At my place, we have a Linux machine where our people and outside companies can drop off and pick up data. At the moment we allow only ssh, scp, and sftp. Unfortunately, we deal with large amounts of drops and data, and people never delete the files when they are done, leading to storage problems. There is a lot of risk leaving sensitive data in a machine that can be accessed by the outside and we are already implementing data retention policies. I know this situation isn't that rare, so is there any software that was developed for managing such a situation?
I think that your underlying problem is a matter of policy and not necessarily a technical issue. Truthfully, this is an issue that I've had to deal with and the following is how we resolved the issue.
All of the files are stored in a locked down storage area on the server and the user is only ever given exactly what files they need access to. We keep the sftp logs and audit them on occasion. Disk space is not as much of a concern for us, however this matter could be resolved by an admin making a note to delete the file when the deadline passes or writing a simple script and scheduling it for that time.
While people were a bit hesitant at first, we made sure we stuck to the policy and enforced it. You could even write a simple bash script that notifies you of disk usage on your machines and automatically delete files that haven't been accessed in X amount of days.
DKNUCKLES Has a great solution depending on your size; though be sure to consider scalability - a high overhead process that works for 10 users could become a problem if it grows to 200 users.
He's also extremely poignant in pointing out that this is, in large part, a policy issue as well. How an internal IT organization decides to open its resources up to the outside world is an extremely important question that deserves a well thought out answer in today's cyber-threat environment.
That being said, there are a few technologies that may be worth mentioning, though again, depending on your size may not be applicable:
1.) A web based file sharing/a generic drop box service. This could be external (like DropBox itself), or for ease of use and increased security, could perhaps be controlled and hosted internally, with a policy driven access model
2.) A federated security model between your company and outside entities. If you're a large organization that wishes to allow for sustained interaction between your intranet, and that of a well known and trusted entity (like a supplier, subsidiary, etc.), there are federated systems that allow for cross intranet trusts (check out https://www.pingidentity.com/)
3.) Following up with DKNUCKLES recommendation, if you decide to go with a closely managed share, I might recommend the use of a DMZ'd area of the network for your special file share if you haven't considered it already. And be sure to audit the hell out of it :)
Faced with the same situation I wrote a script which deletes all files that have not been accessed for 3 months, run as a cron job.
Document sensitivity should be covered by access rights. e.g. On our system all private folders require authentication. The only practical risk, other than the human factor, is the obvious one of the system being compromised, which must be addressed separately.