+
+
+-u option
+~~~~~~~~~
+
+The '-u' option passes through connections for hostnames with no stored
+certificate (i.e. `certificate-*-server.pem` is missing or unreadable). In
+this case the normal CA chain in your browser lets you validate the server
+certificate. If the server certificate changes you're _not_ informed!
+
+This option is useful if you often visit websites using HTTPS but you don't
+use critical information (e.g. no passwords, etc.) on these websites.
+
+For hostnames with a stored server certificate everything works as usual and a
+certificate change is detected.
+
+WARNING: The option might cause security problems if you're not careful:
+
+For example you normally visit https://example.org/ and store the server
+certificate in `certificate-example.org.server.pem`. Without '-u' everything
+is fine.
+
+But if you use '-u' and an attacker redirects you to e.g.
+https://www.example.org/ - leading .www - (or https://whatever.org/) (for
+example through a link on a different site) then the proxy just forwards the
+TLS connection (because it doesn't know the fingerprint for
+https://www.example.org/, that's how '-u' works) and you won't be aware that a
+different server certificate might be used!
+
+If you always verify the authentication of the connection this isn't a
+problem, but if you only check if it's a HTTPS connection then this attack is
+possible.
+
+
+KNOWN ISSUES
+------------
+
+- Firefox (at least Iceweasel 3.5.16 on Debian) fails to load the error page
+ sent with the "invalid" certificate once the certificate has been accepted.
+ As the user shouldn't accept the invalid certificate this is a minor issue.
+
+
+AUTHORS
+-------
+
+Written by Simon Ruderich <simon@ruderich.org>.
+
+
+LICENSE
+-------
+
+tlsproxy is licensed under GPL version 3 or later.
+
+Copyright (C) 2011-2013 Simon Ruderich
+
+This program is free software: you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation, either version 3 of the License, or
+(at your option) any later version.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with this program. If not, see <http://www.gnu.org/licenses/>.