ACL logging only on ACLs that are applied to ingress interfaces; you cannot enable
logging for ACLs that are associated with egress interfaces.
You can activate flow-based monitoring for a monitoring session by entering the
flow-based enable
command in the Monitor Session mode. When you enable
this capability, traffic with particular flows that are traversing through the ingress
and egress interfaces are examined and, appropriate ACLs can be applied in both
the ingress and egress direction. Flow-based monitoring conserves bandwidth by
monitoring only specified traffic instead all traffic on the interface. This feature is
particularly useful when looking for malicious traffic. It is available for Layer 2 and
Layer 3 ingress and egress traffic. You may specify traffic using standard or
extended access-lists. This mechanism copies all incoming or outgoing packets on
one port and forwards (mirrors) them to another port. The source port is the
monitored port (MD) and the destination port is the monitoring port (MG).
deny tcp
Configure a filter that drops transmission control protocol (TCP) packets meeting the filter criteria.
Syntax
deny tcp {
source mask
| any | host
ip-address
} [
bit
] [
operator
port
[
port
]] {
destination mask
| any | host
ip-address
} [dscp]
[
bit
] [
operator port
[
port
]] [count [byte] [order] [fragments]
[log [interval minutes] [threshold-in-msgs [count]] [monitor]
To remove this filter, you have two choices:
• Use the
no seq
sequence-number
command if you know the filter’s
sequence number.
• Use the
no deny tcp {
source mask
| any | host
ip-address
}
{
destination mask
| any | host
ip-address
}
command.
Parameters
source
Enter the IP address of the network or host from which the
packets are sent.
mask
Enter a network mask in /prefix format (/x) or A.B.C.D. The
mask, when specified in A.B.C.D format, may be either
contiguous or non-contiguous.
any
Enter the keyword
any
to specify that all routes are subject
to the filter.
host
ip-address
Enter the keyword
host
then the IP address to specify a host
IP address.
dscp
Enter this keyword
dscp
to deny a packet based on the
DSCP value. The range is from 0 to 63.
bit
Enter a flag or combination of bits:
•
ack:
acknowledgement field
Access Control Lists (ACL)
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