Using %Net.SSH.Session to do scp

Why not use SFTP for that?

The following method shows how you can get a list of the files on a server, via SFTP:

Method SFTPDir(ftpserver, username, password) As %Status
{
    set ssh = ##class(%Net.SSH.Session).%New()
    do ssh.Connect(ftpserver)
    do ssh.AuthenticateWithUsername(username,password)
    do ssh.OpenSFTP(.sftp)
    do sftp.Dir(".",.files)
    set i=0
    while $data(files(i))
    {
        write $listget(files(i),1),!
        set i=i+1
        // set st = sftp.Get(files(i), "C:\Temp\myfile.ext")
    }
    quit $$$OK
}

To download file(s) uncomment the line. Documentation.

Presumably, it's a security issue. Check effective UID and GID of your Caché processes. To do it, you may check parameters.isc file from Caché install directory for lines like these: 

security_settings.cache_user: cacheusr
security_settings.cache_group: cacheusr

Unlikely user cacheusr has access rights to other user's home directory.

csession processes are the exception from others as they inherit calling user's UID.

IMHO, it's better to use some neutral folder for file exchange, e.g. "/tmp/myexchange", as in this case it's much easier to establish appropriate assess rights for each side involved in exchange.

P.S. UNIX® Users, Groups and Permissions stuff is well-documented, see:  http://docs.intersystems.com/latest/csp/docbook/DocBook.UI.Page.cls?KEY…