Jun 2, 2012

Setup VSFTPD with custom multiple directories and (virtual) users accounts on Ubuntu (no database required)

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Julien Bourdeau

— 1081 words

I wanted to install an FTP server on my servers, I checked online and it turned out that VSFTPD is the most secure one, so I began to installing it.

I've been through many tutorials but couldn't find any in full detail, so decided to write my own. I set up VSFTPD on my personal server, wrote the tutorial step by step then followed my own tutorial to deploy VSFTPD on my production dedicated server.

How to do it

  • Install vsftpd and a PAM library
  • Edit /etc/vsftpd.conf and /etc/pam.d/vsftpd
  • Create user accouts with custom directories (in /var/www/ for example)
  • Set directories with the correct chmod and chown
  • Create a admin user with full access to the server
  • Troubleshoot

1. Install vsftpd (Very Secure FTP Deamon) and libpam-pwdfile to create virtual users

I wanted to create FTP users but I didn't want to add local unix users (no shell access, no home directory and so on). A PAM (Pluggable Authentication Modules) will help you create virtual users.

1sudo apt-get install vsftpd libpam-pwdfile

2. Edit vsftpd.conf

First you need to back up the original file

1sudo mv /etc/vsftpd.conf /etc/vsftpd.conf.bak

Then create a new one

1sudo vim /etc/vsftpd.conf

Copy and paste the following lines. The file should ONLY contain these lines:

 1 
 2listen=YES
 3anonymous_enable=NO
 4local_enable=YES
 5write_enable=YES
 6local_umask=022
 7nopriv_user=vsftpd
 8virtual_use_local_privs=YES
 9guest_enable=YES
10user_sub_token=$USER
11local_root=/var/www/$USER
12chroot_local_user=YES
13hide_ids=YES
14guest_username=vsftpd

3. Register virtual users

To register a user you use htpasswd, so I assume you have apache2 working on your server. Create a vsftpd folder then put configuration files in it.

1sudo mkdir /etc/vsftpd

then

1sudo htpasswd -cd /etc/vsftpd/ftpd.passwd user1
  • -c means that we'll create the file if it's not existing yet
  • -d forces MD5, you need it on ubuntu 12.04, just use it always The command will prompt for a password.

If you want to add new users afterwards:

1sudo htpasswd -d /etc/vsftpd/ftpd.passwd user2

4. Configure PAM in /etc/pam.d/vsftpd

Again, you need to back up the orignal file

1sudo mv /etc/pam.d/vsftpd /etc/pam.d/vsftpd.bak

and create a new one

1sudo vim /etc/pam.d/vsftpd

Copy and paste these 2 lines (this should be the only content). I insist only these 2 lines, I wasted a lot of time keeping the originals and just added these.

1auth required pam_pwdfile.so pwdfile /etc/vsftpd/ftpd.passwd
2account required pam_permit.so

5. Create a local user without shell access

1sudo useradd --home /home/vsftpd --gid nogroup -m --shell /bin/false vsftpd

You can check that it's been created with the id command: id vsftpd. We define the user with the /bin/false shell because of the check_shell parameter (even if you don't use it).

When the end user connects to the FTP server, they will be used for rights and ownership: chmod and chown.

6. Restart vsftpd

The common way is using init.d like all deamon

1sudo /etc/init.d/vsftpd restart

In Ubuntu 12.04 there is something new with services. It worked on my 12.04 but not on my 10.04 one. To be honest I'm not a Linux expert (yet) so I can't explain why. Something to do with Upstart I think.

1sudo service vsftpd restart

7. Create directories

According to your configuration all users will be placed into this folder: /var/www/user1.

You need to create them with particular rights: the root folder cannot be writable!

  • Folder / [root = /var/www/user1] => 555
    • Folder www [ /var/www/user1/www ] => 755
    • Folder docs [ /var/www/user1/docs ] => 755

The user cannot create files or folders in the root directory.

In vsftpd.conf we have chroot_local_user=YES so the user can't see anything outside of his folder. To him, the server looks like this:

login ftp vsftpd chroot

So just run these commands:

1mkdir /var/www/user1
2chmod -w /var/www/user1
3mkdir www/user1/www
4chmod -R 755 /var/www/user1/www
5chown -R vsftpd:nogroup /var/www/user1

The /var/www/user1 folder has to exist or connection will fail.

Right now you can try to connect with your FTP client and it will succeed! If it doesn't you can check the troubleshooting part.

8. Create an Admin user to access the entire server

To create an admin user we need to register a new user with htpasswd.

Before we do so, I'll advise you to check into the /etc/ftpusers file that define certain users that are not allowed to connect with ftp. I think it's only for local users and not virtual users but just in case don't choose a name contained in this file. Let's be honest, vsftpd is complicated enough!

1sudo htpasswd -d /etc/vsftpd/ftpd.passwd theadmin

Now we need to add a new line into /etc/vsftpd.conf

1chroot_list_enable=YES

This means that your user will be placed into their folder (as a jail) EXCEPT users in the /etc/vsftpd.chroot_list

Let's create this file and add our user, the file is a simple line containing "theadmin". Add one user per line. That means you DON'T need to create a /var/www/theadmin folder, the user will login and start in /home/vsftpd.

Restart the server and you're done !

Troubleshooting

Here are some errors I encountered.

500 OOPS: vsftpd: refusing to run with writable root inside chroot ()

Your root directory is writable, this is not allowed. Check part 7 for more information, you need to create a 555 root and 755 subfolders

500 OOPS: cannot change directory:/var/www/theadmin if the folder doesnt exist

The /var/www/$USER folder doesn't exist, create it with the correct rights (not writable) or add the user into the /etc/vsftpd.chroot_list (see part 8). Don't forget to restart the server.

htpasswd: cannot create file /etc/vsftpd/ftpd.passwd

The /etc/vsftpd/ folder has to be existing, htpasswd won't create it.

vsftpd restart or stop error: restart: Unknown instance

This means you can't start the deamon even if you have success message with /etc/init.d/vsftpd start. It doesn't start because your configuration is wrong. Start the tutorial again.

Sources

Here are some websites that helped me

If you want to create some sort of symlink to let your user access somewhere outside their chroot jail use mount --bind

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