Shulou(Shulou.com)06/02 Report--

As soon as you get a reinstalled server, the remote ssh is normal, but an error is reported as soon as SCP copies something:

It is confirmed that there is a scp command locally, and if there is no scp locally, the following lost connection will not be reported, so there is no scp command remotely. So just install openssh-clients on the remote server. Then why is that?

Scp principle

Scp is the implementation of rcp (remote file copy) on ssh. There is no difference between rcp and scp at the protocol level, except that rlogin is used for transmission.

Scp parses the command-line arguments, then opens a connection to the remote server, and then sets up another scp process remotely over this connection. The remote scp process can be either a source or a destination (depending on the direction in which you copy the file).

The data provider, the source, and the scp process running in source mode are later called the source side.

The destination of the data, the destination, and the scp process running in destination mode will be called the destination.

The source side reads the file and sends it to the other end through the SSH connection, and the host side receives the file through the SSH connection.

Source mode and destination mode are started with two hidden options-f (from) and-t (to).

These two parameters are only for internal use of the command, so they are not documented. In addition to these two hidden parameters, there is another hidden parameter-d, which indicates that the copied object is a directory rather than a file.

Summary

From the above principle, we can see that ssh only provides a channel, and it is the communication between scp that actually copies things, so both local and remote must have scp commands, otherwise files cannot be copied remotely.

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