doc: Fix hyperlinks in openvpn(8)

* http://www.cs.ucsd.edu/users/mihir/papers/hmac.html - 404, RFC104 basically
* http://sites.inka.de/sites/bigred/devel/tcp-tcp.html - 404, unfortunately
* http://www.ietf.org/rfc/rfc2246.txt - HTTPS upgrade to the HTML version

Signed-off-by: Christian Kujau <[email protected]>

Author: ckujau

doc/man-sections/link-options.rst

@@ -338,7 +338,7 @@ the local and the remote host.
   used over unreliable or congested networks.
 
   This article outlines some of problems with tunneling IP over TCP:
-  http://sites.inka.de/sites/bigred/devel/tcp-tcp.html
+  https://web.archive.org/web/20141025181658/http://sites.inka.de/sites/bigred/devel/tcp-tcp.html
 
   There are certain cases, however, where using TCP may be advantageous
   from a security and robustness perspective, such as tunneling non-IP or

doc/man-sections/protocol-options.rst

@@ -52,7 +52,7 @@ configured in a compatible way between both the local and remote side.
   authentication.
 
   For more information on HMAC see
-  http://www.cs.ucsd.edu/users/mihir/papers/hmac.html
+  https://tools.ietf.org/html/rfc2104
 
 --cipher alg
   This option should not be used any longer in TLS mode and still

doc/openvpn.8.rst

@@ -150,10 +150,10 @@ NOTES
 This product includes software developed by the OpenSSL Project
 (https://www.openssl.org/)
 
-For more information on the TLS protocol, see
-http://www.ietf.org/rfc/rfc2246.txt
+For more information on the TLS protocol see:
+https://tools.ietf.org/html/rfc2246
 
-For more information on the LZO real-time compression library see
+For more information on the LZO real-time compression library see:
 https://www.oberhumer.com/opensource/lzo/