The Cisco ASA 5505 is the smallest model in the newest 5500 series of Cisco firewalls. It is a great product for small businesses (5-10 employees) or even for home network use. However, if you need to create a DMZ zone (in addition to your Inside and Outside zones) in order to install a publicly accessible server (e.g WEB server, MAIL server etc), then the default basic license won’t work for you. The basic license does not allow more than 2 security zones. You will need to upgrade to “Security Plus” license which also enhances some other firewall parameters (more firewall connections, more remote access VPN sessions, trunking with 20 VLANs).
The Licensing for the ASA 5505 is as following:
Cisco ASA 5505 10 User Firewall Edition Bundle
Includes: 10 users, 8-port Fast Ethernet switch with 2 Power over Ethernet ports, 10 IPsec VPN peers, 2 SSL VPN peers, Triple Data Encryption Standard/Advanced Encryption Standard (3DES/AES) license.Cisco ASA 5505 50 User Firewall Edition Bundle
Includes: 50 users, 8-port Fast Ethernet switch with 2 Power over Ethernet ports, 10 IPsec VPN peers, 2 SSL VPN peers, 3DES/AES license.
Cisco ASA 5505 Unlimited User Firewall Edition Bundle
Includes: Unlimited users, 8-port Fast Ethernet switch with 2 Power over Ethernet ports, 10 IPsec VPN peers, 2 SSL VPN peers, 3DES/AES license.
Cisco ASA 5505 Security Plus Firewall Edition Bundle
Includes: Unlimited users, 8-port Fast Ethernet switch with 2 Power over Ethernet ports, 25 IPsec VPN peers, 2 SSL VPN peers, DMZ support, Stateless Active/Standby high availability, Dual ISP support, 3DES/AES license.
Source from: http://www.cisco-tips.com/cisco-asa-5505-firewall-license-restriction-for-dmz/
