Firewall/proxy for test, but which?

[Alexander Holzer]

I search proxy/firewall for the test with connection method (for FTP):
"USER user@firewalluser@hostname" / "PASS pass@firewallpass" to login.

I try Proxy+, but this program does not support this method of connection.
Only gateway with: "USER user@hostname" to login.

Thanks.

[Alexander Holzer]

I have it!
It is the correct login-sequence:

OPEN fireHostname [firePort]
USER user@firewalluser@hostname
PASS pass@firewallpass
USER user
PASS pass