Skip to main content.

Filesharing with chrooted SFTP

2014-02-12

Live demo in BSD Now Episode 024 | Originally written by TJ for bsdnow.tv | Last updated: 2014/05/08

So you've followed our SSH tutorial and now you're ready to hand out accounts to your friends, right? Well, there are times when you want to securely share files with them, but don't want them having shell access to your server. OpenSSH includes SFTP, the secure file transfer protocol, which provides both authentication and encryption. Normally, you need to give a user an SSH login for them to be able to transfer files via SFTP, but there’s also a useful option to disallow shell access and only let them transfer files. What's more, you can lock them to a certain directory so they can't browse your filesystem. This tutorial will show you how to do just that. I’m assuming you already have sshd configured and running.

Let's create a new user for them to use and edit the sshd_config file to chroot them.

# adduser

Username: gnub
Full name: Some Random GNUb
Uid (Leave empty for default):
Login group [gnub]:
Login group is gnub. Invite gnub into other groups? []:
Login class [default]:
Shell (sh csh tcsh bash rbash nologin) [sh]: nologin
Home directory [/home/gnub]:
Home directory permissions (Leave empty for default):
Use password-based authentication? [yes]:
Use an empty password? (yes/no) [no]:
Use a random password? (yes/no) [no]:
Enter password:
Enter password again:
Lock out the account after creation? [no]:
Username   : gnub
Password   : *****
Full Name  : Some Random GNUb
Uid     : 1004
Class     :
Groups   : gnub
Home       : /home/gnub
Home Mode  :
Shell     : /usr/sbin/nologin
Locked   : no
OK? (yes/no): yes
adduser: INFO: Successfully added (gnub) to the user database.
Add another user? (yes/no): no
Goodbye!

Take note of the "nologin" shell - that's not the default. Next we edit the SSH configuration:

# vi /etc/ssh/sshd_config

Add something like this to the bottom:

Match User gnub
    PasswordAuthentication yes
    ChrootDirectory %h
    ForceCommand internal-sftp
    AllowTcpForwarding no
    AllowAgentForwarding no
    PermitTunnel no
    PermitTTY no
    X11Forwarding no

Restart the daemon.

# /etc/rc.d/sshd restart

Next, we set some permissions and make a directory for them to actually put files in.

# chown root:gnub /home/gnub
# mkdir /home/gnub/files
# chown gnub:gnub /home/gnub/files

Now you can give your friend the SFTP login and they will be locked in the home directory, but able to upload and download things to and from the "files" directory. If they try to login via SSH to get a shell, they should get the error:

This service allows sftp connections only.

Too bad for them.

Latest News

How did you get into BSD?

2014-11-26

We've got a fun idea for the holidays this year: just like we ask during the interviews, we want to hear how all the viewers and listeners first got into BSD. Email us your story, either written or a video version, and we'll read and play some of them for...

EuroBSDCon 2014

2014-09-18

As you might expect, both Allan and Kris will be at EuroBSDCon this year. They'll be busy hunting down various BSD developers and forcing them to do interviews, but don't hesitate to say hi if you're a listener!...

BSDCan 2014

2014-04-30

We just wrapped up episode 35 after having some horrible audio issues. Sorry about the quality being lower than usual, we did the best we could given the circumstances. Next week we've got a normal episode, but the following week Allan and Kris will be at BSDCan. That week will...

AsiaBSDCon 2014

2014-03-05

Both Allan and Kris will be going to AsiaBSDCon this year, so episode 28 will be shorter than usual. We'll be back the following week with a huge episode. Hopefully they can get some interviews there!...


Episode 068: Just the Essentials

2014-12-17

Direct Download: Video | HD Video | MP3 Audio | OGG Audio | Torrent This episode was brought to you by Headlines More BSD conference videos We mentioned it a few times, but the "New Directions in Operating Systems" conference was held in November in the UK The presentations videos are now online, with a few...

Episode 067: Must Be Rigged

2014-12-10

Direct Download: Video | HD Video | MP3 Audio | OGG Audio | Torrent This episode was brought to you by Headlines Bitrig 1.0 released If you haven't heard of it, Bitrig is a fork of OpenBSD that started a couple years ago According to their FAQ, some of their goals include: only supporting modern hardware...

Episode 066: Conference Connoisseur

2014-12-03

Direct Download: Video | HD Video | MP3 Audio | OGG Audio | Torrent This episode was brought to you by Headlines More BSD presentation videos The MeetBSD video uploading spree continues with a few more talks, maybe this'll be the last batch Corey Vixie, Web Apps in Embedded BSD Allan Jude, UCL config Kip Macy, iflib While we're...

Episode 065: 8,000,000 Mogofoo-ops

2014-11-26

Direct Download: Video | HD Video | MP3 Audio | OGG Audio | Torrent This episode was brought to you by Headlines Even more BSD presentation videos More videos from this year's MeetBSD and OpenZFS devsummit were uploaded since last week Robert Ryan, At the Heart of the Digital Economy FreeNAS & ZFS, The Indestructible Duo -...