Example of Layer 4 ACL Rules
Example of TCP Packets
In this first example, fragments or non-fragmented TCP packets from 10.1.1.1 with TCP destination port
equal to 24 are permitted. All other fragments are denied.
Dell(conf)#ip access-list extended ABC
Dell(conf-ext-nacl)#permit tcp host 10.1.1.1 any eq 24
Dell(conf-ext-nacl)#deny ip any any fragment
Dell(conf-ext-nacl)
In the following example, TCP packets that are first fragments or non-fragmented from host 10.1.1.1 with
TCP destination port equal to 24 are permitted. Additionally, all TCP non-first fragments from host
10.1.1.1 are permitted. All other IP packets that are non-first fragments are denied.
Dell(conf)#ip access-list extended ABC
Dell(conf-ext-nacl)#permit tcp host 10.1.1.1 any eq 24
Dell(conf-ext-nacl)#permit tcp host 10.1.1.1 any fragment
Dell(conf-ext-nacl)#deny ip any any fragment
Dell(conf-ext-nacl)
Configure a Standard IP ACL
To configure an ACL, use commands in IP ACCESS LIST mode and INTERFACE mode.
For a complete list of all the commands related to IP ACLs, refer to the Dell Networking OS Command
Line Interface Reference Guide. To set up extended ACLs, refer to Configure an Extended IP ACL.
A standard IP ACL uses the source IP address as its match criterion.
1. Enter IP ACCESS LIST mode by naming a standard IP access list.
CONFIGURATION mode
ip access-list standard access-listname
2. Configure a drop or forward filter.
CONFIG-STD-NACL mode
seq sequence-number {deny | permit} {source [mask] | any | host ip-address}
[count [byte]] [order] [fragments]
NOTE: When assigning sequence numbers to filters, keep in mind that you might need to insert a
new filter. To prevent reconfiguring multiple filters, assign sequence numbers in multiples of five.
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.
To view the rules of a particular ACL configured on a particular interface, use the show ip accounting
access-list ACL-name interface interface command in EXEC Privilege mode.
Example of Viewing the Rules of a Specific ACL on an Interface
Example of the seq Command to Order Filters
Dell#show ip accounting access-list ToOspf interface gig 1/6
Standard IP access list ToOspf
114 Access Control Lists (ACLs)