You have to write it inside quotes (i.e. 'copy_perms'), but in that case, that an argument is also required, you can use the fat arrow: copy_perms => 1.

In any case, note that the copy_perms feature is exclusive of Net::SFTP::Foreign. Net::SFTP does not support it.

In order to know the software used, you can just telnet to the SSH port and it will tell you. For instance:

$ telnet localhost 22
Trying ::1...
Connected to localhost.localdomain.
Escape character is '^]'.
SSH-2.0-OpenSSH_5.9p1 Debian-2ubuntu2
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