SFTP does not have the same anonymous access method as FTP, but it is possible to enable anonymous access without authentication.
The SFTP protocol works over the SSH2 transport layer, and authentication is also done using SSH2 protocol. SSH Tectia Server can be configured to allow a named user, for instance "anonymous", to log in without any authentication. It is also possible to restrict the login to a certain range of IP addresses, or to a certain interface on the server (see server admin manual for details).
It is possible to restrict the access for this user by chrooting the sftp session and denying terminal, command, and tunneling access. The user's ability to download and upload files depends on the operating system level permissions on files and directories. If upload is permitted, it is recommended to have the directories with write access on a separate file system, so that it is not possible for the anonymous user to harm the system by filling up file systems that are used by the system or by other users.