DHCP Subnet Mask wrong with \23 subnet

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sky7176
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Joined: August 13th, 2014, 9:21 am

DHCP Subnet Mask wrong with \23 subnet

Post by sky7176 » June 19th, 2017, 3:18 pm

Good evening,
I'm running an ipfire updated at 111.

It works from dhcp server.
I need to expand the masc subnet from a \ 24 to a \ 23.
I modified the ip of ipfire to 255.255.254.0 but I noticed that the dhcp server releases it as SM 255.255.255.0.

Currently the firewall address is 192.168.141.4 with SM 255.255.254.0, the subnet expansion will have as addresses from 192.168.140.0 to 192.168.141.255.

After the whole network is upgraded, the Firewall will therefore move as DCHP address as 192.168.140.1

DHCP will have to issue addresses in the range 192.168.141.1 to 192.168.141.254

Where am I wrong?

Many thanks

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Arne.F
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Re: DHCP Subnet Mask wrong with \23 subnet

Post by Arne.F » June 20th, 2017, 10:31 am

The DHCP Server not get the subnet mask from the host. It need to be configured on the DHCP config page.
Arne

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sky7176
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Joined: August 13th, 2014, 9:21 am

Re: DHCP Subnet Mask wrong with \23 subnet

Post by sky7176 » June 20th, 2017, 12:15 pm

Arne.F wrote:The DHCP Server not get the subnet mask from the host. It need to be configured on the DHCP config page.
Sorry, but in a dhcp server config I not have a setting for the subnet mask.
My DHCP Server release to client a wrong SM 255.255.255.0 but the subnet mask for the firewall is setting 255.255.254.0.

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Arne.F
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Re: DHCP Subnet Mask wrong with \23 subnet

Post by Arne.F » June 20th, 2017, 12:33 pm

Sorry. You are correct. Normal the dhcp config should take IP and subnet from the setup but if you change it, you have to go to the dhcp webcfg page and save the settings to take the new mask. If this not work there is a bug...
Arne

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sky7176
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Re: DHCP Subnet Mask wrong with \23 subnet

Post by sky7176 » June 20th, 2017, 3:39 pm

Good evening,
I did some tests, apparently if you have a subnet with mask \23, ipfire must be the first address of the entire subnet.
In this case, the subnet mask is passed to the clients correctly.
In practice, if I have a subnet that starts from 192.168.142.0 and goes up to 192.168.143.255 ipfire must have as green address 192.168.142.1 to let the dhcp server set the correct SM to the hosts.

If I'm wrong, let me know
Thank you

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Arne.F
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Re: DHCP Subnet Mask wrong with \23 subnet

Post by Arne.F » June 25th, 2017, 6:08 am

I cannot reproduce this. (I have used /23 and my fire is x.12)
Arne

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sky7176
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Re: DHCP Subnet Mask wrong with \23 subnet

Post by sky7176 » June 29th, 2017, 6:42 am

I don't know
Do you please extend the extension of your subnet?
For example from 192.168.12.0 to 192.168.13.255?
Because in my specific case I have the subnet extending from 192.168.12.0 to 192.168.13.255 and IPfire, as a result the DHCP server, has as address 192.168.13.4.
Thank you

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Arne.F
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Re: DHCP Subnet Mask wrong with \23 subnet

Post by Arne.F » July 10th, 2017, 9:16 am

My green IP is configured 192.168.12.1 and the netmask is 255.255.128.0
so i have the green net from 192.168.12.1 to 192.168.13.254 (Net Address is 192.168.12.0 and broadcast is 192.168.13.255)
and my dhcp server is 192.168.12.1
Arne

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