Unable to detect missing reverse proxy configuration

Question

I have configured a reverse proxy server that will allow the client to communicate to an endpoint URL (https://uat-enq.ctos.com.my:8443/ctos/Proxy?wsdl) via it.

This is the reverse proxy config file :

<VirtualHost _default_:443>
    SSLEngine on
    # ServerName localhost
    SSLCertificateFile /etc/pki/tls/certs/localhost.crt
    SSLCertificateKeyFile /etc/pki/tls/private/localhost.key
    SSLProxyEngine On
    SSLProxyVerify require
    SSLProxyCheckPeerCN on
    SSLProxyCheckPeerExpire on
    ProxyRequests Off
    ProxyPreserveHost On
 
    ProxyPass /ctos/Proxy https://uat-enq.ctos.com.my:8443/ctos/Proxy acquire=100 retry=0 keepalive=on connectiontimeout=20
    ProxyPassReverse /ctos/Proxy https://uat-enq.ctos.com.my:8443/ctos/Proxy

    RewriteEngine On
    RewriteRule ^/ctos/Proxy(.*)$ /$1 [P]
</VirtualHost>

From this reverse proxy server, I am able to reach the endpoint URL with curl (photo attached).

However, when I run curl via the reverse proxy server, it fails (photo attached).

I am not sure how to debug the problem, as I have tried so many things, but it still fails. Some of the things I have done to debug :

• Check the httpd log files for the reverse proxy to see if there are any indications of why it fails

• Check connectivity between reverse proxy to endpoint URL via the 8443 port using telnet and curl : success

• Check connectivity between client to endpoint URL via the 8443 port using telnet and curl : telnet is a success, but curl returns SSL Connect (35) error. However this is related to curl version, which is why I am using the reverse proxy to substitute for the outdated TLS version of the client server to communicate with the endpoint URL.

• Check connectivity between client to reverse proxy via telnet port 443 : success

• X-Forwarded-For parameter : I did some googling and it mentioned something about allowing the client's ip using the X-Forwarded-For parameter in the reverse proxy server. However when I check httpd.conf, I see the parameter already there :

  # LogFormat
  
  LogFormat "%{X-Forwarded-For}i %h %l %u %t \"%r\" %>s %b [%Tsec] \"%{Referer}i\" \"%{User-Agent}i\"" combined
  LogFormat "%h %l %u %t \"%r\" %>s %b" common
  LogFormat "%{Referer}i -> %U" referer
  LogFormat "%{User-agent}i" agent
  

Could you please help pinpoint what are the errors/problems in my config to fix this issue? I still have no clue till this stage.

Curl from reverse proxy to endpoint URL

Curl from client to reverse proxy