Configuring proxies
Certain commands, for example, the dita install command, use a network connection to
    install plug-ins from the configured registry or process remote referenced resources. In environments where an HTTP
    proxy is used to establish a network connection, you can provide the proxy configuration via the
      ANT_OPTS environment variable. 
Procedure
- 
        To configure the proxy for a specific session, from the command prompt, issue the
          following command:
        Platform Command Linux or macOS export ANT_OPTS="-Dhttp.proxySet=true \ -Dhttps.proxyHost=<HTTPS proxy IP address> \ -Dhttp.proxyHost=<HTTP proxy IP address> \ -Dhttp.proxyPort=<HTTP proxy port> \ -Dhttps.proxyPort=<HTTPS proxy port>"Windows set ANT_OPTS=%ANT_OPTS% -Dhttp.proxySet=true ^ -Dhttps.proxyHost=<HTTPS proxy IP address> ^ -Dhttp.proxyHost=<HTTP proxy IP address> ^ -Dhttp.proxyPort=<HTTP proxy port> ^ -Dhttps.proxyPort=<HTTPS proxy port>
- 
        To persistently change the value, change the value allocated to the
            ANT_OPTSenvironment variable on your system.
What to do next
dita install <plug-in>