Users Guide

count for that new interval commences from zero. If ACL logging was stopped previously because the congured
threshold is exceeded, it is re-enabled for this new interval.
If ACL logging is stopped because the congured threshold is exceeded, it is re-enabled after the logging interval
period elapses. ACL logging is supported for standard and extended IPv4 ACLs, IPv6 ACLs, and MAC ACLs. You
can congure 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 ow-based monitoring for a monitoring session by entering the ow-based enable command in
the Monitor Session mode. When you enable this capability, trac with particular ows 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 specied trac instead all trac
on the interface. This feature is particularly useful when looking for malicious trac. It is available for Layer 2 and
Layer 3 ingress and egress trac. You may specify trac 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 (for IPv6 ACLs)
Congure a lter that drops TCP packets that match the lter criteria.
Syntax
deny tcp {source address mask | any | host ipv6-address} [operator port [port]]
{destination address | any | host ipv6-address} [bit] [operator port [port]]
[count [byte]] [log [interval minutes] [threshold-in-msgs [count]] [monitor]
To remove this lter, you have two choices:
• Use the no seq sequence-number command syntax if you know the lter’s sequence number
•
Use the no deny tcp {source address mask | any | host ipv6-address}
{destination address | any | host ipv6-address} command
Parameters
source address
mask
Enter a network mask in /prex format (/x).
any Enter the keyword any to specify that all routes are subject to the lter.
host ipv6-address Enter the keyword host then the IP address to specify a host IP address.
destination address Enter the IPv6 address of the network or host to which the packets are sent.
bit Enter a ag or combination of bits:
• ack: acknowledgement eld
• fin: nish (no more data from the user)
• psh: push function
• rst: reset the connection
• syn: synchronize sequence numbers
• urg: urgent eld
• established: datagram of established TCP session
Use the established ag to match only ACK and RST ags of established TCP
session.
You cannot use established along with the other control ags
Access Control Lists (ACL) 307