ftp port command syntax (step-by-step)

Port 20 is assigned to FTP data. Unfortunately, most FTP data sessions do not use port 20. This tip will teach you how to use the port command and decode port data.

You may already be aware that the default port used by FTP (File Transfer Protocol) commands is 21. You may also be aware that FTP data is assigned to port 20. Unfortunately, port 20 is not used for most FTP data sessions.

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ftp port command syntax

You've just taken a look at the FTP session you were using, and you saw that a PORT command had crossed the wire. You noticed the most peculiar command sequence when you looked at the decode:

PORT 10,1,0,2,2,41

Why does this matter? Let's start by examining the PORT command's goal. The numbers that follow the command will then be decoded.

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The command PORT Two port number values are used in FTP communications: one for data transfer and one for commands (port 21 by default). The PORT command is useful in this situation.

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An FTP client sends the PORT command to create a secondary connection (address and port) for data transmission. Port 20 is used for data in some FTP implementations, but this is the exception rather than the rule. Data that crosses over a dynamic port number is frequently visible in traces; according to IANA, this range should be between 49152 and 65535, but it's more likely that your application is using something just above 1024, which used to be the dynamic port number area.

Figure 1 displays an overview.

The PORT command, which specifies the port the client will be listening on for the data channel connection, is sent by an FTP client to the FTP server. The server uses that TCP port value to create a new TCP connection with the client after receiving the PORT command.

Multiple PORT commands may be issued during a single FTP session because directory listings and file GET and PUT operations require the establishment of a new data channel.

FTP open

includes Windows Server 2022, Windows Server 2019, Windows Server 2016, Windows Server 2012 R2, and Windows Server 2012.

Syntax

open <computer> [<port>]

How do I connect to FTP in Chrome?

In Chrome, FTP support is all but gone. The pandemic delayed the removal of FTP, but it is now disabled by default and will be gone entirely very soon.

For the time being, you can re-enable FTP by visiting chrome:/flags.

However, you should seek out an alternative approach, such as a specialized FTP client (FileZilla, Cyberduck, etc.).

host

Immediately following a successful authentication negotiation, the client tries to negotiate encryption (data and command protection level of private).

Contains the host's name that you are connecting to. Specify the host's IP address or host name. The host may be a distant host or a host on your computer. As stated in the support for scope information section of the z/OS Communications Server: IPv6 Network and Application Design Guide, you can provide scope information along with the host name or IP address when using IPv6 link-local addresses.