Most Linux software products are available in a precompiled package format. Downloading and installing packages isn’t hard. If you need a refresher, Chapter 6, “Installing Linux Software“, covers how to do this in detail. It is best to use the latest version of VSFTPD.
When searching for the file, remember that the VSFTPD packages’ filename usually starts with the word vsftpd followed by a version number, as in vsftpd-1.2.1-5.i386.rpm for Redhat/Fedora or vsftpd_2.0.4-0ubuntu4_i386.deb for Ubuntu.
How To Get VSFTPD Started
With Fedora, Redhat, Ubunbtu and Debian You can start, stop, or restart VSFTPD after booting by using these commands:
[root@bigboy tmp]# /etc/init.d/vsftpd start [root@bigboy tmp]# /etc/init.d/vsftpd stop [root@bigboy tmp]# /etc/init.d/vsftpd restart
With Redhat / Fedora you can configure VSFTPD to start at boot you can use the chkconfig command.
[root@bigboy tmp]# chkconfig vsftpd on
With Ubuntu / Debian the sysv-rc-conf command can be used like this:
root@u-bigboy:/tmp# sysv-rc-conf on
Note: In RedHat Linux version 8.0 and earlier, VSFTPD operation is controlled by the xinetd process, which is covered in Chapter 16, “Telnet, TFTP, and xinetd“. You can find a full description of how to configure these versions of Linux for VSFTPD in Appendix III, “Fedora Version Differences.”
Testing the Status of VSFTPD
You can always test whether the VSFTPD process is running by using the netstat -a command which lists all the TCP and UDP ports on which the server is listening for traffic. This example shows the expected output.
[root@bigboy root]# netstat -a | grep ftp tcp 0 0 *:ftp *:* LISTEN [root@bigboy root]#
If VSFTPD wasn’t running, there would be no output at all.
The vsftpd.conf File
VSFTPD only reads the contents of its vsftpd.conf configuration file only when it starts, so you’ll have to restart VSFTPD each time you edit the file in order for the changes to take effect. The file may be located in either the /etc or the /etc/vsftpd directories depending on your Linux distribution.
This file uses a number of default settings you need to know about.
- VSFTPD runs as an anonymous FTP server. Unless you want any remote user to log into to your default FTP directory using a username of anonymous and a password that’s the same as their email address, I would suggest turning this off. The configuration file’s anonymous_enable directive can be set to no to disable this feature. You’ll also need to simultaneously enable local users to be able to log in by removing the comment symbol (#) before the local_enable instruction.
- If you enable anonymous FTP with VSFTPD, remember to define the root directory that visitors will visit. This is done with the anon_root directive.
anon_root=/data/directory
- VSFTPD allows only anonymous FTP downloads to remote users, not uploads from them. This can be changed by modifying the anon_upload_enable directive shown later.
- VSFTPD doesn’t allow anonymous users to create directories on your FTP server. You can change this by modifying the anon_mkdir_write_enable directive.
- VSFTPD logs FTP access to the /var/log/vsftpd.log log file. You can change this by modifying the xferlog_file directive.
- By default VSFTPD expects files for anonymous FTP to be placed in the /var/ftp directory. You can change this by modifying the anon_root directive. There is always the risk with anonymous FTP that users will discover a way to write files to your anonymous FTP directory. You run the risk of filling up your /var partition if you use the default setting. It is best to make the anonymous FTP directory reside in its own dedicated partition.
The configuration file is fairly straight forward as you can see in the snippet below where we enable anonymous FTP and individual accounts simultaneously.
# Allow anonymous FTP? anonymous_enable=YES ... # The directory which vsftpd will try to change # into after an anonymous login. (Default = /var/ftp) anon_root=/data/directory ... # Uncomment this to allow local users to log in. local_enable=YES ... # Uncomment this to enable any form of FTP write command. # (Needed even if you want local users to be able to upload files) write_enable=YES ... # Uncomment to allow the anonymous FTP user to upload files. This only # has an effect if global write enable is activated. Also, you will # obviously need to create a directory writable by the FTP user. #anon_upload_enable=YES ... # Uncomment this if you want the anonymous FTP user to be able to create # new directories. #anon_mkdir_write_enable=YES ... # Activate logging of uploads/downloads. xferlog_enable=YES ... # You may override where the log file goes if you like. # The default is shown below. xferlog_file=/var/log/vsftpd.log ...
To activate or deactivate a feature, remove or add the # at the beginning of the appropriate line.
Other vsftpd.conf Options
There are many other options you can add to this file:
- Limiting the maximum number of client connections (max_clients)
- Limiting the number of connections by source IP address (max_per_ip)
- The maximum rate of data transfer per anonymous login. (anon_max_rate)
- The maximum rate of data transfer per non-anonymous login. (local_max_rate)
Descriptions on this and more can be found in the vsftpd.conf man pages.
FTP Security Issues
FTP has a number of security drawbacks, but you can overcome them in some cases. You can restrict an individual Linux user’s access to non-anonymous FTP, and you can change the configuration to not display the FTP server’s software version information, but unfortunately, though very convenient, FTP logins and data transfers are not encrypted.
The /etc/vsftpd.ftpusers File
For added security, you may restrict FTP access to certain users by adding them to the list of users in the /etc/vsftpd.ftpusers file. The VSFTPD package creates this file with a number of entries for privileged users that normally shouldn’t have FTP access. As FTP doesn’t encrypt passwords, thereby increasing the risk of data or passwords being compromised, it is a good idea to let these entries remain and add new entries for additional security.
Anonymous Upload
If you want remote users to write data to your FTP server, then you should create a write-only directory within /var/ftp/pub. This will allow your users to upload but not access other files uploaded by other users. The commands you need are:
[root@bigboy tmp]# mkdir /var/ftp/pub/upload [root@bigboy tmp]# chmod 722 /var/ftp/pub/upload
FTP Greeting Banner
Change the default greeting banner in the vsftpd.conf file to make it harder for malicious users to determine the type of system you have. The directive in this file is.
ftpd_banner= New Banner Here
Using SCP As Secure Alternative To FTP
One of the disadvantages of FTP is that it does not encrypt your username and password. This could make your user account vulnerable to an unauthorized attack from a person eavesdropping on the network connection. Secure Copy (SCP) and Secure FTP (SFTP) provide encryption and could be considered as an alternative to FTP for trusted users. SCP does not support anonymous services, however, a feature that FTP does support.
Troubleshooting FTP
You should always test your FTP installation by attempting to use an FTP client to log in to your FTP server to transfer sample files.
The most common sources of day-to-day failures are incorrect usernames and passwords.
Initial setup failures could be caused by firewalls along the path between the client and server blocking some or all types of FTP traffic. Typical symptoms of this are either connection timeouts or the ability to use the ls command to view the contents of a directory without the ability to either upload or download files. Follow the firewall rule guidelines to help overcome this problem. Connection problems could also be the result of typical network issues outlined in Chapter 4, “Simple Network Troubleshooting“.
Tutorial
FTP has many uses, one of which is allowing numerous unknown users to download files. You have to be careful, because you run the risk of accidentally allowing unknown persons to upload files to your server. This sort of unintended activity can quickly fill up your hard drive with illegal software, images, and music for the world to download, which in turn can clog your server’s Internet access and drive up your bandwidth charges.
FTP Users with Only Read Access to a Shared Directory
In this example, anonymous FTP is not desired, but a group of trusted users need to have read only access to a directory for downloading files. Here are the steps:
1) Disable anonymous FTP. Comment out the anonymous_enable line in the vsftpd.conf file like this:
# Allow anonymous FTP? anonymous_enable=NO
2) Enable individual logins by making sure you have the local_enable line uncommented in the vsftpd.conf file like this:
# Uncomment this to allow local users to log in. local_enable=YES
3) Start VSFTP.
[root@bigboy tmp]# service vsftpd start
4) Create a user group and shared directory. In this case, use /home/ftp-users and a user group name of ftp-users for the remote users
[root@bigboy tmp]# groupadd ftp-users [root@bigboy tmp]# mkdir /home/ftp-docs
5) Make the directory accessible to the ftp-users group.
[root@bigboy tmp]# chmod 750 /home/ftp-docs [root@bigboy tmp]# chown root:ftp-users /home/ftp-docs
6) Add users, and make their default directory /home/ftp-docs
[root@bigboy tmp]# useradd -g ftp-users -d /home/ftp-docs user1 [root@bigboy tmp]# useradd -g ftp-users -d /home/ftp-docs user2 [root@bigboy tmp]# useradd -g ftp-users -d /home/ftp-docs user3 [root@bigboy tmp]# useradd -g ftp-users -d /home/ftp-docs user4 [root@bigboy tmp]# passwd user1 [root@bigboy tmp]# passwd user2 [root@bigboy tmp]# passwd user3 [root@bigboy tmp]# passwd user4
7) Copy files to be downloaded by your users into the /home/ftp-docs directory
8) Change the permissions of the files in the /home/ftp-docs directory for read only access by the group
[root@bigboy tmp]# chown root:ftp-users /home/ftp-docs/* [root@bigboy tmp]# chmod 740 /home/ftp-docs/*
- Users should now be able to log in via FTP to the server using their new usernames and passwords. If you absolutely don’t want any FTP users to be able to write to any directory, then you should set the write_enable line in your vsftpd.conf file to no:
write_enable = NO
Remember, you must restart VSFTPD for the configuration file changes to take effect.
Sample Login Session To Test Functionality
Here is a simple test procedure you can use to make sure everything is working correctly:
1) Check for the presence of a test file on the ftp client server.
[root@smallfry tmp]# ll total 1 -rw-r--r-- 1 root root 0 Jan 4 09:08 testfile [root@smallfry tmp]#
2) Connect to bigboy via FTP
[root@smallfry tmp]# ftp 192.168.1.100 Connected to 192.168.1.100 (192.168.1.100) 220 ready, dude (vsFTPd 1.1.0: beat me, break me) Name (192.168.1.100:root): user1 331 Please specify the password. Password: 230 Login successful. Have fun. Remote system type is UNIX. Using binary mode to transfer files. ftp>
- As expected, we can’t do an upload transfer of testfile to bigboy.
ftp> put testfile local: testfile remote: testfile 227 Entering Passive Mode (192,168,1,100,181,210) 553 Could not create file. ftp>
- But we can view and download a copy of the VSFTPD RPM located on the FTP server bigboy.
ftp> ls 227 Entering Passive Mode (192,168,1,100,35,173) 150 Here comes the directory listing. -rwxr----- 1 0 502 76288 Jan 04 17:06 vsftpd-1.1.0-1.i386.rpm 226 Directory send OK. ftp> get vsftpd-1.1.0-1.i386.rpm vsftpd-1.1.0-1.i386.rpm.tmp local: vsftpd-1.1.0-1.i386.rpm.tmp remote: vsftpd-1.1.0-1.i386.rpm 227 Entering Passive Mode (192,168,1,100,44,156) 150 Opening BINARY mode data connection for vsftpd-1.1.0-1.i386.rpm (76288 bytes). 226 File send OK. 76288 bytes received in 0.499 secs (1.5e+02 Kbytes/sec) ftp> exit 221 Goodbye. [root@smallfry tmp]#
- As expected, anonymous FTP fails.
[root@smallfry tmp]# ftp 192.168.1.100 Connected to 192.168.1.100 (192.168.1.100) 220 ready, dude (vsFTPd 1.1.0: beat me, break me) Name (192.168.1.100:root): anonymous 331 Please specify the password. Password: 530 Login incorrect. Login failed. ftp> quit 221 Goodbye. [root@smallfry tmp]#
Now that testing is complete, you can make this a regular part of your FTP server’s operation.
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