Reviewing TCP/IP port usage

The TCP/IP Port Usage page appears.

Each active host whose connection type is Direct Internet Access or VPN is interrogated for name and IP address and inbound and outbound port usage.

The information given is intended for the firewall administrator.  Each host's TCP/IP protocol, address, and inbound and outbound port usage are listed. If an application proxy has been configured, it is also listed. The inbound ports can be adjusted within Cleo LexiCom, but modifications can affect server-side or AS2 trading partner configuration. The outbound ports are dictated by the server.

For FTP, the command port and the data ports are distinguished in the report.

• FTP/s (Explicit) vs. FTP/s (Implicit)
  • For FTP/s (Explicit), the command port is initially clear text commands. The SSL handshake does not start until the client issues an AUTH SSL command and the server responds affirmatively, after which commands are encrypted.
  • For FTP/s (Implicit), the SSL handshake starts immediately once the command port is opened, after which all commands are encrypted.
• Active (a.k.a. Port) Mode vs. Passive Mode
  • In passive mode, the FTP server (host) picks a new data port dynamically for each transfer. If this is a well-known site, the known outbound data port range is listed; otherwise, ?-? is shown and you will need to contact the server administrator for the range.
  • In active mode, the FTP client (LexiCom) picks a new inbound data port dynamically from the range listed for each transfer.

For HTTP, commands and data are sent across the same port.