Hey guys. Great tutorial. I followed something similar to this tutorial on this website: tom.postnix.org/?p=116
Like some of you though I was getting this error code:
Code:
/opt/nessus//sbin/nessusd: error while loading shared libraries: libssl.so.7: cannot open shared object file: No such file or directory
Executing nessusd failed. Make sure your library loader is configured properly
and that nessusd is in your $PATH
To fix this, as the other guy mentioned you just have to change the linking command from:
Code:
ln libssl.so libssl.so.6
ln libcrypto.so libcrypto.so.6
To This:
Code:
ln libssl.so libssl.so.7
ln libcrypto.so libcrypto.so.7
And everything should go ahead perfectly 
Another strange error that I ran into was when I attempted to use the registration code. I received an odd error:
That was all I received and after a wee bit of digging I managed to put two and two together to find out why this was happening. I was using different proxies to connect to the internet which was causing a problem with nessus's ability to connect to the internet. I was sure of how to configure nessus to use the proper proxy (if anyone knows the command line syntax that would be AMAZING!!). So all I had to do was go in and put that back to normal and all was well.
I know most of you aren't as dumb as me and probably won't make this mistake but I though I would share it without anyways just in case 
Hope this helps other new users to backtrack 3 and nessus as it did me 
thanks