Bacula 1.36 User's Guide |
Using Stunnel of Comm Encryption | Index | Firewalls
# Bacula Security Issues The Clients (bacula-fd) must run as root to be able to access all the system files. It is not necessary to run the Director as root. It is not necessary to run the Storage daemon as root, but you must ensure that it can open the tape drives, which are often restricted to root access by default. You should restrict access to the Bacula configuration files, so that the passwords are not world-readable. The Bacula daemons are password protected using CRAM-MD5 (i.e. the password is not sent across the network). This will ensure that not everyone can access the daemons. It is a reasonably good protection, but can be cracked by experts. If you are using the recommended ports 9101, 9102, and 9103, you will probably want to protect these ports from external access using a firewall and/or using tcp wrappers (etc/hosts.allow). Currently all data that is sent across the network is unencrypted. As a consequence, unless you use ssh or stunnel for port forwarding, it is not recommended to do a backup across an insecure network (e.g. the Internet). In a future version, we plan to have ssl encryption built-in. You should ensure that the Bacula working directories are readable and writable only by the Bacula daemons. If you are using MySQL it is not necessary for it to run with root permission. The default Bacula grant-mysql-permissions script grants all permissions to use the MySQL database without a password. If you want security, please tighten this up! Don't forget that Bacula is a network program, so anyone anywhere on the network with the console program and the Director's password can access Bacula and the backed up data. You can restrict what IP addresses Bacula will bind to by using the appropriate DirAddress, FDAddress, or SDAddress records in the respective daemon configuration files. ## Configuring and Testing TCP Wrappers with Bacula TCP Wrappers are implemented if you turn them on when configuring (./configure --with-libwrap). With this code enabled, you may control who may access your daemons. This control is done by modifying the file: /etc/hosts.allow. The program name that Bacula uses when applying these access restrictions is the name you specify in the daemon configuration file. You must not use the twist option in your /etc/hosts.allow or it will terminate the Bacula daemon when a connection is refused. Dan Languille has provided the following information on configuring and testing TCP wrappers with Bacula. If you read hosts_options(5), you will see an option called twist. This option replaces the current process by an instance of the specified shell command. Typically, something like this is used:
    ALL : ALL \
     : severity auth.info \
     : twist /bin/echo "You are not welcome to use %d from %h."
The libwrap code tries to avoid twist if it runs in a resident process, but that test will not protect the first hosts_access() call. This will result in the prcess (e.g. bacula-fd, bacula-sd, bacula-dir) being terminated if the first connection to their port results in the twist option being invoked. The potential, and I stree potential, exists for an attacker to prevent the daemons from running. This situation is eliminated if your /etc/hosts.allow file contains an appropriate ruleset. The following example is sufficent:
    undef-fd : localhost : allow
    undef-sd : localhost : allow
    undef-dir : localhost : allow

    undef-fd : ALL : deny
    undef-sd : ALL : deny
    undef-dir : ALL : deny
You must adjust the daemon names to those found in the respective daemon configuration files. In these examples, the Director is undef- dir, the Storage Daemon is undef-sd, and the File Daemon is undef-fd. Adjust to suit your situation. The above example rules assume that the SD, FD, and DIR all reside on the same box. If you have a remote FD client, then the following ruleset on the remote client will suffice:
    undef-fd : director.example.org : allow
    undef-fd : ALL : deny
where director.example.org is the host which will be contacting the client (ie. the box on which the Bacula Director daemon runs). The use of "ALL : deny" ensures that the twist option (if present) is not invoked. To properly test your configuration, start the daemon(s), then attempt to connect from an IP address which should be able to connect. You should see something like this:
    $ telnet undef 9103
    Trying 192.168.0.56...
    Connected to undef.example.org.
    Escape character is '^]'.
    Connection closed by foreign host.
    $
This is the correct response. If you see this:
    $ telnet undef 9103
    Trying 192.168.0.56...
    Connected to undef.example.org.
    Escape character is '^]'.
    You are not welcome to use undef-sd from xeon.example.org.
    Connection closed by foreign host.
    $
then twist has been invoked and your configuration is not correct and you need to add the deny statement. It is important to note that your testing must include restarting the daemons after each connection attempt. You can also tcpdchk(8) and tcpdmatch(8) to validate your /etc/hosts.allow rules. Here is a simple test using tcpdmatch:
    $ tcpdmatch undef-dir xeon.example.org
    warning: undef-dir: no such process name in /etc/inetd.conf
    client: hostname xeon.example.org
    client: address 192.168.0.18
    server: process undef-dir
    matched: /etc/hosts.allow line 40
    option: allow
    access: granted
If you are running Bacula as a standalone daemon, the warning above can be safely ignored. Here is an example which indicates that your rules are missing a deny statement and the twist option has been invoked.
    $ tcpdmatch undef-dir 10.0.0.1
    warning: undef-dir: no such process name in /etc/inetd.conf
    client: address 10.0.0.1
    server: process undef-dir
    matched: /etc/hosts.allow line 91
    option: severity auth.info
    option: twist /bin/echo "You are not welcome to use
      undef-dir from 10.0.0.1."
    access: delegated
## Running as non-root Security advice from Dan Languille:
It is a good idea to run daemons with the lowest possible privileges. In other words, if you can, don't run applications as root which do not have to be root. The Storage Daemon and the Director Daemon do not need to be root. The File Daemon needs to be root in order to access all files on your system. In order to run as non-root, you need to create a user and a group. Choosing `bacula` as both the user name and the group name sounds like a good idea to me. The FreeBSD port creates this user and group for you (actually, as I write this, the port doesn't do that, but it soon will). Here is what those entries looked like on my FreeBSD laptop:
    bacula:*:1002:1002::0:0:Bacul Daemon:/var/db/bacula:/sbin/nologin
I used vipw to create this entry. I selected a User ID and Group ID of 1002 as they were unused on my system. I also created a group in /etc/group:
    bacula:*:1002:
The bacula user (as opposed to the Bacula daemon) will have a home directory of `/var/db/bacula` which is the default location for the Bacula database. Now that you have both a bacula user and a bacula group, you can secure the bacula home directory by issuing this command:
    chown -R bacula:bacula /var/db/bacula/
This ensures that only the bacula user can access this directory. It also means that if we run the Director and the Storage daemon as bacula, those daemons also have restricted access. This would not be the case if they were running as root. It is important to note that the storage daemon actually needs to be in the operator group for normal access to tape drives etc (at least on a FreeBSD system, that's how things are set up by default) Such devices are normally chown root:operator. It is easier and less error prone to make Bacula a member of that group than it is to play around with system permissions.
Starting the Bacula daemons
To start the bacula daemons on a FreeBSD system, issue the following command:
    /usr/local/etc/rc.d/bacula.sh start
To confirm they are all running:
    $ ps auwx | grep bacula

    root 63416 0.0 0.3 2040 1172 ?? Ss 4:09PM 0:00.01
        /usr/local/sbin/bacula-sd -v -c /usr/local/etc/bacula-sd.conf

    root 63418 0.0 0.3 1856 1036 ?? Ss 4:09PM 0:00.00
        /usr/local/sbin/bacula-fd -v -c /usr/local/etc/bacula-fd.conf

    root 63422 0.0 0.4 2360 1440 ?? Ss 4:09PM 0:00.00
        /usr/local/sbin/bacula-dir -v -c /usr/local/etc/bacula-dir.conf
Using Stunnel of Comm Encryption | Index | Firewalls
Bacula 1.36 User's Guide The Network Backup Solution | Copyright © 2000-2004 Kern Sibbald and John Walker