# OBSOLETE
With the [removal of TLS-SNI validation](https://community.letsencrypt.org/t/2018-01-11-update-regarding-acme-tls-sni-and-shared-hosting-infrastructure/50188),
this plugin is obsolete. If you just need basic renewal hook support, you can
use the [built-in hook options](https://certbot.eff.org/docs/using.html#pre-and-post-validation-hooks)
present in recent versions of certbot. If you need more features, consider
[EnigmaBridge/certbot-external-auth](https://github.com/EnigmaBridge/certbot-external-auth)
in handler mode, which is inspired by this plug-in but also supports HTTP-01
and DNS-01 validation.
## External shell script plugin for Let's Encrypt client
This plugin allows you to use a custom shell script to implement DVSNI
validation for your domains. It should work with any conceivable server that
supports TLS and SNI, and can also be used to perform DVSNI validation using
a server (e.g. a web server) that is unrelated to the server that will be using
the certificate (e.g. a mail server), as long as both share the same external
IP address.
The [example external-handler.sh](external-handler.sh.example) supports DVSNI
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