seq (rules in IPv4 extended
bACLs)
Inserts filtering rules in IPv4 extended
ACLs crafted as IP broadcast ACLs (bACLs).
Syntax
seq
seq-value
{
permit
|
deny
}
ip-protocol
{
S_IPaddress
mask
|
host
S_IPaddress
|
any
}
[
source-operator
[
S_port-numbers
]
]
[
TCP-flags
]
[
vlan
vlanID
]
[
count
]
{
permit
|
deny
}
ip-protocol
{
S_IPaddress
mask
|
host
S_IPaddress
|
any
}
[
source-operator
[
S_port-numbers
]
]
[
TCP-flags
]
[
count
]
[
vlan
vlanID
]
no
{
permit
|
deny
}
ip-protocol
{
S_IPaddress
mask
|
host
S_IPaddress
|
any
}
[
source-operator
[
S_port-numbers
]
]
[
TCP-flags
]
[
vlan
vlanID
]
[
count
]
Parameters
- seq
- (Optional) Enables you to assign a sequence number to the rule. If you do not specify
seq
seq-value, the rule is added at the end of the list.
- seq-value
- Valid values range from 1 through 65535.
- permit
- Specifies rules to permit traffic.
- deny
- Specifies rules to deny traffic.
-
hard-drop
- For bACLs, equivalent to deny.
- ip-protocol
- Indicates the type of IP packet you are filtering. The options are as follows:
- <0-255>
- Protocol number custom value from 0 through 255.
- icmp
- Internet Control Message Protocol
- ip
- Any IP protocol
- tcp
- (Supported only if the containing ACL is applied to incoming traffic) Transmission Control Protocol
- udp
- User Datagram Protocol
- S_IPaddress
- Specifies a source address for which you want to filter the subnet.
- mask
- Defines a mask, whose effect is to specify a subnet that includes the source address that you specified. For options to specify the mask, see the Usage Guidelines.
- host
- Specifies a source address.
- S_IPaddress
- The source address.
- any
- Specifies all source addresses.
- source-operator
- If you specified
tcp or
udp
ip-protocol, the following optional operators are available:
- eq
- The policy applies to the TCP or UDP port name or number you enter after
eq.
- gt
- The policy applies to TCP or UDP port numbers equal to or greater than the port number or the numeric equivalent of the port name you enter after
gt.
- lt
- The policy applies to TCP or UDP port numbers that are equal to or less than the port number or the numeric equivalent of the port name you enter after
lt.
- neq
- The policy applies to all TCP or UDP port numbers except the port number or port name you enter after
neq.
- range
- The policy applies to all TCP or UDP port numbers that are between the first TCP or UDP port name or number and the second one you enter following the
range keyword. The range includes the port names or numbers you enter. For example, to apply the policy to all ports between and including 23 (Telnet) and 53 (DNS), enter the following: range 23 53 (two values separated by a space). The first port number in the range must be lower than the last number in the range.
- S_port-numbers
- (Valid only when
ip-protocol is UDP or TCP) Specifies one or more source or destination port numbers.
- vlan
vlanID
- Specifies a VLAN interface to which the ACL is bound.
- TCP-flags
- If you specify tcp
ip-protocol, one or more of the following flags are
available:
- ack
- Filters packets
for which the ack
(acknowledge) flag is set.
- fin
- Filters packets
for which the fin
(finish) flag is set.
- rst
- Filters packets
for which the rst
(reset) flag is set.
- sync
- Filters packets
for which the syn
(synchronize) flag is set.
- urg
- Filters packets
for which the urg
(urgent) flag is set.
- push
- Filters packets
for which the psh
(push) flag is set.
- count
- Enables statistics for the rule.
- log
- Not supported for bACLs.
- mirror
- Not supported for bACLs.
- copy-sflow
- Not supported for bACLs.
Modes
ACL configuration mode
Usage Guidelines
This topic describes filtering rules in an extended IPv4 ACL intended for use as an
IP broadcast ACL (bACL).
Broadcast ACLs are not supported on SLX 9150 or SLX 9250
devices.
The order of the rules in an ACL is critical, as the first matching rule stops further processing. When creating rules, specifying sequence values determines the order of rule processing. If you do not specify a sequence value, the rule is added to the end of the list.
You can specify a mask in either of the following ways:
- Wildcard mask format—for example, 0.0.0.255. The advantage of this format is that it enables you mask any bit, for example by specifying 0.255.0.255.
- Classless Interdomain Routing (CIDR) format—in which you specify the number of bits of the prefix. For example, appending /24 to an IPv4 address is equivalent to specifying 0.0.0.255 as wildcard mask format.
To delete a rule from an ACL, do the relevant of the following:
- If you know the rule number, enter
no seq
seq-value.
- If you do not know the rule number, type
no followed by the full syntax without
seq
seq-value.
Examples
The following example creates an IPv4 extended
bACL, defines rules for it, and applies the bACL to an interface.
device# configure
device(config)# ip access-list extended bACL_ext_12
device(conf-ipacl-ext)# seq 5 deny tcp host 10.24.26.145 any eq 23
device(conf-ipacl-ext)# seq 7 deny tcp any any eq 80
device(conf-ipacl-ext)# seq 10 deny udp any any range 10 25
device(conf-ipacl-ext)# seq 15 permit tcp any any
device(conf-ipacl-ext)# exit
device(config)# interface ethernet 0/6
device(conf-if-eth-0/6)# ip subnet-broadcast-acl bACL_ext_12
The following example creates an IPv4 extended bACL, defines rules for it, and
applies the bACL at device level.
device# configure
device(config)# ip access-list extended bACL_ext_22
device(conf-ipacl-ext)# seq 5 deny tcp host 10.24.26.145 any eq 23
device(conf-ipacl-ext)# seq 7 deny tcp any any eq 80
device(conf-ipacl-ext)# seq 10 deny udp any any range 10 25
device(conf-ipacl-ext)# seq 15 permit tcp any any
device(conf-ipacl-ext)# exit
device(config)# ip global-subnet-broadcast-acl bACL_ext_22
