From: Stephen C. Feldberg (scfeldberg@xxxxxxxxxxx)
Date: Fri Jan 11 2002 - 17:44:51 GMT-3
Peter,
I have come up with a different answer:
deny 144.160.32.0 15.13.94.255
deny 192.6.5.129 255.255.1.129
permit any
I agree with most of your first statement, with the exception of the third
octet
deny 144.160.42.0 15.13.80.255
Here is how I broke it down into 4 octets and their values:
144 10010000
151 10010111
154 10011010
157 10011101
---------------
00001111 = 15 ("don't care" about last four bits) becomes wildcard
value
10010000 = 144 (value of first four bits that "must match") becomes
network value
160 10100000
164 10100100
168 10101100
173 10101101
---------------
00001101 = 13
1010 0 = 160
Here is where we disagree:
52 00110100
58 00111010
106 01101010
122 01111010
---------------
01011110 = 94
0 1 0 = 32
0 00000000
0 00000000
-------------
11111111 = 255
00000000 = 0
My answer would be:
deny 144.160.32.0 15.13.94.255
I also disagree with the last two octets of your second statement:
deny 192.6.4.128 0.0.1.126
192 11000000
192 11000000
---------------
11111111 = 255
11000000 = 192
6 00000110
6 00000110
-------------
11111111 = 255
00000110 = 6
Here's where we disagree:
4 00000100
5 00000101
------------
00000001 = 1
00000101 = 5
129 10000001
131 10000011
133 10000101
135 10000111
137 10001001
139 10001011
141 10001101
...
253 11111101
255 11111111
---------------
10000001 = 129
1 1 = 129
My answer would be:
deny 192.6.5.129 255.255.1.129
AFAIK, this is the binary logic that applies to these scenarios.
Steve
----- Original Message -----
From: "Frei Peter" <Peter.Frei@delec.ch>
To: <ccielab@groupstudy.com>
Sent: Thursday, January 10, 2002 6:46 PM
Subject: Advanced Access-List
> Hello group
> from a PROin course
> Filter the following networks with a minimum of config statements:
> 157.173.52.0;144.160.58.0;151.168.122.0;154.164.106.0
>
> and filter all odd hosts from the networks 192.6.4.0/24,192.6.5.0/24
> beginning with host 192.6.4.128 and 192.6.5.128
>
>
> my solution
> ip access-list standard FILTERTask4
> deny 144.160.42.0 15.13.80.255
> deny 192.6.4.128 0.0.1.126
> permit any
>
> Any comments?
>
>
> Thanks
>
> Peter
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