Comment 1 for bug 1777148

Something is weird:

$ HEAD http://ubuntu-archive.adsolux.com/ubuntu/dists/cosmic/main/binary-amd64/Packages.gz
200 OK
Connection: close
Date: Fri, 15 Jun 2018 14:30:18 GMT
Server: nginx
Vary: Accept-Encoding
Content-Type: text/html; charset=UTF-8
Client-Date: Fri, 15 Jun 2018 14:30:18 GMT
Client-Peer: 185.53.179.8:80
Client-Response-Num: 1
X-Adblock-Key: MFwwDQYJKoZIhvcNAQEBBQADSwAwSAJBALquDFETXRn0Hr05fUP7EJT77xYnPmRbpMy4vk8KYiHnkNpednjOANJcaXDXcKQJN0nXKZJL7TciJD8AoHXK158CAwEAAQ==_qPY4rlFewtdckgAsjtAuxnjrlauXNE9/sHWqo0dNlXqPhckUJMFH6zl97Ej9VVvKrv9mQv/WCCinH5j56sFrzg==
X-Buckets: bucket065
X-Check: 3c12dc4d54f8e22d666785b733b0052100c53444
X-Language: english
X-Template: tpl_CleanPeppermintBlack_twoclick

$ curl -iI http://ubuntu-archive.adsolux.com/ubuntu/dists/cosmic/main/binary-amd64/Packages.gz
HTTP/1.1 403 Forbidden
Server: nginx
Date: Fri, 15 Jun 2018 14:30:35 GMT
Content-Type: text/html
Content-Length: 162
Connection: keep-alive

I think it's doing User-Agent sniffing, and the prober uses something that causes it to return 200. Nasty.