mirror of
https://github.com/vanitasvitae/Smack.git
synced 2024-11-15 08:42:05 +01:00
76 lines
2.7 KiB
Markdown
76 lines
2.7 KiB
Markdown
|
DNSSEC and DANE
|
||
|
|
===============
|
||
|
|
|
||
|
|
[Back](index.md)
|
||
|
|
|
||
|
|
**DNSSEC and DANE support in Smack and MiniDNS is still in its
|
||
|
|
infancy. It should be considered experimental and not ready for
|
||
|
|
production use at this time.** We would like to see more thorough
|
||
|
|
testing and review by the security community. If you can help, then
|
||
|
|
please do not hesitate to contact us.
|
||
|
|
|
||
|
|
About
|
||
|
|
-----
|
||
|
|
|
||
|
|
DNSSEC ([RFC 4033](https://tools.ietf.org/html/rfc4033) and others)
|
||
|
|
authenticates DNS answers, positive and negative ones. This means that
|
||
|
|
if a DNS response secured by DNSSEC turns out to be authentic, then
|
||
|
|
you can be sure that the domain either exists, and that the returned
|
||
|
|
resource records (RRs) are the ones the domain owner authorized, or
|
||
|
|
that the domain does not exists and that nobody tried to fake its non
|
||
|
|
existence.
|
||
|
|
|
||
|
|
The tricky part is that an application using DNSSEC can not determine
|
||
|
|
whether a domain uses DNSSEC, does not use DNSSEC or if someone
|
||
|
|
downgraded your DNS query using DNSSEC to a response without DNSSEC.
|
||
|
|
|
||
|
|
[DANE](https://tools.ietf.org/html/rfc6698) allows the verification of
|
||
|
|
a TLS certificate with information stored in the DNS system and
|
||
|
|
secured by DNSSEC. Thus DANE requires DNSSEC.
|
||
|
|
|
||
|
|
Prerequisites
|
||
|
|
-------------
|
||
|
|
|
||
|
|
From the three DNS resolver providers (MiniDNS, javax, dnsjava)
|
||
|
|
supported by Smack only [MiniDNS](https://github.com/rtreffer/minidns)
|
||
|
|
currently supports DNSSEC. MiniDNS is the default resolver when
|
||
|
|
smack-android is used. For other configurations, make sure to add
|
||
|
|
smack-resolver-minidns to your dependencies and call
|
||
|
|
`MiniDnsResolver.setup()` prior using Smack (e.g. in a `static {}`
|
||
|
|
code block).
|
||
|
|
|
||
|
|
DNSSEC API
|
||
|
|
----------
|
||
|
|
|
||
|
|
Smack's DNSSEC API is very simple: Just use
|
||
|
|
`ConnectionConfiguration.Builder..setDnssecMode(DnssecMode)` to enable
|
||
|
|
DNSSEC. `DnssecMode` can be one of
|
||
|
|
|
||
|
|
- `disabled`
|
||
|
|
- `needsDnssec`
|
||
|
|
- `needsDnssecAndDane`
|
||
|
|
|
||
|
|
The default is `disabled`.
|
||
|
|
|
||
|
|
If `needsDnssec` is used, then Smack will only connect if the DNS
|
||
|
|
results required to determine a host for the XMPP domain could be
|
||
|
|
verified using DNSSEC.
|
||
|
|
|
||
|
|
If `needsDnssecAndDane` then DANE will be used to verify the XMPP
|
||
|
|
service's TLS certificate if STARTTLS is used. Note that you may want
|
||
|
|
to configure
|
||
|
|
`ConnectionConfiguration.Builder.setSecurityMode(SecurityMode.required)`
|
||
|
|
if you use this DNSSEC mode setting.
|
||
|
|
|
||
|
|
Best practices
|
||
|
|
--------------
|
||
|
|
|
||
|
|
We recommend that applications using Smack's DNSSEC API do not ask the
|
||
|
|
user if DNSSEC is avaialble. Instead they should check for DNSSEC
|
||
|
|
suport on every connection attempt. Once DNSSEC support has been
|
||
|
|
discovered, the application should use the `needsDnssec` mode for all
|
||
|
|
future connection attempts. The same scheme can be applied when using
|
||
|
|
DANE. This approach is similar to the scheme established by
|
||
|
|
to
|
||
|
|
["HTTP Strict Transport Security" (HSTS, RFC 6797)](https://tools.ietf.org/html/rfc6797).
|