Transfer or Restore a cPanel Account gets "connection refused" when trying to connect to port 2083 on remote server

Symptoms

When attempting to transfer accounts via WHM's "Transfer or Restore a cPanel Account" feature, the transfer fails with an error similar to:

TRANSFER: Account “cptest”: Error while executing “/usr/local/cpanel/scripts/getremotecpmove”. The “/usr/local/cpanel/scripts/getremotecpmove 10.2.34.41 cptest” command (process 302165) reported error number 255 when it ended.: Cpanel::Exception::HTTP::Network/(XID vqs9wf) The system failed to send an <abbr title="Hypertext Transfer Protocol">HTTP</abbr> “GET” request to “https://10.2.34.41:2083/json-api/cpanel?cpanel_jsonapi_module=Fileman&cpanel_jsonapi_func=listfullbackups&cpanel_jsonapi_apiversion=1” because of an error: Could not connect to '10.2.34.41:2083': Connection refused at /usr/local/cpanel/Cpanel/HTTP/Client.pm line 115, <STDIN> line 1. Cpanel::HTTP::Client::request(Cpanel::HTTP::Client=HASH(0x10bfbb0), "GET", "https://10.2.34.41:2083/json-api/cpanel?cpanel_jsonapi_module"..., HASH(0x10bfd18)) called at /usr/local/cpanel/scripts/getremotecpmove line 325 scripts::getremotecpmove::get_current_backups("10.2.34.41", "cptest", "cpanel1") called at /usr/local/cpanel/scripts/getremotecpmove line 128 scripts::getremotecpmove::fetch_acct_by_cpanel(__CPANEL_HIDDEN__, __CPANEL_HIDDEN__, __CPANEL_HIDDEN__, __CPANEL_HIDDEN__, __CPANEL_HIDDEN__, __CPANEL_HIDDEN__, __CPANEL_HIDDEN__, __CPANEL_HIDDEN__) called at /usr/local/cpanel/scripts/getremotecpmove line 58 scripts::getremotecpmove::script("scripts::getremotecpmove", "10.2.34.41", "cptest") called at /usr/local/cpanel/scripts/getremotecpmove line 31 

Description 

This issue is often seen when the server where you are running the transfer from has the 3rd party CSF firewall installed.

The issue is caused by the fact that the default CSF installation does not allow TCP outbound connections on port 2083 which is required for this feature to work.

Workaround

Check the TCP_OUT setting for CSF:

# grep ^TCP_OUT /etc/csf/csf.conf
TCP_OUT = "20,21,22,25,37,43,53,80,110,113,443,587,873,993,995,2086,2087,2089,2703"

If port 2083 is missing from the list, as in the example above, you will need to add the port to allow the connection.