Users Guide

Conguring Filters Without a Sequence Number
If you are creating an extended ACL with only one or two lters, you can let Dell Networking OS assign a sequence number based on
the order in which the lters are congured. Dell Networking OS assigns lters in multiples of ve.
To congure a lter for an extended IP ACL without a specied sequence number, use any or all of the following commands:
• Congure a deny or permit lter to examine IP packets.
CONFIG-EXT-NACL mode
{deny | permit} {source mask | any | host ip-address} [count [byte]] [order] [monitor]
[fragments]
• Congure a deny or permit lter to examine TCP packets.
CONFIG-EXT-NACL mode
{deny | permit} tcp {source mask] | any | host ip-address}} [count [byte]] [order]
[monitor] [fragments]
• Congure a deny or permit lter to examine UDP packets.
CONFIG-EXT-NACL mode
{deny | permit} udp {source mask | any | host ip-address}} [count [byte]] [order]
[monitor] [fragments]
When you use the log keyword, the CP logs details about the packets that match. Depending on how many packets match the log
entry and at what rate, the CP may become busy as it has to log these packets’ details.
The following example shows an extended IP ACL in which the software assigned the sequence numbers. The lters were assigned
sequence numbers based on the order in which they were congured (for example, the rst lter was given the lowest sequence
number). The show config command in IP ACCESS LIST mode displays the two lters with the sequence numbers 5 and 10.
Example of Viewing Filter Sequence for a Specied Extended ACL
Dell(config-ext-nacl)#deny tcp host 123.55.34.0 any
Dell(config-ext-nacl)#permit udp 154.44.123.34 0.0.255.255 host 34.6.0.0
Dell(config-ext-nacl)#show config
!
ip access-list extended nimule
seq 5 deny tcp host 123.55.34.0 any
seq 10 permit udp 154.44.0.0 0.0.255.255 host 34.6.0.0
Dell(config-ext-nacl)#
To view all congured IP ACLs and the number of packets processed through the ACL, use the show ip accounting access-
list
command in EXEC Privilege mode, as shown in the rst example in Congure a Standard IP ACL.
Established Flag
To obtain the functionality of est, use the following ACLs.
• permit tcp any any rst
• permit tcp any any ack
Congure Layer 2 and Layer 3 ACLs
You can congure both Layer 2 and Layer 3 ACLs on an interface in Layer 2 mode.
If both L2 and L3 ACLs are applied to an interface, the following rules apply:
• When Dell Networking OS routes the packets, only the L3 ACL governs them because they are not ltered against an L2 ACL.
• When Dell Networking OS switches the packets, rst the L3 ACL lters them, then the L2 ACL lters them.
Access Control Lists (ACLs)
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