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When connecting through a firewall and over a VPN, the proxy parameters for FTPLOGON are added but do not work. What should I try?

The following example from a Robo-FTP user describes a proxy server problem and the steps taken to solve it.

This is the scenario:

Firewall IP Address = 55.555.5.55
Firewall User Name = [email protected]
Firewall Password = G0344hj7
Remote Site IP Address = 111.111.1.11
Remote Site User Name = ANDY
Remote Site Password = T23r45J

It appears that the FTP command connecting to the remote site must use the proxy settings in order to get through the firewall, as in:

FTPLOGON "111.111.1.11" /user=ANDY /pw=T23r45J /proxy="55.555.5.55" /[email protected] /proxypw=G0344hj7

But this does not work. The firewall logon does more than activate a session between the user and the firewall. The following command:

FTPLOGON "55.555.5.55" /[email protected] /pw=G0344hj7

logs on to the firewall ("55.555.5.55"). The user name ([email protected]) causes the firewall to establish a ftp connection with the remote ftp site (111.111.1.11) over a VPN.

The problem is that no logon to the directory has been issued. Sending:

FTPLOGON "111.111.1.11" /user=ANDY /pw=T23r45J

will result in an FTP connection already established error because a ftp session has already been established with "111.111.1.11". The following commands:

FTPCMD "USER ANDY"
FTPCMD "PASS T23r45J"

will connect to the remote site. Note that one or both of these may return a syntax error or command not recognized error even though they work.

Article last updated: 2021-10-29

Tags: FTPLOGON, Robo-FTP, Proxy Server, Firewall