Software Licenses 10-User License The Cisco PIX 501 Firewall 10-user license supports up to 10 concurrent source IP addresses from your internal network to traverse through the PIX 501. The integrated DHCP server supports up to 32 DHCP leases. 50-User License The Cisco PIX 501 Firewall 50-user license supports up to 50 concurrent source IP addresses from your internal network to traverse through the PIX 501. The integrated DHCP server supports up to 128 DHCP leases. As your needs grow, a 10-to-50 user upgrade license is also available, which allows you to extend your investment in PIX 501 equipment. 3DES and DES Licenses The PIX 501 has two optional encryption licenses (168-bit 3DES and 56-bit DES) available either at the time of ordering the appliance, or as an upgrade that can be purchased later. Note that US export restrictions may apply to these licenses.