Netopia R2121, User Reference Manual

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14-8 User’s Reference Guide
Port numbers
A filter can also match a packet’s por t number attributes, but only if the filter’s protocol type is set to TCP or
UDP, since only those protocols use por t numbers. The filter can be configured to match the following:
■
The source por t number (the por t on the sending host that originated the packet)
■
The destination por t number (the por t on the receiving host that the packet is destined for)
By matching on a por t number, a filter can be applied to selected TCP or UDP ser vices, such as Telnet, FTP, and
World Wide Web. The tables below show a few common ser vices and their associated por t numbers..
Port number comparisons
A filter can also use a comparison option to evaluate a packet’s source or destination por t number. The
comparison options are:
No Compare: No comparison of the por t number specified in the filter with the packet’s por t number.
Not Equal To: For the filter to match, the packet’s por t number cannot equal the por t number specified in the
filter.
Less Than: For the filter to match, the packet’s por t number must be less than the por t number specified in the
filter.
Less Than or Equal: For the filter to match, the packet’s por t number must be less than or equal to the por t
number specified in the filter.
Equal: For the filter to match, the packet’s por t number must equal the por t number specified in the filter.
Greater Than: For the filter to match, the packet’s por t number must be greater than the por t number specified
in the filter.
Internet service TCP port Internet service TCP port
FTP 20/21 Finger 79
Telnet 23 World Wide Web 80
SMTP (mail) 25 News 144
Gopher 70 rlogin 513
Internet service UDP port Internet service UDP port
Who Is 43 AppleTalk Routing
Maintenance (at-r tmp) 202
World Wide Web 80 AppleTalk Name Binding
(at-nbp) 202
SNMP 161 AURP (AppleTalk) 387
TFTP 69 who 513