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Anonymous ftp access using WWW

  M. Marquina and B. Pollermann CN/DCI


On occasions, users need to exchange files with external sites. Traditionally, such functionality on UNIX is offered through what is called ``anonymous ftp'' access, which consists essentially in allowing connections to a given computer without going through a formal validation mechanism (i.e. without having to supply a valid userid and password). While this mechanism is relatively secure (assuming that only file exporting is allowed - in the ``ftp'' terminology, the users may only ``get'' files), it requires a non-trivial knowledge of the operating system to install correctly on the host system providing the access. (Install it wrongly and sensitive files might become unprotected and exposed to the world.)

WWW technology offers a natural way to ``publish'' files and make them accessible to the outside world. This article presents the service proposed by CN Division to achieve such a goal.

CERN Policy

For security reasons, no anonymous ftp service is offered on any public CN Service. We discourage creating such access on your private workstation or PC for the same reasons, and even if you have to do it, we strongly recommend not to allow file imports - in the ``ftp'' terminology, that users may ``put'' files. This is because hackers often use writable FTP servers as a repository for illegal software. Systems which insist on permitting writable anonymous ftp access should be configured such that the writable directory is not readable by ``public''.

You may however export any of your files through WWW following the procedure described below.

Publishing files through WWW

CERN user files may be offered for public access from two locations: UNIX (through your afs account) and PCs (through your NICE account). This is the way to proceed:

On afs

Create in your HOME directory the ``www'' subdirectory, open this for public access by setting the adequate afs ACLs (access control list), and then install the relevant files there. We have created the `webaccess' command to make these steps:

 webaccess          creates the ~/www location 
                    and sets ACL
 webaccess file(s)  installs the indicated file(s) 
                    at the above location

From then on, your file is available under the URL:
It is useful to create an HTML file index to guide your correspondents through the different files you offer for down-loading. See an example at:


All your files are by default accessible through WWW and no special operation needs to be performed. Simply install the relevant file(s) at your HOME directory.

From then on, your file is available under the URL:
As before, a suitable index will help your correspondents to navigate through your public files.

Down-loading WWW Files

In order to fetch files from a user repository, just open the URL with a Web browser which is able to down-load the files to your disk, e.g. Mosaic or Netscape:

Open the user's file index (if it exists).
In Mosaic, activate the switch ``Load to Local Disk'' under the ``Options'' menu, or,
In Netscape, select the link by clicking on it with the right mouse button.
Open the relevant URL or simply click on the WWW link pointing to the desired file.

next up previous
Next: The `uco -home' Command Up: Desktop Computing Previous: Reading UNIX Man Pages

Michel Goossens
CN Division
Tel. 3363
Thu May 30 20:08:07 METDST 1996