Service Manual

Related Commands
• ip access-list extended — create an extended ACL.
•
• permit tcp — assign a permit lter for TCP packets.
• permit udp — assign a permit lter for UDP packets.
permit tcp
To pass TCP packets meeting the lter criteria, congure a lter.
Syntax
permit tcp {source mask | any | host ip-address} [bit] [operator port [port]]
{destination mask | any | host ip-address} [bit] [dscp] [operator port [port]]
[count [byte] [order] [fragments] [no-drop]
To remove this lter, you have two choices:
• Use the no seq sequence-number command if you know the lter’s sequence number.
•
Use the no permit 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 were sent.
mask Enter a network mask in /prex format (/x) or A.B.C.D. The mask, when specied 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 lter.
host ip-address Enter the keyword host then the IP address to specify a host IP address.
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
dscp Enter the keyword dscp to deny a packet based on the DSCP value. The range is from 0
to 63.
operator (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
208 Access Control Lists (ACL)