The `des3-hmac-sha1` and `rc4-hmac` Kerberos encryption types (etypes) are now deprecated and disabled by default. Users can set `allow_weak_crypto = true` in the `krb5.conf` configuration file to re-enable them (along with other weak etypes including `des-cbc-crc` and `des-cbc-md5`) at their own risk. To disable a subset of the weak etypes, users can list preferred etypes explicitly in any of the `default_tkt_enctypes`, `default_tgs_enctypes`, or `permitted_enctypes` settings.