scp with port number specified

Question

I\'m trying to scp a file from a remote server to my local machine. Only port 80 is accessible.

I tried:

scp -p 80 username@www.myserver.com:/root/file.t         


        

Answer 1

Unlike ssh, scp uses the uppercase P switch to set the port instead of the lowercase p:

scp -P 80 ... # Use port 80 to bypass the firewall, instead of the scp default

The lowercase p switch is used with scp for the preservation of times and modes.

Here is an excerpt from scp's man page with all of the details concerning the two switches, as well as an explanation of why uppercase P was chosen for scp:

-P port   Specifies the port to connect to on the remote host. Note that this option is written with a capital 'P', because -p is already reserved for preserving the times and modes of the file in rcp(1).

-p           Preserves modification times, access times, and modes from the original file.

Update and aside to address one of the (heavily upvoted) comments:

With regard to Abdull's comment about scp option order, what he suggests:

scp -P80 -r some_directory -P 80 ...

..., intersperses options and parameters. getopt(1) clearly defines that parameters must come after options and not be interspersed with them:

The parameters getopt is called with can be divided into two parts: options which modify the way getopt will do the parsing (the options and the optstring in the SYNOPSIS), and the parameters which are to be parsed (parameters in the SYNOPSIS). The second part will start at the first non-option parameter that is not an option argument, or after the first occurrence of '--'. If no '-o' or '--options' option is found in the first part, the first parameter of the second part is used as the short options string.

Since the -r command line option takes no further arguments, some_directory is "the first non-option parameter that is not an option argument." Therefore, as clearly spelled out in the getopt(1) man page, all succeeding command line arguments that follow it (i.e., -P 80 ...) are assumed to be non-options (and non-option arguments).

So, in effect, this is how getopt(1) sees the example presented with the end of the options and the beginning of the parameters demarcated by succeeding text bing in gray:

scp -P80 -r some_directory -P 80 ...

This has nothing to do with scp behavior and everything to do with how POSIX standard applications parse command line options using the getopt(3) set of C functions.

For more details with regard to command line ordering and processing, please read the getopt(1) manpage using:

man 1 getopt