From: Scott Morris (swm@emanon.com)
Date: Sun Apr 17 2005 - 09:17:10 GMT-3
That would permit all EVEN numbers in the third octet.
You need to remember that whatever you put in the "network" portion of your
acl is what SETS the starting point for your bits. Then your mask
determines whether each bit is a "don't care" or "stay the same". Right
now, you set all bits in the third octet to be a "0" value, then told the
least significant bit there to stay the same by putting a 0 in the mask.
Scott
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of Lee
Donald
Sent: Sunday, April 17, 2005 8:00 AM
To: 'Anthony Liu'; Lee Donald; ccielab@groupstudy.com
Subject: RE: Access-list question - Allowing even and odd numbers in 3rd
octet -
Anthony,
I'm using 0.0.0.0 255.255.254.255
And it is working fine.
I still don't understand really.
According to my access-list, as I understand it with my suffering brain, is
that the 255.255.254.255 means don't care about the first 2nd or 4th octet,
also don't care about 254 bits of the 3rd, but I do care about the last bit
in the 3rd, does that sound right?
What would be the correct access-list to just allow evens in the 3rd octet?
That might get it into my skull!
-----Original Message-----
From: Anthony Liu [mailto:zodiak@hawaii.rr.com]
Sent: Sunday, April 17, 2005 12:40 PM
To: Lee Donald; ccielab@groupstudy.com
Subject: RE: Access-list question - Allowing even and odd numbers in 3rd
octet -
If you want to permit all odds in the 3rd octet, it should be :
Access-list 5 permit 0.0.1.0 0.0.254.0
I've never been good at explaining ACL's but i'll try anyways ;)
The reason being, is as long as the 8th value of the third octet is 1, the
number will be odd, indicated by the 1(00000001) in the 3rd octect of the
first number. The second number determines which values to change, and
which to remain constant(1's representing wildcard's, and 0's representing
constants)... in this case the 254 in binary is 11111110, meaning the first
7 values can change in the first number, but not the 8'th(which will keep
the number odd) allowing all possible odds.
Anthony
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com]On Behalf Of Lee
Donald
Sent: Sunday, April 17, 2005 1:13 AM
To: ccielab@groupstudy.com
Subject: Access-list question - Allowing even and odd numbers in 3rd octet -
Can anyone put some more logic to this for me, I'm having a bad brain day.
I need to allow all odd numbers in the 3rd octet in via an access-list which
I know is
Access-list 5 permit 0.0.0.0 0.0.252.0
Then I tried to let just the evens in but got confused, and couldn't get my
dough brain round it.
Can anybody remind me of this and the way it works?
Thanks in advance.
Regards
Lee.
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