Cisco 7604 Configuration Guide - Page 233

Chapter 13 Identifying Traffic with Access Lists Adding an Extended Access List You can apply only one access list of each type (extended and EtherType) to each direction of an interface. You can apply the same access lists on multiple interfaces. See Chapter 15, "Permitting or Denying Network Access," for more information about applying an access list to an interface. Note If you change the access list configuration, and you do not want to wait for existing connections to time out before the new access list information is used, you can clear the connections using the clear local-host command. Allowing Broadcast and Multicast Traffic through the Transparent Firewall In routed firewall mode, broadcast and multicast traffic is blocked even if you allow it in an access list, including unsupported dynamic routing protocols and DHCP (unless you configure DHCP relay). Transparent firewall mode can allow any IP traffic through. This feature is especially useful in multiple context mode, which does not allow dynamic routing, for example. Note Because these special types of traffic are connectionless, you need to apply an extended access list to both interfaces, so returning traffic is allowed through. Table 13-2 lists common traffic types that you can allow through the transparent firewall. Table 13-2 Transparent Firewall Special Traffic Traffic Type DHCP Protocol or Port UDP ports 67 and 68 EIGRP Protocol 88 OSPF Protocol 89 Multicast streams The UDP ports vary depending on the application. RIP (v1 or v2) UDP port 520 Notes If you enable the DHCP server, then the FWSM does not pass DHCP packets. - - Multicast streams are always destined to a Class D address (224.0.0.0 to 239.x.x.x). - Adding an Extended ACE When you enter the access-list command for a given access list name, the ACE is added to the end of the access list unless you specify the line number. To add an ACE, enter the following command: hostname(config)# access-list access_list_name [line line_number] [extended] {deny | permit} protocol source_address mask [operator port] dest_address mask [operator port | icmp_type] [inactive] Tip Enter the access list name in upper case letters so the name is easy to see in the configuration. You might want to name the access list for the interface (for example, INSIDE), or for the purpose for which it is created (for example, NO_NAT or VPN). OL-20748-01 Catalyst 6500 Series Switch and Cisco 7600 Series Router Firewall Services Module Configuration Guide using ASDM 13-7