Why not just use IP?
I created a nice system, whereby if your IP is changed (or someone is
hacking your session), the session is destroyed, and the user must log in.
Does not add much overhead either.

Also, I built it using database (using my own session functions in
savehandler), that stores the ip as well.
This prevents people snooping.

Still not 100% secure I imagine, but much better.


"Mar Tin" <[EMAIL PROTECTED]> wrote in message
> Dear all:
> Until I read the article "PHP Session security"
> (http://www.webkreator.com/php/configuration/php-session-security.html)
> I haven't noticed how insecure PHP Sessions are.
> Basically there're 2 problems:
> *) It's possible to hijack a session if you know the
> SID (session id)
>  1) If you're on a shared server (cheap webhosting)
> other users can get the SIDs by doing "ls /tmp/sess_*"
> (/tmp/ is defined on session.save_path on the config
> file, so it may be different).
>  2) When a user clicks on an external link, the
> browser sends the REFERER url and sometimes it
> contains the SID (if session.use_trans_sid is enabled)
> PHP offers a security measure: with
> session.referer_check it will reject SIDs comming from
> other referers, but the referer url can be easily
> forged.
> *) Users can read session data from the session files,
> which are owned by the server process (every user
> which has an account on the webserver can read server
> owned files)
> (If you're intrested in the subject I would recommend
> to read full the article:
> http://www.webkreator.com/php/configuration/php-session-security.html)
> I have developed some functions to avoid this
> problems. They replace the standard session functions
> (using session_set_save_handler), so you only have to
> include the file at the beggining of your script and
> (afaik) you're safe :)
> This is the idea:
> Apart from the session cookie, I set another one (with
> the same name and the string '_sec' appended). On this
> cookie I set a random KEY.
> The name of the file which contains the session data
> is the md5 hash of the SID and the KEY together. This
> turns impossible to guess the session id by looking at
> the filenames.
> To hide the data inside the file, the serialized
> string is crypted using the KEY as password, so nobody
> can see the content of your user's sessions.
> You can find the code here:
> http://www.n3rds.com.ar/files/docs/php_sessions/sess_handler.txt
> Im looking for suggestions to make it 100% compatible
> with the standard session functions, and I would like
> to hear some thougts about the idea
> Martin Sarsale
> __________________________________________________
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