If you want to provide anonymous UUCP access to your system, you first have to set up a special account for it as described above. A common practice is to give it a login name and a password of uucp.
In addition, you have to set a few of the security options for unknown systems. For instance, you may want to prohibit them from executing any commands on your system. However, you cannot set these parameters in a sys file entry, because the system command requires the system's name, which you don't have. Taylor UUCP solves this dilemma through the unknown command. unknown can be used in the config file to specify any command that can usually appear in a system entry:
This will restrict unknown systems to downloading files from below the pub directory and uploading files to the incoming directory below /var/spool/uucppublic. The next line will make uucico ignore any requests from the remote system to turn on debugging locally. The last two lines permit unknown systems to execute rmail; but the command path specified makes uucico look for the rmail command in a private directory named anon-bin only. This allows you to provide some special rmail that, for instance, forwards all mail to the super-user for examination. This allows anonymous users to reach the maintainer of the system, but prevents them at the same time from injecting any mail to other sites.
To enable anonymous UUCP, you must specify at least one unknown statement in config. Otherwise uucico will reject any unknown systems.