Using Authorized IP Managers
Building IP Masks
IP list. Thus, in the example shown above, a “255” in an IP Mask octet (all bits
in the octet are “on”) means only one value is allowed for that octet—the value
you specify in the corresponding octet of the Authorized Manager IP list. A “0”
(all bits in the octet are “off”) means that any value from 0 to 255 is allowed
in the corresponding octet in the IP address of an authorized station. You can
also specify a series of values that are a subset of the 0-255 range by using a
value that is greater than 0, but less than 255.
Table 14-2. Analysis of IP Mask for Multiple-Station Entries
1st
Octet
2nd
Octet
3rd
Octet
4th
Octet
Manager-Level or Operator-Level Device Access
IP Mask
Authorized
Manager IP
255
10
IP Mask
Authorized
IP Address
255
10
255 255 0 The “255” in the first three octets of the mask specify that only the exact
28 227 125
value in the octet of the corresponding IP address is allowed. However,
the zero (0) in the 4th octet of the mask allows any value between 0 and
255 in that octet of the corresponding IP address. This mask allows switch
access to any device having an IP address of 10.28.227.xxx, where xxx is
any value from 0 to 255.
255 255 249 In this example (figure 14-3, below), the IP mask allows a group of up to
28 227 125
4 management stations to access the switch. This is useful if the only
devices in the IP address group allowed by the mask are management
stations. The “249” in the 4th octet means that bits 0 and 3 - 7 of the 4th
octet are fixed. Conversely, bits 1 and 2 of the 4th octet are variable. Any
value that matches the authorized IP address settings for the fixed bits is
allowed for the purposes of IP management station access to the switch.
Thus, any management station having an IP address of 10.28.227.121
, 123,
125
, or 127 can access the switch.
14-11
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