TLS SNI alerts on LDAP vhosts

[presbrey]

void is a scripts-vhost:

presbrey@dr-wily:~$ host void.mit.edu
void.mit.edu is an alias for SCRIPTS-VHOSTS.mit.edu.
SCRIPTS-VHOSTS.mit.edu has address 18.181.0.46

that fails to handshake:

presbrey@dr-wily:~$ curl -k https://void.mit.edu/
curl: (35) error:14077458:SSL routines:SSL23_GET_SERVER_HELLO:reason(1112)

even though scripts-vhosts itself works:

presbrey@dr-wily:~$ curl -kv https://scripts-vhosts.mit.edu/
* About to connect() to scripts-vhosts.mit.edu port 443 (#0)
*   Trying 18.181.0.46... connected
* Connected to scripts-vhosts.mit.edu (18.181.0.46) port 443 (#0)
* successfully set certificate verify locations:
*   CAfile: none
  CApath: /etc/ssl/certs
* SSLv3, TLS handshake, Client hello (1):
* SSLv3, TLS handshake, Server hello (2):
* SSLv3, TLS handshake, CERT (11):
* SSLv3, TLS handshake, Server key exchange (12):
* SSLv3, TLS handshake, Server finished (14):
* SSLv3, TLS handshake, Client key exchange (16):
* SSLv3, TLS change cipher, Client hello (1):
* SSLv3, TLS handshake, Finished (20):
* SSLv3, TLS change cipher, Client hello (1):
* SSLv3, TLS handshake, Finished (20):
* SSL connection using DHE-RSA-AES256-SHA
* Server certificate:
*        subject: serialNumber=sKLt5io360jM-oAd2EGLNK0EraXwXE46; C=US; ST=Massachusetts; L=Cambridge; O=Massachusetts Institute of Technology; OU=scripts.mit.edu web hosting service; CN=scripts.mit.edu
*        start date: 2011-05-24 11:40:52 GMT
*        expire date: 2016-06-24 16:28:06 GMT
*        subjectAltName does not match scripts-vhosts.mit.edu
> GET / HTTP/1.1
> User-Agent: curl/7.21.0 (x86_64-pc-linux-gnu) libcurl/7.21.0 OpenSSL/0.9.8o zlib/1.2.3.4 libidn/1.15 libssh2/1.2.6
> Host: scripts-vhosts.mit.edu
> Accept: */*
>
< HTTP/1.1 200 OK
< Date: Thu, 28 Feb 2013 02:21:46 GMT

The problem has to do with TLS SNI extensions. TLS Alert 1112 is Level 1 (Warning) and Code 112 (Unrecognized name). This error is intended to notify the client that the server may not do what the client is expecting when the server does not recognize the SNI hostname passed by the client.

The server-side TLS SNI that validates "recognized" hostnames apparently only checks against hardcoded ServerName?(s) and ServerAlias?(s), and fails to locate LDAP vhosts as valid SNI targets.

[adehnert]

Is this the same thing as ​http://mokafive.tumblr.com/post/43065957659/openssl-1-0-sni-curl-interoperability-fail?

[geofft]

I think so, and also this is fixed in OpenSSL 1.0, which is pretty safe to assume at this point. (This bug was filed on Linerva, which was last running squeeze.)

[kaduk]

I'm not sure that openssl 1.0 can be assumed to be present everywhere. For example, FreeBSD 8.4 is still in support but ships with openssl 0.9.8zd or thereabouts