Dynamic routing protocols will not be allowed, however, we can add static routes for traffic originating on the ASA.

DHCP relay – The transparent firewall can act as a DHCP server, but it does not support the DHCP relay commands.

Related – Configure Multiple Context Mode in Cisco ASA Features Not Supported by Transparent Mode –

The firewall can allow any traffic through by using normal extended Access Control Lists (ACL).

Even though the appliance acts as a Layer 2 bridge, Layer 3 traffic cannot pass through the security appliance from a lower security level to a higher security level interface.

Each interface of the ASA must be a different VLAN interface.

The management IP address must be in the same subnet as the connected network.

A management IP address is required on the ASA.

Can run in single firewall context or in multiple firewall contexts.

MAC lookups are performed instead of routing table lookups.

The firewall bridges packets from one VLAN to the other instead of routing them.

Transparent firewall mode supports only two interfaces (inside and outside).

Related – ASA Firewall Security Levels Key Characteristics of ASA Firewall When Configured In Transparent Mode –

Non-IP traffic can be allowed (IPX, MPLS, BPDUs.

Multicast streams can traverse the firewall.

Protocols such as HSRP, VRRP, GLBP can pass.

Routing protocols can establish adjacencies through the firewall.

No change to existing IP addressing or Servers.

1 st let’s understand what we are getting out by using Firewall in Transparent mode : Benefits of Using a Firewall in Transparent Mode –

Cisco asa 5505 configuration example