Frequently Asked Questions
$Id: faq.html,v 1.7 1999/11/29 14:15:43 renaud Exp $
Questions regarding the project :
Questions about the compilation options :
Questions regarding the cipher layer :
Questions regarding runtime errors :
Questions regarding the plugins :
What is the Nessus Project ?
The 'Nessus' Project was started in early 1998, and first released in
April 1998. At this time, the most complete free security scanner was
SATAN, which is clearly outdated, and you could see the emergence
of several commercial ones, that were clearly too expensive.
The Nessus Security Scanner is not only another security auditing tool. It
is a security auditing as I think it should be - never trust the version
number, never trust that a given service is listenning on the good
port (do all the web servers on earth listen on port 80 ?).
The Nessus Security Scanner is free, open-sourced and wants to be easy to use.
Who funds it ?
Nobody funds the Nessus project. The authors give their free time to write
their part. Jordan Hrycaj gives
his free time to write the cipher layer. I give my free time to update
the security tests (among other things). Users give their free time to
report bugs or suggest enhancements.
Why is it called the Nessus project ?
No special reason. I needed a name when I started it. Mainly because
the names my project and security scanner were too vague
and too common.
How do I enable a compilation option ?
Which compilation options are available ?
The only working compilation option at this time is
the cipher layer.
- configure --enable-cipher[=NN] : will enable the cipher layer. If you
add the =NN argument, then you can specify the length of the keys. For instance,
--enable-cipher=40 will set the length of the keys to 40 bits.
- configure --enable-pthreads : will enable the pthreads instead
of the fork(). This is not recommanded as it shows to be very instable.
I get an 'undefined reference to yylex' at link-time
!
You need bison and flex to compile nessus-libraries, not yacc and lex.
So, install bison and flex, then recompile nessus-libraries from scratch, and
try again.
I have just installed nessus-libraries, but libnasl will not find it !
I can not log in !
If you are using the Unix client :
If you compiled nessus with the cipher layer support, then you can not
add users by editing the nessusd.users file. Instead, you should :
- add a user using 'nessusd -P <user>,<password>
- log in using the Unix client
If you are using NessusW or NessusJ (Win32 and Java clients) :
Add in nessusd.conf the line : force_pubkey_auth = no
I got a CRC error during the connection !
Something was changed in the way the cipher layer works. Delete
your /usr/local/share/nessus/nessus*keys* and ~/.nessus.keys
and try again
I got a spoof alert upon the connection !
This is because the key of the server has changed. Delete your
~/.nessus.keys and try again
I got an error during a scan : "20104: Reached maximum limits of threads, allready"
Quoting Jordan Hrycaj on the mailing list :
you should enable/uncomment the
directive "track_iothreads = yes" in ()/etc/nessusd.conf.
Then try to provoke that table overflow error, again. It should not
occur, anymore but you should find some complaints in the nessusd server
logs concerning ungegisterd channels and the like.
A scan produced no result !
The plugins window is empty !
You must first connect to the nessusd server.
If you are connected to a nessusd server already, make sure
you are using Nessus 0.98.4 or better, which fixes a nasty
bug in the way the tabs were drawn.
(Questions regarding plugins)
This web page is Copyright (C) 1999 Renaud Deraison