Recently, I have encountered the need to acquaint myself with the Security world of Cisco and due to an insufficient amount of funds to buy myself a couple of ASAs, I am using simulated ASAs using GNS3. If you have never used GNS3 before, it is an absolutely must-need for any networking student or professional. You can download it here www.gns3.com/.
So, to begin with, you will need to obtain the initrd and kernel files for the ASA ISO (which can be found using your Google skills). When booted, you are more likely than not, going to encounter a nice little issue whereby if you assign an IP address to an interface and issue a “no shut” command, the IP address fails to register when you enter the “show int ip brief” command.
Now, this might be where I show my inexperience with ASAs, and it actually took me a very long time looking on forums for the answer, but the answer was indeed very simple. If you enter the interface configuration mode and enter “nameif xxxx” the interface will auto-magically come online!
I will add screenshots later to clarify this but I hope this helps you out!