Help using cisco DDNS for updating dynamic IP

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stoobie

Hello, I have configured my Cisco 871 router using the http update string for dnsomatic. In the router logs I see it sending the update request and getting a response that it was successful. the issue that I'm seeing is that when I look it up on dnsomatic web page it doesn't show those updates under "history".  

Here are my logs: ( I replaced my IP with XXX.XXX.XXX.XXX to not post my IP and removed username/password from string)

000632: Mar 11 11:50:13.699 GMT: HTTPDNSUPD: URL = 'http://EMAILADDRESS:PASSWORD@updates.dnsomatic.com/nic/update?hostname=all.dnsomatic.com&myip=XXX.XXX.XXX.XXX'
000633: Mar 11 11:50:13.699 GMT: HTTPDNSUPD: Sending request
000634: Mar 11 11:50:14.210 GMT: HTTPDNSUPD: Response for update all.dnsomatic.com <=> XXX.XXX.XXX.XXX

000635: Mar 11 11:50:14.210 GMT: HTTPDNSUPD: DATA START

000636: Mar 11 11:50:14.210 GMT: HTTPDNSUPD: DATA END, Status is Response data recieved, successfully
000637: Mar 11 11:50:14.210 GMT: HTTPDNSUPD: Call returned SUCCESS for update all.dnsomatic.com <=> XXX.XXX.XXX.XXX
000638: Mar 11 11:50:14.210 GMT: DYNDNSUPD: Another update completed (outstanding=0, total=0)
000639: Mar 11 11:50:14.214 GMT: HTTPDNSUPD: Clearing all session 55 info

Am I missing something?

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  • Avatar
    stoobie

    Router DDNS config

    ip ddns update method dnsomatic
    HTTP
    add http://[email@address]:[password]@updates.dnsomatic.com/nic/update?hostname=all.dnsomatic.com&myip=<a>
    remove http://[email@address]:[password]@updates.dnsomatic.com/nic/update?hostname=all.dnsomatic.com&myip=<a>
    interval maximum 1 0 0 0
    interval minimum 0 6 0 0

    interface FastEthernet4
    ip dhcp client update dns server both
    ip ddns update hostname all.dnsomatic.com
    ip ddns update dnsomatic
    ip address dhcp
    ip verify unicast source reachable-via rx allow-default 100
    no ip redirects
    no ip unreachables
    no ip proxy-arp
    ip nat outside
    ip virtual-reassembly
    speed auto
    full-duplex

     

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    rotblitz

    Enter the exact same update URL in a browser and see what is really returned.

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  • Avatar
    stoobie

    I  forgot to add that to original post, when I put that URL in a browser it returns "good xx.xx.xx.xx" and the update shows in my dnsomatic history as a successful update.

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    rotblitz

    Then the problem is with your Cisco 871, and you'll want to refer to Cisco support.  Most likely nobody can help you here, because the issue is not related to DNS-O-Matic, but to this update client.

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    matthew.john

    Stoobie, did you ever get this sorted. I have the exact same issue? 

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    Permanently deleted user

    Now in 2019 I have exactly the same issue.

    After much troubleshooting and comparing config with No-ip, I came to the conclusion that Dnsomatic is never going to work on a Cisco router because of the add string format.

    For Dnsomatic email in this string has to be example someone@somewhere.com

    add http://[email@address]:[password]@updates.dnsomatic.com/nic/update?hostname=all.dnsomatic.com&myip=<a>

     

    Comparing with a proven working No-ip config which use,

    add http://username:password@dynupdate.no-ip.com/nic/update?hostname=<h>&myip=<a>

     

    I think Cisco router is sensitive to the @ symbol appearing twice in the string, so it's never going to work with Dnsomatic.

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    rotblitz

    Try with replacing the @ character in the email address by %40

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    Permanently deleted user

    Very clever trick, i'm not a programmer i wouldn't think of using hex.

    Anyway it works ! I'm posting the final config here for the benefit of the community.

    This has been tested on IOS-XE 16.8.2

     

    ip ddns update method dnsomatic
    HTTP
    add http://someone%40somewhere.com:password@updates.dnsomatic.com/nic/update?hostname=all.dnsomatic.com&myip=<a>
    interval maximum 0 8 0 0
    interval minimum 0 0 5 0

    ip ddns update hostname your.no-ip.hostname
    ip ddns update dnsomatic

     

    In debug you will see these, the important part is "good x.x.x.x" this will indicate successful. If this line is missing then something is still wrong.

    HTTPDNSUPD: Sending request

    HTTPDNSUPD: Response for update your.no-ip.hostname <=> x.x.x.x

    HTTPDNSUPD: DATA START
    good x.x.x.x
    HTTPDNSUPD: DATA END, Status is Response data recieved, successfully

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    rotblitz

    Brilliant!

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    Permanently deleted user

    Since getting this to work back in 2019, it broke again sometime in June 2020. I didn't realise it until Dec 2021 when more categories start getting randomly blacklisted.

    After much troubleshooting, dnsomatic seems to have turned off HTTP without warning.

    Therefore this command will have to update.

    add https://username%40hotmail.com:password@updates.dnsomatic.com/nic/update?hostname=all.dnsomatic.com&myip=<a>

    Also Cisco routers doesn't have CA certs by default so the root CA cert for updates.dnsomatic.com will have to manually import.

    This badly formatted post shows the process, it works, just difficult to read.

    https://community.cisco.com/t5/other-security-subjects/ddns-update-over-https-ssl-cert-problem/td-p/1270094

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