Dell S5148F-ON OS10 Enterprise Edition User Guide Release 10.3.2E-R2 - Page 373

• Source and destination TCP port number • Source and destination UDP port number For ACL, TCP, and UDP filters, match criteria on specific TCP or UDP ports. For ACL TCP filters, you can also match criteria on established TCP sessions. When creating an ACL, the sequence of the filters is important. You can assign sequence numbers to the filters as you enter them or OS10 can assign numbers in the order you create the filters. The sequence numbers display in the show running-configuration and show ip access-lists [in | out] command output. Ingress and egress hot-lock ACLs allow you to append or delete new rules into an existing ACL without disrupting traffic flow. Existing entries in the CAM shuffle to accommodate the new entries. Hot-lock ACLs are enabled by default and support ACLs on all platforms. NOTE: Hot-lock ACLs support ingress ACLs only. MAC ACLs MAC ACLs filter traffic on the Layer 2 (L2) header of a packet. This traffic filtering is based on: Source MAC packet MAC address range-address mask in 3x4 dotted hexadecimal notation, and any to denote that the rule matches address all source addresses. Destination MAC packet address MAC address range-address-mask in 3x4 dotted hexadecimal notation, and any to denote that the rule matches all destination addresses. Packet protocol Set by its EtherType field contents and Assigned protocol number for all protocols. VLAN ID Set in the packet header Class of service Present in the packet header IPv4/IPv6 and MAC ACLs apply separately for inbound and outbound packets. You can assign an interface to multiple ACLs, with a limit of one ACL per packet direction per ACL type. IP fragment handling OS10 supports a configurable option to explicitly deny IP fragmented packets, particularly for the second and subsequent packets. This option extends the existing ACL command syntax with the fragments keyword for all Layer 3 (L3) rules: • Second and subsequent fragments are allowed because you cannot apply a L3 rule to these fragments. If the packet is to be denied eventually, the first fragment must be denied and the packet as a whole cannot be reassembled. • The system applies implicit permit for the second and subsequent fragment prior to the implicit deny. • If you configure an explicit deny, the second and subsequent fragments do not hit the implicit permit rule for fragments. IP fragments ACL When a packet exceeds the maximum packet size, the packet is fragmented into a number of smaller packets that contain portions of the contents of the original packet. This packet flow begins with an initial packet that contains all of the Layer 3 (L3) and Layer 4 (L4) header information contained in the original packet, and is followed by a number of packets that contain only the L3 header information. This packet flow contains all of the information from the original packet distributed through packets that are small enough to avoid the maximum packet size limit. This provides a particular problem for ACL processing. If the ACL filters based on L4 information, the non-initial packets within the fragmented packet flow will not match the L4 information, even if the original packet would have matched the filter. Because of this filtering, packets are not processed by the ACL. Access Control Lists 373