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Home Forums Block website with NBAR on Cisco Router

This topic contains 7 replies, has 1 voice, and was last updated by   Rene Molenaar 1 year, 11 months ago.

Viewing 7 posts - 1 through 7 (of 7 total)
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  • #13820


    you can block http site with that, but you cannot block HTTPs sites with these


    Rene Molenaar

    Hi Sameer,

    I just updated the article to show you why we can’t block HTTPS with NBAR.




    This is awesome! Thanks



    What is the limit? I tried adding a lot of websites and it only shows me 7 of them when i do a show run.


    Rene Molenaar

    Hi Sandra,

    I’m not sure but there might be a limit on the number of URLs. If you have many websites to block like facebook or youtube you might want to lookup their IP address ranges and block those instead.




    Unfortunately, can’t block https (youtube, mail.ru, etc)
    Instead create access-list and deny all ip for approxx 30 addresses for youtube.
    Is another way to block youtube for example?


    Rene Molenaar

    Hi Vitaly,

    HTTPS won’t work since NBAR can’t look into the packets. I don’t think Youtube publishes a list of all IP addresses that they use, maybe you can lookup their AS number, find the IP addresses and block those:


    If you enter “Youtube” you can see that they use AS36561 and AS43515. You can lookup those IP addresses and block those.

    Perhaps a better method would be to fix this using DNS. Use your DNS server so resolves youtube.com to a custom webpage and configure your firewall so users can’t use another DNS server.


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