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  1. #1
    Master Untangler
    Join Date
    Jan 2011
    Posts
    110

    Default Running out of LAN IPs

    Our school is using Untangle on a network 192.168.10.1-255. It uses the standard 255.255.255.0 subnet. We have 7 unmanaged switches, all 24 port gigabit.

    Over time we are gradually running low on available IPs in this range. This is mainly due to increasing mobile devices, small network printers, etc.

    I have read that the simplest way to give us more available IPs is switching the subnet to 255.255.254.0, which I believe would double us up to 512 available IP addresses. Then we could put network printers on the new IP range to free up extra slots in our primary range.

    However, other than having to make the ".255 to .254" subnet change in Untangle and any other device in the network running Static, is there any other problems this would cause, or anything else that would need to be done? Anything Untangle would have issue with?

    ps: If our existing range is 192.168.10.x, and we changed to .254 subnet..... would our new IP range become 192.168.11.x?


    Thanks!

  2. #2
    Untangle Ninja mrunkel's Avatar
    Join Date
    Jul 2008
    Posts
    3,022

    Default

    No, your new IP subnet is 192.168.10.0/23 instead of 192.168.10.0/24. The network portion is unchanged, you're just moving one bit from the network portion to the host portion.

    Luckily for you, that bit was 0 to start with. If you're starting network was 192.168.11.0/24, then changing it to a /23 would require that the network address be 192.168.10.0/23 since there is no way to have a 192.168.11.0/23 network (This makes sense if you think about the address in binary).

    Changing the subnet mask all all devices is important, but not technically required as long as the Untangle can get there.

    Your old network:

    Code:
    Marcs-iMac:~ mrunkel$ ipcalc 192.168.10.1/24
    
    Address:   192.168.10.1          11000000.10101000.00001010 .00000001
    Netmask:   255.255.255.0 == 24   11111111.11111111.11111111 .00000000
    Wildcard:  0.0.0.255             00000000.00000000.00000000 .11111111
    =>
    Network:   192.168.10.0/24       11000000.10101000.00001010 .00000000 (Class C)
    Broadcast: 192.168.10.255        11000000.10101000.00001010 .11111111
    HostMin:   192.168.10.1          11000000.10101000.00001010 .00000001
    HostMax:   192.168.10.254        11000000.10101000.00001010 .11111110
    Hosts/Net: 254                   (Private Internet RFC 1918)
    Your new network:

    Code:
    Marcs-iMac:~ mrunkel$ ipcalc 192.168.10.1/23
    
    Address:   192.168.10.1          11000000.10101000.0000101 0.00000001
    Netmask:   255.255.254.0 == 23   11111111.11111111.1111111 0.00000000
    Wildcard:  0.0.1.255             00000000.00000000.0000000 1.11111111
    =>
    Network:   192.168.10.0/23       11000000.10101000.0000101 0.00000000 (Class C)
    Broadcast: 192.168.11.255        11000000.10101000.0000101 1.11111111
    HostMin:   192.168.10.1          11000000.10101000.0000101 0.00000001
    HostMax:   192.168.11.254        11000000.10101000.0000101 1.11111110
    Hosts/Net: 510                   (Private Internet RFC 1918)
    For those that are interested, I've attached the script that generates that output.
    Last edited by mrunkel; 05-21-2012 at 11:25 AM.
    m.
    <BR>
    Big Frickin Disclaimer:
    While I'm pretty sure, I can't guarantee that I know what I'm doing. There might be a better way to do this, and this way might actually suck. Make sure you understand the implications of what you're doing before trying to follow these directions.
    <BR>It often helps troubleshooting if you have a good network map. Look <A HREF="http://forums.untangle.com/tip-day/5407-how-draw-network-diagram.html">here</A> if you want my advice on how to draw one. <BR> <B>Attention: Support and help on the Untangle Forums is provided by volunteers and community members like yourself.
    If you need Untangle support please call or email support@untangle.com<B>

  3. #3
    Master Untangler
    Join Date
    Jan 2011
    Posts
    110

    Default

    Thanks mrunkel,
    Wow, okay so I got a bit lucky then when choosing the network years ago.

    So, if I were to make the subnet change as outlined above, can you give me a quick yes/no for the following things:

    a)I would instantly have available to me the new range of: 192.168.10.1-192.168.11.255

    b)I could in theory leave my current devices with static IPs on a netmask of 255.255.255.0 and they would work, but important to change them to 255.255.254.0 regardless.

    c)In a perfect world I would only have to change the netmask in Untangle to 255.255.254.0 and nothing more.

    d)In this perfect world, I could change Untangle DHCP Server to start handing out a START/STOP in the 192.168.11.x range.

    e)In my Untangle policy manager, my schedules for virtual racks that have existing clients specified in my old IP range would still be active.

    f)using the "ANY" option for client address in the policy manager would also include the new 192.168.11.x range as well.

    Thanks for the help! I am trying to uncover any potential snags here before attempting a change.

  4. #4
    Untangle Ninja mrunkel's Avatar
    Join Date
    Jul 2008
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    3,022

    Default

    Quote Originally Posted by bluesky View Post
    Thanks mrunkel,
    Wow, okay so I got a bit lucky then when choosing the network years ago.

    So, if I were to make the subnet change as outlined above, can you give me a quick yes/no for the following things:

    a)I would instantly have available to me the new range of: 192.168.10.1-192.168.11.255
    Yes
    b)I could in theory leave my current devices with static IPs on a netmask of 255.255.255.0 and they would work, but important to change them to 255.255.254.0 regardless.
    Yes, they "should" work, but you'll have very poor performance.
    c)In a perfect world I would only have to change the netmask in Untangle to 255.255.254.0 and nothing more.
    Not sure what that means. All devices in the network should reflect the correct network settings.
    d)In this perfect world, I could change Untangle DHCP Server to start handing out a START/STOP in the 192.168.11.x range.
    Yes, the range now available will be 192.168.10.1 - 192.168.11.254.
    e)In my Untangle policy manager, my schedules for virtual racks that have existing clients specified in my old IP range would still be active.
    Yes, they won't be affected.
    f)using the "ANY" option for client address in the policy manager would also include the new 192.168.11.x range as well.
    Yes, any means any.
    Thanks for the help! I am trying to uncover any potential snags here before attempting a change.
    marvosa and bluesky like this.
    m.
    <BR>
    Big Frickin Disclaimer:
    While I'm pretty sure, I can't guarantee that I know what I'm doing. There might be a better way to do this, and this way might actually suck. Make sure you understand the implications of what you're doing before trying to follow these directions.
    <BR>It often helps troubleshooting if you have a good network map. Look <A HREF="http://forums.untangle.com/tip-day/5407-how-draw-network-diagram.html">here</A> if you want my advice on how to draw one. <BR> <B>Attention: Support and help on the Untangle Forums is provided by volunteers and community members like yourself.
    If you need Untangle support please call or email support@untangle.com<B>

  5. #5
    Master Untangler
    Join Date
    Jan 2009
    Location
    Minneapolis, MN
    Posts
    169

    Default

    You have a subnet of 254 IP's and only 168 ethernet connections... how are you running out of IP's?

    e.g.. Subnet your wireless traffic, subnet your IP phones, you could even subnet each floor... It sounds like an improved network design is what you need vs. a netmask "bandaid"...

    What happens in a few years when you run out of IP's again... go to a /22 and have 1000 devices on the same broadcast domain?
    SidSid and Scott B like this.

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