To allow IPs from network 111.222.55.0 and 111.222.56.0 networks in TCP wrappers, what network and netmask pair can be used in /etc/hosts.allow?
Answer: 111.222.55.0/255.255.240.0
Explanation:
111.222.55.0 = 01101111.11011110.00110111.00000000
111.222.56.0 = 01101111.11011110.00111000.00000000
The common part of both networks is /20 which translates to 255.255.240.0If you use a more restrictive netmask (like /21, /22, …) you won’t be able to get both nets with one network and netmask pair.
From the man pages:
An expression of the form `n.n.n.n/m.m.m.m is interpreted as a `net/mask pair. An IPv4 host address is matched if `net is equal to the bitwise AND of the address and the `mask. For example, the net/mask pattern `131.155.72.0/255.255.254.0 matches every address in the range `131.155.72.0 through `131.155.73.255. `255.255.255.255 is not a valid mask value, so a single host can be matched just by its IP.
111.222.55.0 not network so 111.222.56.0 can`t include same subnetwork,
The correct answer should be 111.222.48.0/255.255.240.0 .
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I agree with James.
The correct answer is: 111.222.48.0/255.255.240.0
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it´s an ordinary way to verify the knowledgement about netmasks ..
Sincerly
toki
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oh, sorry about my typo ..
;-)
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