No:The-Me

Apache2 reverse proxy with SSL

Following up on the last post, here I am outlining how to make reverse
proxy work with SSL,

$ sudo a2enmod ssl*

to enable all Apache SSL modules.
After this I appended the following code in the file
/etc/apache2/sites-available/default-ssl

 
 AddDefaultCharset off 
 Order deny,allow 
 Allow from all 
 
SSLProxyEngine on 
SSLProxyCACertificateFile /etc/apache2/cacerts.crt 
ProxyPass /abc https://xxx.xxx.xx.xx:4400/abc 
ProxyPassReverse /abc https://xxx.xxx.xx.xx:4400/abc 
ProxyVia off

Since I was re-directing to a secure server, I faced two errors:

[error] [client xxx.xxx.xx.xx] SSL Proxy requested for 
127.0.1.1:443 but not enabled [Hint: SSLProxyEngine] 
[error] proxy: HTTPS: failed to enable ssl support for 
xxx.xxx.xx.xx:4400 (xxx.xxx.xx.xx)

The main reasons being, first I had forgotten to add the
SSLProxyEngine parameter to the configuration.
Secondly, when apache acts as a proxy, it acts like a client
requesting over SSL. Hence it needs the server certificate (PEM
encoded) to do a successful handshake.
Using openSSL,

openssl s_client -connect xxx.xxx.xx.xx:4400 -showcerts

Copied the encoded content from -----BEGIN CERTIFICATE----- & -----END
CERTIFICATE----- , saved it to cacerts.crt.
After this apache started serving SSL access to remote server via proxy.