Services: DHCP server ip range round the wrong way.
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2.2-RELEASE (amd64)
built on Thu Jan 22 14:03:54 CST 2015Services: DHCP
Subnet Mask Available range
255.255.255.255 /32 x.x.x.250 - x.x.x.248 Are these two the right way round?
255.255.255.254 /31 x.x.x.249 - x.x.x.248 Are these two the right way round?
255.255.255.252 /30 x.x.x.249 - x.x.x.250TIA.
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masks of 32 and 31 would not be viable masks on a dhcp scope..
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Should the GUI allow it?
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Those are valid for setting the IP on your interface.. But not going to work with a dhcp scope on that interface.
See attached.. Guess they could put in some check to invalidate dhcp scope when address on interface set with those sorts of masks..
A mask of /32 is 1 address.. That specific address.. there is no IPs available at all for a dhcp server to hand out.. /31 is kind of special mask that could be used on point to point connections between say 2 routers for a transit network where 1 side had 192.168.1.2/31 and other hand 192.168.1.3/31 or .0 and .1 – but again that would not be valid for use with dhcp.
Smallest scope would be /30
So for example 192.168.1.0 would be the wire, .1 would be the interface and .2 would be 1 address available and .3 would be broadcast.
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/32 is the default mask for a new nic so I wonder if it might cause some problems for new users, thats where I am coming from.
Is there any reason for /32 to be the default for a new nic?
Any advantages/disadvantages in changing the default to say /30 or even /24, to avoid dhcp scoping issues?Depends on the target audience I guess, although I see advantages in using small ip address ranges.
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If users do not understand what the mask to set on their interface they really should not be creating new interfaces ;)
/32 is not the default to be honest, that is just the first item in the drop list you can pick from.. Should they have the list sorted the other direction and make it /1 ?
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If users do not understand what the mask to set on their interface they really should not be creating new interfaces ;)
Its another thing to be aware of as its changed behaviour from earlier versions, I saw it and wondered what it would do to the dhcp page more than anything else, but irrespective of above, I reckon given time it will trip a few users up.
/32 is not the default to be honest, that is just the first item in the drop list you can pick from.. Should they have the list sorted the other direction and make it /1 ?
I dont think reversing the sort order is neccesary, but it would be useful if it could default to a common subnet mask imo.
Sometimes common configuration mistakes can become exploitable and whilst I dont expect this to be a problem, I dont know what else it might cause problems for. Until I poke around a bit more it might be just a blind alley and nothing to worry about.
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"but it would be useful if it could default to a common subnet mask imo."
And who says what is common.. is /24 common? Maybe to you - but to others maybe they always use /25 when bringing up a new segment.. You have no idea what a user might be creating a interface for.. To assume /24 solves nothing - if the user doesn't understand what the mask is in the first place..
Put in a feature request if you would like the drop down to start on /24 for new interfaces for ipv4, and /64 for ipv6 since drop down on that one is /128
