Department of Engineering

The CUED ftp server

Introduction

CUED currently runs an anonymous ftp server called ftp.eng.cam.ac.uk. There are some explanations of terminology here.

This document covers a number of issues:

• Arrangements for publishing and submission via ftp
• Publishing files
• Allowing file uploads
• Web upload mechanism
• Retrieving uploaded data
• SMB (Windows) access to ftp data

This ftp server does not permit any authenticated connections - you cannot use a CUED account name and password to connect to it: all connections are anonymous. If you need to do a file transfer as a "real" (authenticated) user, then you will need to use secure ftp (eg sftp).

Arrangements for publishing and submission of material via ftp

There are four kinds of file transfer that are supported by this server:

• (permanent) anonymous download (publishing) of material (requiring operator set up)
• temporary anonymous download (publishing) of material (set up by end users, using the ftppub command)
• anonymous upload (submission) of material, accessible locally by the members of a specified unix group (requiring operator set up)
• anonymous upload (submission) of material, accessible locally by a specific user, (set up by the user, using the ftpupload command.

Publishing files

If you wish to permanently publish material on our anonymous ftp server, you will need to discuss your requirements with the operators.

If you wish to temporarily make some material available to be fetched CUED by a remote site (and are prepared to make it publicly visible - anyone could make a copy of it), then you should use the ftppub command (currently available only on gate) which will copy a file into the anonymous ftp filespace.

If the user spqr1 runs the command

ftppub afile.txt

Files that have been published in this way will be deleted some time later - the current default is after 14 days, but this period may become shorter if the filespace becomes full.

Allowing file uploads

File uploads (ie submission of files onto our system by remote users) are permitted, but under a number of restrictions:

• files that have been uploaded are not visible to or downloadable by ftp users - only CUED users logged into the teaching system can access them.
• uploaded files will be deleted some time later (the same arrangements applying as for files published with ftppub).
• uploaded files will only be accessible to specific CUED users - upload directories are named after either a user or a unix group; in the former case only that user will have access, in the latter, only members of that group.
• the directories to which uploads are permitted are not themselves visible for inspection by remote anonymous ftp users; it is possible access them, provided the remote user knows the correct name, but browsing of the available directories is not possible.

If the user spqr1 uses the ftpupload command on the teaching system (currently available only on gate) to create an upload directory, then remote users who connect to ftp.eng.cam.ac.uk will be able to change directory to /pub/upload/user/spqr1 and upload files to it.

If an upload directory has been created for the unix group cuedpeople, then remote users who connect to ftp.eng.cam.ac.uk will be able to change directory to /pub/upload/cuedpeople and upload files to it.

Remote users will need to be told the exact name of the directory that they need to use, as it won't be visible to them until they access it directly (browsing of the upload directories is not permitted).

Web upload mechanism

Additionally it is possible for remote users to use a web client rather than an ftp client to upload files onto the server. It is thus possible for a user of the CUED system to create a web page containing a form which invites remote users to submit data which the CUED user can then retrieve from the ftp server.

In the simplest case, the following urls will generate a trivial web page containing an upload form for accessing the upload space for user sqpr1 and for the unix group cuedpeople respectively:

http://ftp.eng.cam.ac.uk/upload-form.php?uploaddir=spqr1&type=user

http://ftp.eng.cam.ac.uk/upload-form.php?uploaddir=cuedpeople&type=group

It is, however, expected that people may wish to embed an upload form in a web page that they control (and to have success and failure resulting in redirects to web pages they control). There is a web page describing all the upload form facilities.

Retrieving uploaded data

If the user spqr1 creates an upload directory, and a remote user submits the file afile.txt to it, that file will be visible to spqr1 on the teaching system as /misc/anonftp/upload/user/spqr1/afile.txt

If a group upload directory for the unix group cuedpeople is created, and a remote user submits the file afile.txt to it, that file will be visible to members of the cuedpeople group on the teaching system as /misc/anonftp/upload/cuedpeople/afile.txt

Accessing published data

SMB (Windows) access to ftp data

Anyone with a CUED account can access the SMB share \\ftp.eng.cam.ac.uk\anonftp which will make all of the anonymous ftp data filesystem visible on their client. You will need to use your Teaching System username and password (if prompted for them).

Within that share, the following folders are likely to be of particular interest:

• \pub : the top level of the anonymous ftp archive
• \pub\user : contains user directories produced by the ftppub command (ie published data)
• \pub\upload : contains group upload directories
• \pub\upload\user : contains user upload directories

The latter two locations will not permit inspection of available directories - people wishing to access them will need to know their names in advance.

SMB shares are accessible from Windows clients as documented in Microsoft KnowledgeBase article 308582.

SMB clients exist for other operating systems, including smbfs and smbclient for Linux.