Auto detect a regular expression for your prefixes
BGPmon offers different ways to monitor your prefixes. One of the tools is using a Regex for your ASpaths. Basically what it does is, compare every BGP update for your prefix with the ASpaths regex you submitted. If the Regex doesn't match the ASpath in this particular update an alarm (code41) is generated. ASregex are a very powerfull method to monitor your prefixes. However it might be challenging to write a regex for your prefix. The FAQ and Help link in the My Prefixes page offer some help and examples. I think a good regex should have the originAS as well as upstream AS's. So something like: In this case AS271 can be seen behind 3 upstream (transit) AS's. If it would be seen behind for example AS6509 it would generate an alarm. If you have a lot of upstreams and/or peers, it might be quite a job to create a regex for this. Especially if you're peering at an Internet Exchange the number of peers might be quite high. To help you with this I added a new feature to BGPmon.net. This feature will try to detect all your upstreams/peers for your AS/prefix and will build a regex for you. This should reduce the false positive code41 (ASpath regex mismatch) alarms. You can use this functionality from the My Prefixes page by clicking on the button. It will list all the upstream AS's which are seen from the RIS servers I'm using and generate a Regex based on that data. You can than copy paste this regular expression in to the My Prefixes page. Also see the screenshot of the result on the right hand side. If you created an account you can test it yourself for your prefix, otherwise you can test it using the demo account as this functionality work for email@example.com as well. Hopefully you'll find this functionality usefull. If you have any feedback, please let me know.