4 ms·

Cert-manager has great support for a number of providers[0] including AWS, CloudFlare, Google Cloud, and Azure. I recommend this not just for internal IP setup

• tialaramex 6y ago
  I like DNS challenges, but I don't see how it matters for deprecation of an ACME challenge type. The dns-01 challenge could just as easily for some reason need to be deprecated. The two likely reasons for such deprecation would apply just as well: 1. Updated Baseline Requirements or a programme policy requirement at any of the major root trust stores could forbid this challenge or require it to be substantially modified, obsoleting it in its current form. 2. The BRs don't change but Let's Encrypt finds they need to adjust this particular implementation in a non-compatible way so they deprecate the current challenge. It can be easier to do DNS challenges, but it can also be very rough, depending on all the moving parts in your system.
  • sleevi 6y ago
    Both of those are reasonable concerns, if all other factors were ignored. However, in practice, the DNS challenge (which demonstrates control over DNS) is greatly preferred over HTTP/TLS challenges (which demonstrate control over a single port). DNS is likely to be the only way to get a wildcard certificate, and HTTP/TLS will likely end up further restricted once SRVNames in certificates can be gracefully rolled out. As such, deploying the DNS based control is absolutely the best thing to do, and HTTP/TLS should be seen as legacy-compat fallbacks that may become more difficult in time. Either certificates become less scoped than “entire domain” (as they are today with dNSName SANs) or it becomes more difficult to use a single port to prove authorization for an entire domain.
    • sroussey 6y ago
      But can’t DNS queries be altered man in the middle style?
      • sleevi 6y ago
        I’m not sure your point? Any HTTP/ALPN request first begins with DNS, so if you’re trying to compare those, they all share the same base issue. In theory, this can be mitigated by DNSSEC, but that’s not relevant when comparing these validation methods. However, both the HTTP and ALPN methods only demonstrate control over a single port (or .well-known resource), while the DNS method demonstrates the full ability to alter any/all names.
        • sroussey 6y ago
          Actually, I suppose DNS with DNSSEC or DNS over HTTPS would be better than any HTTP method.
• z3t4 6y ago
  Verification via DNS is not without issues. If you have more then one DNS server the verification record need to propagate to all servers. If you for example use anycast DNS you will run into issues. Letsencrypt uses Google name servers for lookup which is problematic because they do not behave, they will for example not try secondary dns servers if the first try fail, making the Letsencrypt verification also fail. And because of these issues and if you have many domains you will quickly reach Letsencrypt quota.
  • sleevi 6y ago
    Where have you seen Let’s Encrypt using Google’s servers? CAs are required to run full recursive resolvers, up to the root, and can’t just point at someone else’s DNS infrastructure. Which, if you think about it, is what you want: you don’t want the CA just trusting someone else is being honest, you want to go to the authoritative source.
  • radiowave 6y ago
    In which case it may be advisable to delegate the acme-challenge record to a different DNS provider, if doing so allows you to sidestep the anycast issues.
  • mercora 6y ago
    i had this issue but i just set the time to wait for propagation high enough to be somewhat certain and had no further issues since (its 10m i think). it does not really matter to me how long it takes as its an automated process... should be finished before expiration though ^^ having multiple nameservers is pretty standard and often mandatory requirement set by the NICs. Its just that my secondary is sometimes not fast enough to transfer the zone after a change notification which triggers this issue. Also, retrying after an authoritative nameserver said there is defacto no record seems pretty wrong to me... i doubt they use google DNS or anything really. in order to avoid caching issues they very likely resolve names recursively without (the usual) caching
  • throw0101a 6y ago
    > If you for example use anycast DNS you will run into issues. You're not wrong, but this assumes that you use the your 'service hostname' for verification as well, rather than using CNAMEs. So let us say you want to have "svc1.example.com" in your cert: you could put the ACME challenge under there, but if you have anycast delays that's a problem (as you mention). (A kludge is putting a 'sleep' somewhere to allow for propagation.) So instead what you can do is have "_acme-challenge.svc1.example.com" be a CNAME that points to (say) "_acme-challenge.svc1.dnsauth.example.com". This sub-domain is not anycast, and may actually be a single machine that is used solely for this purpose. The LE/ACME server goes to your main domain, finds a CNAME, and follows that to the real record and verification is achieved: * https://www.eff.org/deeplinks/2018/02/technical-deep-dive-securing-automation-acme-dns-challenge-validation https://www.eff.org/deeplinks/2018/02/technical-deep-dive-se... * https://dan.langille.org/2019/02/01/acme-domain-alias-mode/ https://dan.langille.org/2019/02/01/acme-domain-alias-mode/ * https://github.com/acmesh-official/acme.sh/wiki/DNS-alias-mode https://github.com/acmesh-official/acme.sh/wiki/DNS-alias-mo... The CNAME has to be set up initially, but can be left lying around otherwise. This is how $WORK deals with getting LE certs for internal domains: we create a CNAME record (but no A records) for the internal hostname in our external DNS that point to our "dnsauth" domain which gets updating by internal clients via an API.
• throw0101a 6y ago
  See also lexicon, which supports over 50 APIs: * https://github.com/AnalogJ/lexicon https://github.com/AnalogJ/lexicon