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Authentication is done using your SLAC Unix username and password. Since SSH authentication is used, passwordless GSSAPI also works. GSSAPI is used if you have already done a local kinit on your desktop or laptop, and therefore have a SLAC Unix Kerberos Ticket Granting Ticket, or TGT, as seen with klist, and also have the correct SSH client configuration which attempts to use GSSAPI.
SSHFS uses the SFTP protocol and SSH authentication. See https://github.com/libfuse/sshfs for more information.
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