsing certain
handshake packet types. Symptoms were that the sniffer would try to
parse more than it should and print out garbage values. Fortunately,
the packet that triggers this was not a common one.

Version 1.2
-----------

Main changes in this version is that support for parsing SSLV2 packets
has been implemented. It took a lot less time than I thought it would
because the rewritten code base makes it easy to add this in and also
because sslv2 is a much simpler protocol to parse than TLS.

It seems that SSLV2 doesn't offer support for certificate chains.

I removed a couple of structs from the sslsniffer.h because I forgot
that C doesn't guarantee how structs are laid out in memory and hence
I shouldn't be relying on structs to typecast network data for pointer
access.


Version 1.1
-----------

I totally rewrote the entire sslsniffer so that it handles fragmented
packets in a cleaner fashion. The entire structure is changed and I'm
much happier with the current incarnation now. It's also a lot more
flexible and I plan to add support for SSLV2 very soon. I've already
written that part but it's under the old style and I want to rewrite
it as well.

It now handles those multiple handshake packets in one record case
perfectly (I think!) and also those fragmented packets. The style of
the code has been changed to make it a lot more readable.

Also, the no connect case where you want to connect directly to the
server without sending a CONNECT request has been made as a flag
rather than spinning it off to another program.


Version 1.02.
------------

I was printing out the reverse of session ID for a V3 hello and also
for the RSA encrypted premaster secret. the function extractParams
suffered from this problem too. there was a one by off error in these
same functions


Version 1.01 / 1.00 
------------------- 

This program uses the OpenSSL libraries and Dan Boneh's code for the
processing of the certificates. Other than that, everything else was
coded from scratch.

The proxy handles SSLV3/TLS servers only. It deals with the first
clientHello packet being in SSLV2 format but other than that, no other
SSLV2 packets are handled. You can typically recognise when the site
is using SSLV2 when the first byte of the error messages that the
proxy prints out are -128 or -126. try it on wellsfargo to see.  This
was developed in RedHat linux 6.1 using glibc 2.1.3-8 and openssl
0.94. Works best in linux using x86 architecture. On some machines,
the print outs in hex will appear to have either leading or trailing
zeros.

Please send all bug reports to me. It would be great if you could
attach the output when the bug ocurred too. I typically use 'sslproxy
>! out' and read the out file later because there is usually too much
output to read at one go.

NOTE: 

I have not ported this to big endian architectures yet, i think it's
not too hard since all that is needed is to change the function
threeBytesToInt so that it converts the handshake length field to from
a three byte number in network byte order to the host byte order.

If the server returns a cipher suite that is unknown, currently my
proxy doesn't handle it too well. it still works but doesn't parse the
messages properly.

Occasionally (very rarely), the multiple application data fragments
aren't handled properly and invalid type errors keeping appearing but
the proxy should still work properly after that connection.

Netscape enterprise servers were rather flakey on the proxy and i
added some code so that it works properly. I tested on stronghold
servers and this proxy works best with those. This is due to the fact
that enterprise servers place multiple handshake messages within a
single TLS record while stronghold sends out handshake messages with
their own TLS record.

The application data and certificate messages might be split up over
several packets and the code that i have currently handles this fine
but is rather ugly. Given more time, i would rewrite it so that it's
cleaner.