Dell S4820T, Configuration Manual

Page: 136 / 1178

Example of Logging Denied Packets
To log all the packets denied and to override the implicit deny rule and the implicit permit rule for TCP/
UDP fragments, use a configuration similar to the following.
Dell(conf)#ip access-list extended ABC
Dell(conf-ext-nacl)#permit tcp any any fragment
Dell(conf-ext-nacl)#permit udp any any fragment
Dell(conf-ext-nacl)# deny ip any any log
Dell(conf-ext-nacl)
When configuring ACLs with the fragments keyword, be aware of the following.
When an ACL filters packets, it looks at the fragment offset (FO) to determine whether 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.
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] [dscp] [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.
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
The following is an example of viewing the rules of a specific ACL on an interface.
Dell#show ip accounting access-list ToOspf interface gig 1/6
Standard IP access list ToOspf
seq 5 deny any
seq 10 deny 10.2.0.0 /16
seq 15 deny 10.3.0.0 /16
seq 20 deny 10.4.0.0 /16
seq 25 deny 10.5.0.0 /16
seq 30 deny 10.6.0.0 /16
seq 35 deny 10.7.0.0 /16
seq 40 deny 10.8.0.0 /16
seq 45 deny 10.9.0.0 /16
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Access Control Lists (ACLs)