Description of problem:

nmap seems to be build without SSH2 support. However, the NSE & LUA scripts are included in the RPM. This may lead to confusion.



How reproducible: 100%


Steps to Reproduce:
1. check nmap status
[root@rhel8-1 nmap]# nmap -V | grep without                                                                                                                                                  
Compiled without: libssh2 libz

2. check ssh2 related files included in the RPM
[root@rhel8-1 nmap]# rpm -ql nmap | grep ssh                                                                                                                                                 
/usr/share/nmap/nselib/libssh2-utility.lua                                                                                                                                                   
/usr/share/nmap/nselib/libssh2.luadoc                                                                                                                                                        
/usr/share/nmap/nselib/ssh1.lua                                                                                                                                                              
/usr/share/nmap/nselib/ssh2.lua                                                                                                                                                              
/usr/share/nmap/scripts/ssh-auth-methods.nse                                                                                                                                                 
/usr/share/nmap/scripts/ssh-brute.nse                                                                                                                                                        
/usr/share/nmap/scripts/ssh-hostkey.nse                                                                                                                                                      
/usr/share/nmap/scripts/ssh-publickey-acceptance.nse                                                                                                                                         
/usr/share/nmap/scripts/ssh-run.nse                                                                                                                                                          
/usr/share/nmap/scripts/ssh2-enum-algos.nse                                                                                                                                                  
/usr/share/nmap/scripts/sshv1.nse

3. Try to call the ssh-* scripts

$ nmap -vvv -d -sS -p2200 -sV --version-light -sC --script=ssh-publickey-acceptance,ssh-auth-methods -oA ssh-test localhost

Actual results:

```
Starting Nmap 7.70 ( https://nmap.org ) at 2019-10-14 05:23 EDT
[...]
NSE: Using Lua 5.3.
NSE: Arguments from CLI:
NSE: module 'libssh2' not found:
        NSE failed to find nselib/libssh2.lua in search paths.
        no field package.preload['libssh2']
        no file '/usr/local/share/lua/5.3/libssh2.lua'
        no file '/usr/local/share/lua/5.3/libssh2/init.lua'
        no file '/usr/local/lib/lua/5.3/libssh2.lua'
        no file '/usr/local/lib/lua/5.3/libssh2/init.lua'
        no file './libssh2.lua'
        no file './libssh2/init.lua'
        no file '/usr/local/lib/lua/5.3/libssh2.so'
        no file '/usr/local/lib/lua/5.3/loadall.so'
        no file './libssh2.so'
stack traceback:
        /usr/bin/../share/nmap/nse_main.lua:293: in function 'stdnse.silent_require'
        /usr/bin/../share/nmap/nselib/libssh2-utility.lua:14: in main chunk
        [C]: in function 'require'
        /usr/bin/../share/nmap/scripts/ssh-auth-methods.nse:3: in function </usr/bin/../share/nmap/scripts/ssh-auth-methods.nse:1>                                                           
NSE: Failed to load '/usr/bin/../share/nmap/scripts/ssh-auth-methods.nse'.
NSE: module 'libssh2' not found:
        NSE failed to find nselib/libssh2.lua in search paths.
        no field package.preload['libssh2']
        no file '/usr/local/share/lua/5.3/libssh2.lua'
        no file '/usr/local/share/lua/5.3/libssh2/init.lua'
        no file '/usr/local/lib/lua/5.3/libssh2.lua'
        no file '/usr/local/lib/lua/5.3/libssh2/init.lua'
        no file './libssh2.lua'
        no file './libssh2/init.lua'
        no file '/usr/local/lib/lua/5.3/libssh2.so'
        no file '/usr/local/lib/lua/5.3/loadall.so'
        no file './libssh2.so'
stack traceback:
        /usr/bin/../share/nmap/nse_main.lua:293: in function 'stdnse.silent_require'
        /usr/bin/../share/nmap/nselib/libssh2-utility.lua:14: in main chunk
        [C]: in function 'require'
        /usr/bin/../share/nmap/scripts/ssh-publickey-acceptance.nse:9: in function </usr/bin/../share/nmap/scripts/ssh-publickey-acceptance.nse:1>
```


Expected results:

=> The scripts requiring the missing libssh2 module should not be included in the RPM, since they can not be used.


Additional info:

libssh2-utility requires libssh2, which is omitted in the build. Thus all scripts requiring libssh2-utility will fail.

I think the following files can be removed :

ssh-auth-methods.nse
ssh-brute.nse
ssh-publickey-acceptance.nse
ssh-run.nse
libssh2-utility.lua