Справочное Руководство для Netopia 430 s

Src. Port: The source por t to match. This is the por t on the sending 
host that originated the packet.

D. Port: The destination por t to match. This is the por t on the 
receiving host for which the packet is intended.

On?: Displays Yes when the filter is in effect or No when it is not.

Fwd: Shows whether the filter for wards (Yes) a packet or discards 
(No) it when there’s a match. 

Returning to our filtering rule example from above (see 

), 

look at how a rule is translated into a filter. Star t with the rule, then 
fill in the filter’s attributes:

1.

The rule you want to implement as a filter is:

Block all Telnet attempts that originate from the remote host 
199.211.211.17.

2.

The host 199.211.211.17 is the source of the Telnet packets 
you want to block, while the destination address is any IP 
address. How these IP addresses are masked determines what 
the final match will be, although the mask is not displayed in 
the table that displays the filter sets (you set it when you create 
the filter). In fact, since the mask for the destination IP address 
is 0.0.0.0, the address for Dest IP Addr could have been 
anything. The mask for Source IP Addr must be 
255.255.255.255 since an exact match is desired.

■

Source IP Addr = 199.211.211.17

■

Source IP address mask = 255.255.255.255

■

Dest IP Addr = 0.0.0.0

TCP

6

Transmission Control Protocol

UDP

17

User Datagram Protocol

Protocol

Number to use

Full name