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Re: [Q] create account which can only transfer file use SSH????

On January 7, 2005 08:17 am, mcclnx mcc wrote:
> We have Redhat AS 2.1 nad 3.0 installed on servers.
> Due to security reason, we disable FTP and TELNET.
> Server onlly support SSH.
> We plan to create a account which can ONLY login and
> transfer data use scp or winscp on PC site (similiar
> to FTP function).

Many people are mistaken in that they think that just because they use
SSH, the system is magically more secure.  This is simply false.  You
can actually make your system *more* secure using a good FTP server
(ProFTPd is a good candidate).  Unless you go through a lot of
contortions, ssh is simply too wide open and you trust the user a lot
more than you should.

Problem 1.  You can't easily set up an upload-only directory and a
download-only directory.  If you can't do this, if anybody gets the
password, you've potentially become a porn/warez site.

Problem 2.  Because of 1, you could easily set yourself up for a DoS
attack.  A user with ssh access can write to any world-writable area.
This includes /var and /var/tmp.  They could fill those partitions and
block all your incoming mail and many apps would fail because all their
temp file creations would fail.

We really need FTP configuration abilities built into scp...

The only disadvantage of FTP is the unencrypted data and control
channels.  We mitigate those risks by using gpg to encrypt the files
first and setting up restricted areas.  Overall, I'm convinced we're
more secure than hacking ssh to restrict access.


Ed Wilts, RHCE
Mounds View, MN, USA
mailto:ewilts ewilts org
Member #1, Red Hat Community Ambassador Program

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