This helped me with installing Nexpose, I hope it helps you.

Step One

Before you install Nexpose just like everything else make sure you meet the system requirements .. like the recommendation to have 8gb of memory. Nexpose will only run on a 64bit OS, etc.

http://www.rapid7.com/products/nexpose/system-requirements.jsp

 

Step Two

Download Nexpose. Community edition is free but does require a valid email (one that isnt from a free provider like gmail or yahoo, my .edu email worked).

http://www.rapid7.com/products/nexpose/compare-downloads.jsp

 

Step Three

You need to change the default port for postgresql because both metasploit and nexpose use port 5432 by default.
https://community.rapid7.com/community/nexpose/blog/2014/06/11/kali-for-ya

To change the port in kali first stop the service from running

Next navigate to /etc/postgresql and hunt for postgresql.conf

Then edit the port number in postgresql.conf .. with nano of course

I changed mine to 5431.

Now restart postgresql

 restarting-postgresql

 

Step Four

Now navigate to the directory of the installer. The file should be called something like “NeXposeSetup-Linux64.bin” and is most likely in your downloads folder. Try /root/Downlaods.

Change the permissions of the installer by running

Then run the installer

installer-running

If you messed up and found this after you already installed Nexpose without changing the default ports, you need to uninstall Nexpose and reinstall.

Then reinstall from the steps above.

Remember that the default port to access the web gui from your browser after installation is 3780

If you have any trouble with Metasploit not connecting to your database, check the port settings in the database.yml in