Why do I get a warning that my /23 network is not tuned correctly? That is a perfectly normal.

I have a network with a 23 bit subnet mask.  I got a warning on the Desktop App on Mac that states it is not tuned correctly.  That is an inappropriate warning.  Perfectly normal configuration.

Answers

  • rooted
    rooted Gulf Coast, USModerator Posts: 892
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    Perhaps it means you need to specify the network size in Fing settings.

  • Robin_from_Fing
    Robin_from_Fing Administrator, Fing Team Posts: 5,052
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    admin
    Hi @InfoSec911
    Thanks for your post. If you click on the "question mark" icon, it will explain the meaning of this.
    Technical Information

    The check verifies that your network subnet mask (or network prefix length) is not oversized. Although networking standards recommend to always prefer multicast and broadcast when searching for networking services and devices, many modern IoT devices have still been using unicast sweeps to find peers: this means that lookup, onboarding, pairing or service usage when you have a big network will make the device lookup for the service on a very big number of possible devices, instead of just 256/512. A good example of this is also Windows workgroup: NetBIOS is unicast, so lookup of other PC and printers in a big network takes much longer. The same happens as well to network monitoring software like Fing, Fingbox, and so on: these apps leverage ARP-sweep or ping or similar, so the time taken by a network discovery is proportional to the network size.

    What it means for me

    A subnet mask is a number that defines the range of (IP) addresses available within a network. It uses the same format as IP address, but in negative format, e.g. 255.255.255.0 is a typical Class C mask including a range of 256 addresses. An alternate form to express it is as network prefix length, meaning how many bits of the network address are stable: a class C network is /24, meaning that 24 bits, first 3 bytes of the address, are not varying.

    How I can fix this

    An oversized network is much slower than a correctly sized one. E.g. a home network with dozen devices not being a Class C is definitely not tuned correctly. In order to fix it you don't have to change your local PC configuration but rather login into the router configuration and edit it. To make sure every device gets the new updated configuration you should also power cycle or reconnect all connected devices.

    Robin (Admin at Fing)
    Getting Started? Please refer to Community guidelines & Community User Guides. HAPPY POSTING!!!
    rooted
  • InfoSec911
    InfoSec911 Member Posts: 17
    10 Comments Photogenic
    Perhaps you could label it more correctly by saying it is not optimally configured, or something like that.  "Not Tuned Correctly" is incorrect.  It is configured correctly for my needs.
  • Robin_from_Fing
    Robin_from_Fing Administrator, Fing Team Posts: 5,052
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    Thanks for the feedback @InfoSec911
    I will share the feedback with our Developers. Thanks again.
    Robin (Admin at Fing)
    Getting Started? Please refer to Community guidelines & Community User Guides. HAPPY POSTING!!!
  • InfoSec911
    InfoSec911 Member Posts: 17
    10 Comments Photogenic
    May have to delete the app, unless I can turn off all the incorrect warnings I am getting.  Let the developers know they need to provide an option to turn off notifications unless they are correct!
  • Waldhaus2
    Waldhaus2 Member Posts: 5
    First Anniversary First Comment Photogenic
    I am confused because I don't know what the better tuned net mask would be. What should I change it to?
  • InfoSec911
    InfoSec911 Member Posts: 17
    10 Comments Photogenic
    In Fing's opinion, it appears that a /24 (24 bit subnet mask) is THE correctly tuned subnet mask and a /23 (23 bit subnet mask) is incorrect.  That is just not true.  /23 networks are used all over the place and are just NOT incorrect.  They may not be the common subnet mask used for home networks, but they are NOT incorrect.  You can call it out as a larger subnet than typical home networks (or something similar), but please do not call it incorrect, that is incorrect.
  • rooted
    rooted Gulf Coast, USModerator Posts: 892
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    edited March 4, 2020 #9

    I agree it would be better to give notice it's not typical for average users and give a link to a description of why one may want to change this to /24 if it was a mistake in configuration and a way to accept it is by design which dismisses further warnings.

    InfoSec911
  • InfoSec911
    InfoSec911 Member Posts: 17
    10 Comments Photogenic
    I like the suggestion for dismissing future warnings.  These messages are a real pain in the butt.
  • rooted
    rooted Gulf Coast, USModerator Posts: 892
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    I have to imagine it's just something that hasn't been addressed yet.
  • Robin_from_Fing
    Robin_from_Fing Administrator, Fing Team Posts: 5,052
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    Thanks for the feedback everyone. We are compiling the suggestions for warning dismissal and I have included the suggestion for developers to review.
    Robin (Admin at Fing)
    Getting Started? Please refer to Community guidelines & Community User Guides. HAPPY POSTING!!!
    rooted
  • Waldhaus2
    Waldhaus2 Member Posts: 5
    First Anniversary First Comment Photogenic
    I still need help with this. Tried posting a week ago but can't find if my post was noted or answered. If it will make Fing happier I will edit the subnet mask in my router - but I don't know what each set of digits stand for. Is there a dropbox reference or other reference that will tell me what different subnet mask to use. My mask is: 192.164.4.0/22 and apparently allows up to 1024 devices.
    I am more or less a network novice. I presume making one of those numbers smaller would be more appropriate for a home network and I guess those numbers represent exponents for 2. I could use an example or a reference.
  • Robin_from_Fing
    Robin_from_Fing Administrator, Fing Team Posts: 5,052
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    Hi @Waldhaus2
    Using the correct network size helps the Fing App or other devices on the network to perform efficiently. For Fing app, it will help to do regular scans of network. If the larger network size is set then it means it needs to scan more IP addresses until next scan. Here is a sample video explaining the network size

    Link: https://www.youtube.com/watch?v=MmA0-978fSk
    Robin (Admin at Fing)
    Getting Started? Please refer to Community guidelines & Community User Guides. HAPPY POSTING!!!
  • Waldhaus2
    Waldhaus2 Member Posts: 5
    First Anniversary First Comment Photogenic
    The video is very helpful. Now I see how to edit network size - i.e. make the number after the slash a bit bigger.
    When I check my router, an Eero it shows the gateway router's I.P address. Now I need to find out how to edit the network mask. I have asked Eero about that. I do have a 5 port ethernet router plugged into the Eero. I don't know if that triggers a larger network mask space.
    Ciaran
  • InfoSec911
    InfoSec911 Member Posts: 17
    10 Comments Photogenic
    Robin, the "correct" network size is based on what the network is doing, not the tools monitoring it.  I know your answer is for a different issue than mine, but stating that your customer's networks are not correct, is incorrect.  I have two hardware devices and now the app and have loved them up until you told me (with many messages every time I change a network or turn on my machine) that my "network is not tuned correctly".  I know what you are suggesting, but your verbiage is incorrect.  I would ask that you provide a more accurate message and a way for me to disable that message, as your product does not know what correct is for my network.
  • Ciaran
    Ciaran Administrator Posts: 1,180
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    Thanks @InfoSec911, completely valid point regarding explanation. Regarding disabling the message/notification, unfortunately, currently this is not posisble. However, after receiving other feedback in relation to the requirement to dismiss notifications/warnings (for various reasons), we have escalated this to our Dev team to review (see another thread relating to this: https://community.fing.com/discussion/3072/fiing-desktop-idea-dismiss-a-warning-option/p1?new=1). Thanks again for you feedback and suggestions. Ciaran
    Ciaran (Admin at Fing)

  • AFSSBill
    AFSSBill Member Posts: 1
    First Comment Photogenic
    I can second all this. I have four subnets at home, so correctly have a /22 class B/C network. Essentially this is because I have some priority devices connected directly to my gateway router, and then I have additional subnets for my home network via Eero, a network created by my television boxes (Sky TV), and a third subnet for work stuff. Therefore I CORRECTLY have an aaa.bbb.252.xxx or /22 network. 
    Ciaran
  • Ciaran
    Ciaran Administrator Posts: 1,180
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    admin
    Hi folks, good news. We heard you, took your feedback and now our Development team have confirmed the work on the ability to disbale alerts/messages is almost complete, and it is due to be included on the next release of the Fing Desktop . Thanks again for all of your feedback smile
    Ciaran (Admin at Fing)

    rooted
  • InfoSec911
    InfoSec911 Member Posts: 17
    10 Comments Photogenic
    Appreciate the update on the ability to disable the alerts.  I hope you are also working on the alert itself and making it correct and accurate.
    Thank You!!
  • InfoSec911
    InfoSec911 Member Posts: 17
    10 Comments Photogenic
    Thank you, Thank you, Thank you.  An initial look at the new version resolves this problem, no more inaccurate warnings about my subnet.
  • InfoSec911
    InfoSec911 Member Posts: 17
    10 Comments Photogenic
    Just downloaded the new 1.2.0.  Still incorrectly labels /23 network.  Still says it is not tuned correctly and is too wide.
    That is incorrect as stated in earlier posts on this thread.
  • Robin_from_Fing
    Robin_from_Fing Administrator, Fing Team Posts: 5,052
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    Just downloaded the new 1.2.0.  Still incorrectly labels /23 network.  Still says it is not tuned correctly and is too wide.
    That is incorrect as stated in earlier posts on this thread.
    Thanks for the feedback. Can you please make sure the network context is set correctly and Can you try to disable the alert for time being. I will share your feedback with our developers. Thanks again
    Robin (Admin at Fing)
    Getting Started? Please refer to Community guidelines & Community User Guides. HAPPY POSTING!!!
  • InfoSec911
    InfoSec911 Member Posts: 17
    10 Comments Photogenic
    How do I disable the alerts?
  • Robin_from_Fing
    Robin_from_Fing Administrator, Fing Team Posts: 5,052
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    admin
    How do I disable the alerts?
    On our latest version, Next to the warning there is a question mark (?) icon, if you click on it then you will be able to MUTE the warning. Can you please click on the icon and then check if it resolves the issue or not?
    Robin (Admin at Fing)
    Getting Started? Please refer to Community guidelines & Community User Guides. HAPPY POSTING!!!
  • InfoSec911
    InfoSec911 Member Posts: 17
    10 Comments Photogenic
    Thanks!  I was able to mute the warning.  This resolves the annoyance of the alarm, but does not resolve the incorrect error message.  Thanks!
  • InfoSec911
    InfoSec911 Member Posts: 17
    10 Comments Photogenic
    Just upgraded to 1.3.  Still incorrectly notifies on /23 networks.
  • InfoSec911
    InfoSec911 Member Posts: 17
    10 Comments Photogenic
    I just upgraded to 1.4.  Still incorrectly documents a /23 subnet mask as "not tuned correctly".  I have it muted, but that message is just incorrect.