critical impact:

scp - OpenSSH scp not compatible with scp2 (CrCh352)

Problem description

The scp (secure copy) command on HP-UX is not compatible with the version on Tru64 UNIX.

If you try to use the scp command on HP-UX to copy a file to Tru64 UNIX, the command will fail with the following error message:

    scp: FATAL: Executing ssh1 in compatibility mode failed (Check
    that scp1 is in your PATH).

This is a known scp incompatibility between OpenSSH and SSH Tectia. HP-UX uses OpenSSH, an open source SSH. Tru64 UNIX uses an SSH based on SSH Tectia, a commercial SSH from the original developers of SSH.

The reason for the incompatibility is that the two versions of scp use different protocols. The HP-UX scp is scp1, which uses the SCP1 protocol. The Tru64 UNIX scp is scp2, which uses the SFTP protocol. When scp2 gets an SCP1 request, it tries to handle the request by executing the scp1 command and that fails if scp1 is not installed.

The problem does not exist when copying the other way, that is, from Tru64 UNIX to HP-UX, because scp2 on Tru64 UNIX communicates directly with the sftpd daemon on HP-UX and bypasses the HP-UX scp1 completely.

Identifiers

scp

Old behavior

scp file remote_host:remote_dir

See also

• Background information on command and utilities impacts
• Background information on security related issues impacts
• scp2(1)

Solution description

To securely copy files from HP-UX to Tru64 UNIX, either use sftp or pipe the output of tar through ssh.

New behavior

tar cf - file | (ssh remote_host "cd remote_dir; tar xf -")

See also

• scp(1)

Problem summary