Users Guide

Congure Filters, UDP Packets
To create a lter for UDP packets with a specied sequence number, use the following commands.
1 Create an extended IP ACL and assign it a unique name.
CONFIGURATION mode
ip access-list extended access-list-name
2 Congure an extended IP ACL lter for UDP packets.
CONFIG-EXT-NACL mode
seq sequence-number {deny | permit} tcp {source mask | any | host ip-address} [count [byte]]
[order] [fragments]
Example of the seq Command
When you create the lters with a specic sequence number, you can create the lters in any order and the lters are placed in the correct
order.
NOTE: When assigning sequence numbers to lters, you may have to insert a new lter. To prevent reconguring multiple lters,
assign sequence numbers in multiples of ve or another number.
The example below shows how the seq command orders the lters according to the sequence number assigned. In the example, lter 15
was congured before lter 5, but the
show config command displays the lters in the correct order.
Dell(config-ext-nacl)#seq 15 deny ip host 112.45.0.0 any log
Dell(config-ext-nacl)#seq 5 permit tcp 12.1.3.45 0.0.255.255 any
Dell(config-ext-nacl)#show confi
!
ip access-list extended dilling
seq 5 permit tcp 12.1.0.0 0.0.255.255 any
seq 15 deny ip host 112.45.0.0 any log
Dell(config-ext-nacl)#
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] [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] [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] [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 sequence numbers were assigned by the software. 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.
Access Control Lists (ACLs)
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