6-Day and IP Address Certificates Are Generally Available

(letsencrypt.org)

122 points | by jaas 2 hours ago

8 comments

  • ivanr 1 hour ago
    As already noted on this thread, you can't use certbot today to get an IP address certificate. You can use lego [1], but figuring out the exact command line took me some effort yesterday. Here's what worked for me:

        lego --domains 206.189.27.68 --accept-tos --http --disable-cn run --profile shortlived
    
    [1] https://go-acme.github.io/lego/
    • Svoka 1 hour ago
      I wonder if the support made it to Caddy yet

      (seems to be WIP https://github.com/caddyserver/caddy/issues/7399)

      • mholt 23 minutes ago
        It works, but as another comment mentioned there may be quirks with IP certs, specifically IPv6, that I hope will be fixed by v2.11.
      • jsheard 56 minutes ago
        IPv4 certs are already working fine for me in Caddy, but I think there's some kinks to work out with IPv6.
  • qwertox 11 minutes ago
    I have now implemented a 2 week renewal interval to test the change to the 45 days, and now they come with a 6-day certificate?

    This is no criticism, I like what they do, but how am I supposed to do renewals? If something goes wrong, like the pipeline triggering certbot goes wrong, I won't have time to fix this. So I'd be at a two day renewal with a 4 day "debugging" window.

    I'm certain there are some who need this, but it's not me. Also the rationale is a bit odd:

    > IP address certificates must be short-lived certificates, a decision we made because IP addresses are more transient than domain names, so validating more frequently is important.

    Are IP addresses more transient than a domain within a 45 day window? The static IPs you get when you rent a vps, they're not transient.

    • bigstrat2003 8 minutes ago
      The push for shorter and shorter cert lifetimes is a really poor idea, and indicates that the people working on these initiatives have no idea how things are done in the wider world.
  • gruez 1 hour ago
    For people who want IP certificates, keep in mind that certbot doesn't support it yet, with a PR still open to implement it: https://github.com/certbot/certbot/pull/10495

    I think acme.sh supports it though.

    • mcpherrinm 1 hour ago
      Some ACME clients that I think currently support IP addresses are acme.sh, lego, traefik, acmez, caddy, and cert-manager. Certbot support should hopefully land pretty soon.
      • sgtcodfish 17 minutes ago
        cert-manager maintainter chiming in to say that yes, cert-manager should support IP address certs - if anyone finds any bugs, we'd love to hear from you!

        We also support ACME profiles (required for short lived certs) as of v1.18 which is our oldest currently supported[1] version.

        We've got some basic docs[2] available. Profiles are set on a per-issuer basis, so it's easy to have two separate ACME issuers, one issuing longer lived certs and one issuing shorter, allowing for a gradual migration to shorter certs.

        [1]: https://cert-manager.io/docs/releases/ [2]: https://cert-manager.io/docs/configuration/acme/#acme-certif...

  • bflesch 19 minutes ago
    This sounds like a very good thing, like a lot of stuff coming from letsencrypt.

    But what risks are attached with such a short refresh?

    Is there someone at the top of the certificate chain who can refuse to give out further certificates within the blink of an eye?

    If yes, would this mean that within 6 days all affected certificates would expire, like a very big Denial of Service attack?

    And after 6 days everybody goes back to using HTTP?

    Maybe someone with more knowledge about certificate chains can explain it to me.

    • iso1631 12 minutes ago
      With a 6 day lifetime you'd typically renew after 3 days. If Lets Encrypt is down or refuses to issue then you'd have to choose a different provider. Your browser trusts many different "top of the chain" providers.

      With a 30 day cert with renewal 10-15 days in advance that gives you breathing room

      Personally I think 3 days is far too short unless you have your automation pulling from two different suppliers.

  • iamrobertismo 1 hour ago
    This is interesting, I am guessing the use case for ip address certs is so your ephemeral services can do TLS communication, but now you don't need to depend on provisioning a record on the name server as well for something that you might be start hundreds or thousands of, that will only last for like an hour or day.
    • medmunds 5 minutes ago
      The July announcement for IP address certs listed a handful of potential use cases: https://letsencrypt.org/2025/07/01/issuing-our-first-ip-addr...
    • jeroenhd 13 minutes ago
      One thing this can be useful for is encrypted client hello (ECH), the way TLS/HTTPS can be used without disclosing the server name to any listening devices (standard SNI names are transmitted in plaintext).

      To use it, you need a valid certificate for the connection to the server which has a hostname that does get broadcast in readable form. For companies like Cloudflare, Azure, and Google, this isn't really an issue, because they can just use the name of their proxies.

      For smaller sites, often not hosting more than one or two domains, there is hardly a non-distinct hostname available.

      With IP certificates, the outer TLS connection can just use the IP address in its readable SNI field and encrypt the actual hostname for the real connection. You no longer need to be a third party proxying other people's content for ECH to have a useful effect.

    • traceroute66 38 minutes ago
      > I am guessing the use case for ip address certs is so your ephemeral services can do TLS communication

      There's also this little thing called DNS over TLS and DNS over HTTPS that you might have heard of ? ;)

    • axus 1 hour ago
      No dependency on a registrar sounds nice. More anonymous.
      • traceroute66 30 minutes ago
        > No dependency on a registrar sounds nice.

        Actually the main benefit is no dependency on DNS (booth direct and root).

        IP is a simple primitive, i.e. "is it routable or not ?".

      • organsnyder 1 hour ago
        IP addresses also are assigned by registrars (ARIN in the US and Canada, for instance).
        • traceroute66 33 minutes ago
          > IP addresses also are assigned by registrars (ARIN in the US and Canada, for instance).

          To be pedantic for a moment, ARIN etc. are registries.

          The registrar is your ISP, cloud provider etc.

          You can get a PI (Provider Independent) allocation for yourself, usually with the assistance of a sponsoring registrar. Which is a nice compromise way of cutting out the middleman without becoming a registrar yourself.

          • immibis 25 minutes ago
            You can also become a registrar yourself - at least, RIPE allows it. However, fees are significantly higher and it's not clear why you'd want to, unless you were actually providing ISP services to customers (in which case it's mandatory - you're not allowed to use a PI allocation for that)
            • traceroute66 12 minutes ago
              > and it's not clear why you'd want to

              The biggest modern-era reason is direct access to update your RPKI entries.

              But this only matters if you are doing stuff that makes direct access worthwhile.

              If your setup is mostly "set and forget" then you should just accept the lag associated with needing to open a ticket with your sponsor to update the RPKI.

        • buckle8017 47 minutes ago
          Arguably neither is particularly secure, but you must have an IP so only needing to trust one of them seems better.
    • iamrobertismo 1 hour ago
      Yeah actually seems pretty useful to not rely on the name server for something that isn't human facing.
    • pdntspa 44 minutes ago
      Maybe you want TLS but getting a proper subdomain for your project requires talking to a bunch of people who move slowly?
      • iamrobertismo 40 minutes ago
        Very very true, never thought about orgs like that. However, I don't think someone should use this like a bandaid like that. If the idea is that you want to have a domain associated with a service, then organizationally you probably need to have systems in place to make that easier.
        • pdntspa 13 minutes ago
          Ideally, sure. But in some places you're what you're proposing is like trying to boil the oceans to make a cup of tea

          VBA et al succeeded because they enabled workers to move forward on things they would otherwise be blocked on organizationally

          Also - not seeing this kind of thing could be considered a gap in your vision. When outsiders accuse SV of living in a high-tech ivory tower, blind to the realities of more common folk, this is the kind of thing they refer to.

  • meling 50 minutes ago
    If I can use my DHCP assigned IP, will this allow me to drop having to use self-signed certificates for localhost development?
    • wolttam 30 minutes ago
      Browsers consider ‘localhost’ a secure context without needing https

      For local /network/ development, maybe, but you’d probably be doing awkward hairpin natting at your router.

      • treve 26 minutes ago
        it's nice to be able to use https locally if you're doing things with HTTP/2 specifically.
    • michaelt 43 minutes ago
      No, they will only give out certificates if you can prove ownership of the IP, which means it being publicly routable.
      • wongarsu 21 minutes ago
        Finally a reason to adopt IPv6 for your local development
      • inetknght 33 minutes ago
        A lot of publicly routable IP addresses are assigned by DHCP...
  • zamadatix 1 hour ago
    Does anyone know when Caddy plans on supporting this?
  • hojofpodge 41 minutes ago
    Something about a 6 day long IP address based token brings me back to the question of why we are wasting so much time on utterly wrong TOFU authorization?

    If you are supposed to have an establishable identity I think there is DNSSEC back to the registrar for a name and (I'm not quite sure what?) back to the AS.for the IP.

    • ycombinatrix 37 minutes ago
      Domains map one-to-one with registrars, but multiple AS can be using the same IP address.
      • hojofpodge 29 minutes ago
        Then it would be a grave error to issue an IP cert without active insight into BGP. (Or it doesn't matter which chain you have.. But calling a website from a sampling of locations can't be a more correct answer.)