Hi, I'm currently estimating how "vulnerable" certain IP addresses are to BGP hijacking. To do that, I put them into different categories (multiple can apply): a) RPKI validity state is "NotFound" (no ROA) and IP located in a prefix shorter than /24 (IPv4) or /48 (IPv6) b) Valid ROA but weak maxlength c) Valid ROA with proper maxlength d) is announced in a /24 prefix (IPv4) or /48 (IPv6) e) = (c) + (d) In addition to the distinction of prefix length (/24 vs. </24) I'd like to subcategorize /24 prefixes into - /24 prefix located in "well" connected AS (attacker's BGP visibility is presumed lower than the authentic AS visibility) - /24 prefix located in "poorly" connected AS (better for the attacker) The question is: What is the threshold and metric to tell these two apart? I'm having 3 approaches in mind and wanted to hear if you have any preferences, opinions or other approaches: Approach 1: ----------- If avg AS PATH length as provided by [1] is <2 in more than 50% of given locations and DE-CIX and AMS-IX is among them, then consider it a "well connected AS" Approach 2: ----------- Use CAIDA's AS rank data and define the top 50% ASes as "well" connected Approach 3: ----------- define "well connected" as avg AS PATH as seen in [1] is shorter than the global avg. AS PATH length (defined in [2]) Also: If there are already well established metrics for "well connected" AS I'd be happy to hear about them. Currently I'm leaning towards approach 1 as it is probably the strictest and most conservative approach. I also might compare the results of all 3 approaches. thanks! nusenu [1] https://stat.ripe.net/docs/data_api#AsPathLength [2] http://thyme.rand.apnic.net/current/data-summary (the mean value would actually be more interesting than the avg) Because it is hard to collect ROV data and the list on https://rov.rpki.net is still short I do not try to include a ROV metric (yet).