troubleshooting_https.diviner

@title Troubleshooting HTTPS
@group config

Detailed instructions for troubleshooting HTTPS connection problems.

= Overview =

If you're having trouble connecting to an HTTPS install of Phabricator, and
particularly if you're receiving a "There was an error negotiating the SSL
connection." error, this document may be able to help you diagnose and resolve
the problem.

Connection negotiation can fail for several reasons. The major ones are:

  - You have not added the Certificate Authority as a trusted authority
    (this is the most common problem, and usually the issue for self-signed
    certificates).
  - The SSL certificate is signed for the wrong domain. For example, a
    certificate signed for `www.example.com` will not work for
    `phabricator.example.com`.
  - The server rejects TLSv1 SNI connections for the domain (this is
    complicated, see below).

= Certificate Authority Problems =

SSL certificates need to be signed by a trusted authority (called a Certificate
Authority or "CA") to be accepted. If the CA for a certificate is untrusted, the
connection will fail (this defends the connection from an eavesdropping attack
called "man in the middle"). Normally, you purchase a certificate from a known
authority and clients have a list of trusted authorities.

You can self-sign a certificate by creating your own CA, but clients will not
trust it by default. They need to add the CA as a trusted authority.

For instructions on adding CAs, see `libphutil/resources/ssl/README`.

If you'd prefer that `arc` not verify the identity of the server whatsoever, you
can use the `https.blindly-trust-domains` setting. This will make it
dramatically easier for adversaries to perform certain types of attacks, and is
**strongly discouraged**:

  $ arc set-config https.blindly-trust-domains '["example.com"]'


= Domain Problems =

Verify the domain the certificate was issued for. You can generally do this
with:

  $ openssl x509 -text -in <certificate>

If the certificate was accidentally generated for, e.g. `www.example.com` but
you installed Phabricator on `phabricator.example.com`, you need to generate a
new certificate for the right domain.

= SNI Problems =

Server Name Identification ("SNI") is a feature of TLSv1 which works a bit like
Apache VirtualHosts, and allows a server to present different certificates to
clients who are connecting to it using different names.

Servers that are not configured properly may reject TSLv1 SNI requests because
they do not recognize the name the client is connecting with. This
topic is complicated, but you can test for it by running:

  $ openssl s_client -connect example.com:443 -servername example.com

Replace **both** instances of "example.com" with your domain. If you receive
an error in `SSL23_GET_SERVER_HELLO` with `reason(1112)`, like this:

  CONNECTED(00000003)
  87871:error:14077458:SSL routines:SSL23_GET_SERVER_HELLO:reason(1112):
    /SourceCache/OpenSSL098/OpenSSL098-44/src/ssl/s23_clnt.c:602:

...it indicates server is misconfigured. The most common cause of this problem
is an Apache server that does not explicitly name the Phabricator domain as a
valid VirtualHost.

This error occurs only for some versions of the OpenSSL client library
(from v0.9.8r or earlier until 1.0.0), so only some users may experience it.