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Access List for Cisco # 2

Hi,

1) There are the following access list which i am still getting confused (for some portion) (and i do not have the "practice labs" to try it
2)The information is as the followings:
- The Host IP : 192.168.1.128/28
- The Server is 192.168.1.5
- The Goal : To block only Telnet access by the Host to the Server
- The Access list: i) access-list 101 deny tcp 192.168.1.128 0.0.0.15 192.168.1.5 0.0.0.0 eq 23,
ii) access-list 101 permit ip any any

3) The things that i do not understand: i) ...... 192.168.1.5 0.0.0.0 .....
4) My Question: i) Why is ....0.0.0.0 ? (Why NOT .....0.0.0.15?)
5) Any help?
6) Thank you

Tjie

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kyleb84

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ionut_mir

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kyleb84

"If you put 0.0.0.15 this access-list will deny any IP from range 192.168.1.0 - 128"

A single wildcard value that blocks 0-128, and allows the rest isn't possible, since the bit to make 128 is the eighth (1000 0000) and therefore would block the entire 0-255 range when put with the rest to block 0-127 (0111 1111)

.15 as the author wrote is /28 and only matches 16 addresses