[rdiff-backup-users] If ssh port is not 22, how does rdiff-backup specify this in command line?

[cyclops]

 have a question.

If my server's ssh port is other port than the default 22.

When use rdiff-backup,  how to specify the port ssh use with
command line?

I read the man page, can not find a option to do this.

Any idea for this?

Thanks very much!