On Unix machines, placing commands into the .forward file was also a common method of regaining access. For the account ``username¡®¡® a .forward file might be constructed as follows:
permutations of this method include alteration of the systems mail aliases file (most commonly located at /etc/aliases). Note that this is a simple permutation, the more advanced can run a simple script from the forward file that can take arbitrary commands via stdin (after minor preprocessing).
PS: The above method is also useful gaining access a companies mailhub (assuming there is a shared a home directory FS on &nbs>
the client and server).
> Using smrsh can effectively negate this backdoor (although it¡®s quite > possibly still a problem if you allow things like elm¡®s filter or > procmail which can run programs themselves...).