Dell Command Line Reference Guide for the S4048–ON System


permit tcp (for IPv6 ACLs)

Configure a filter to pass TCP packets that match the filter criteria.

permit tcp {source address mask | any | host ipv6-address} [operator port [port]] {destination address | any | host ipv6-address} [bit] [operator port [port]] [ttl operator] [count [byte]] [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 permit tcp {source address mask | any | host ipv6-address} {destination address | any | host ipv6-address} command.
source address mask
Enter a network mask in /prefix format (/x).
Enter the keyword any to specify that all routes are subject to the filter.
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.
Enter a flag or combination of bits:
  • ack: acknowledgement field
  • fin: finish (no more data from the user)
  • psh: push function
  • rst: reset the connection
  • syn: synchronize sequence numbers
  • urg: urgent field
(OPTIONAL) Enter one of the following logical operand:
  • eq = equal to
  • neq = not equal to
  • gt = greater than
  • lt = less than
  • range = inclusive range of ports (you must specify two ports for the port parameter)
port port
Enter the application layer port number. Enter two port numbers if you are using the range logical operand. The range is from 0 to 65535.
The following list includes some common TCP port numbers:
  • 23 = Telnet
  • 20 and 21 = FTP
  • 25 = SMTP
  • 169 = SNMP
Enter the keyword ttl to permit a packet based on the time to live value. The range is from 1 to 255.
Enter one of the following logical operand:
  • eq(equal to) — matches packets that contain a ttl value that is equal to the specified ttl value.
  • neq(not equal to) — matches packets that contain a ttl value that is not equal to the specified ttl value.
  • gt(greater than) — matches packets that contain a ttl value that is greater than the specified ttl value.
  • lt (less than) — matches packets that contain a ttl value that is less than the specified ttl value.
  • range(inclusive range of values) — matches packets that contain a ttl value that falls between the specified range of ttl values.
(OPTIONAL) Enter the keyword count to count packets the filter processes.
(OPTIONAL) Enter the keyword byte to count bytes the filter processes.
(OPTIONAL) Enter the keyword log to enable the triggering of ACL log messages.
threshold-in msgs count
(OPTIONAL) Enter the threshold-in-msgs keyword followed by a value to indicate the maximum number of ACL logs that can be generated, exceeding which the generation of ACL logs is terminated. with the seq, permit, or deny commands. The threshold range is from 1 to 100.
interval minutes
(OPTIONAL) Enter the keyword interval followed by the time period in minutes at which ACL logs must be generated. The interval range is from 1 to 10 minutes.
(OPTIONAL) Enter the keyword monitor when the rule is describing the traffic that you want to monitor and the ACL in which you are creating the rule is applied to the monitored interface.

By default, 10 ACL logs are generated if you do not specify the threshold explicitly.

The default frequency at which ACL logs are generated is 5 minutes. By default, flow-based monitoring is not enabled.

Command Modes
Command History

This guide is platform-specific. For command information about other platforms, see the relevant Dell EMC Networking OS Command Line Reference Guide.

Introduced the ttl parameter.
Added the established parameter on the S6000, S6000–ON, S6100–ON, Z9100–ON.
Introduced on the S6010-ON and S4048T-ON.
Introduced on the S3148.
Introduced on the S6100.
Introduced on the S3100 series.
Introduced on the Z9100–ON.
Introduced on the S4048-ON.
Introduced on the S3048-ON.
Introduced on the S6000–ON.
Introduced on the Z9500.
Added support for flow-based monitoring on the S4810, S4820T, S6000, and Z9000 platforms.
Added support for logging of ACLs on the S4810, S4820T, and Z9000 platforms.
Usage Information

When the configured maximum threshold is exceeded, generation of logs is stopped. When the interval at which ACL logs are configured to be recorded expires, the subsequent, fresh interval timer is started and the packet count for that new interval commences from zero. If ACL logging was stopped previously because the configured threshold is exceeded, it is re-enabled for this new interval.

If ACL logging is stopped because the configured 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 configure 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).

Related Commands
  • permit – assign a permit filter for IP packets.

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