Dell Force10 MXL Blade - Configure a Standard IP ACL

76 | Access Control Lists (ACLs)
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Configure a Standard IP ACL
To configure an ACL, use commands in IP ACCESS LIST mode and INTERFACE mode. For a complete
listing of all commands related to IP ACLs, refer to the FTOS 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.
To configure a standard IP ACL, follow these steps:
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 (Figure 5-6).
Note the following when configuring ACLs with the fragments keyword.
When an ACL filters packets, it looks at the fragment offset (FO) to determine whether or not it is a fragment.
FO = 0 means it is either the first fragment or the packet is a non-fragment.
FO > 0 means it is dealing with the fragments of the original packet.
Permit ACL line with L3 information only and the fragments keyword is present:
If a packet's L3 information matches the L3 information in the ACL line, the packet's fragment offset (FO) is
checked.
•If a packet's FO > 0, the packet is permitted.
•If a packet's FO = 0, the next ACL entry is processed.
Deny ACL line with L3 information only and the fragments keyword is present:
If a packet’s L3 information matches the L3 information in the ACL line, the packet's fragment offset (FO) is
checked.
•If a packet's FO > 0, the packet is denied.
•If a packet's FO = 0, the next ACL line is processed.
Step Command Syntax Command Mode Purpose
1
ip access-list standard access-listname
CONFIGURATION Enter IP ACCESS LIST mode by
naming a standard IP access list.
2
seq sequence-number {deny | permit} {source
[mask] | any | host ip-address} [count [byte]]
[order] [fragments]
CONFIG-STD-NACL Configure a drop or forward filter.
Note: When assigning sequence numbers to filters, you might need to insert a new filter. To
prevent reconfiguring multiple filters, assign sequence numbers in multiples of five or another
number.