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# BackupPC

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BackupPC is a high-performance, enterprise-grade system for backing up Unix, Linux, WinXX, and MacOSX PCs, desktops and laptops to a server's disk. BackupPC is highly configurable and easy to install and maintain.

Given the ever decreasing cost of disks and raid systems, it is now practical and cost effective to backup a large number of machines onto a server's local disk or network storage. For some sites this might be the complete backup solution. For other sites additional permanent archives could be created by periodically backing up the server to tape.

Note that BackupPC only provides file-based backups and restores. In particular, it is not suitable out-of-the-box for "hot" database backups (although pre-backup hooks can be used to dump databases and do "cold" backups); you will need tools like xtrabackup for that purpose. Also, BackupPC only offers limited handling of opened files. Make sure to read about the limitations of BackupPC and test a backup-and-restore cycle before you actually need to resort to it for real.

## Installation

Install backuppc. Install rsync and perl-file-rsyncp if you want to use rsync as a transport, and rrdtool to display usage data in the CGI interface.

Then start/enable `backuppc.service`.

### Placing data directories on a separate partition

The BackupPC pool is stored by default under `/var/lib/backuppc`, which also serves as the home directory for the backuppc user. This path can be changed via the `$Conf{TopDir}` entry in `/etc/backuppc/config.pl`. Typical reasons are that you keep your system on a fast, but expensive and small, SSD and need to store the backups on a traditional hard disk, or that you want to keep the backup pool on a partition managed by an LVM to be able to resize to partition according to changing demands.

The documentation suggests to not change the `$Conf{TopDir}` entry, but instead use symlinks. However, be careful when doing so because package upgrades for backuppc will replace symlinks for both `/var/lib/backuppc` or any of the default subdirectories `cpool`, `pc` or `pool` by empty directories without any warning.

Thus, it is recommended to either use bind mounts in fstab instead of symlinks, or to deliberately ignore the recommendation in `/etc/backuppc/config.pl` and change `$Conf{TopDir}` nevertheless. Alternatively, use pacman's pre- and post-transaction hooks such as the following (remember to make the shell scripts executable):

    /etc/pacman.d/hooks/backuppc-restore-symlinks-post.hook

    [Trigger]
    Operation = Upgrade
    Type = Package
    Target = backuppc

    [Action]
    Description = Restore symlinks for BackupPC pool directories
    When = PostTransaction
    Exec = /etc/pacman.d/hooks/backuppc-restore-symlinks-post.sh

    /etc/pacman.d/hooks/backuppc-restore-symlinks-post.sh

    #!/usr/bin/bash

    if [ ! -d /tmp/backuppc-symlinks-cache ]; then
        exit 0
    fi

    if [ -L /tmp/backuppc-symlinks-cache/backuppc ]; then
        rmdir /var/lib/backuppc/{cpool,pc,pool,}
        mv /tmp/backuppc-symlinks-cache/backuppc /var/lib/
        echo "==> Restored /var/lib/backuppc => $(readlink /var/lib/backuppc)"
    fi

    for dir in cpool pc pool; do
        if [ -L /tmp/backuppc-symlinks-cache/$dir ]; then
            rmdir /var/lib/backuppc/$dir
            mv /tmp/backuppc-symlinks-cache/$dir /var/lib/backuppc/
            echo "==> Restored /var/lib/backuppc/${dir} => $(readlink /var/lib/backuppc/$dir)"
        fi
    done

    if [ -f /tmp/backuppc-symlinks-cache/was-running ]; then
        echo '==> BackupPC service was stopped for upgrade.'
        echo '==> Check the configuration and run `systemctl start backuppc.service` to restart the service.'
        rm -f /tmp/backuppc-symlinks-cache/was-running
    fi

    rmdir --ignore-fail-on-non-empty /tmp/backuppc-symlinks-cache &>/dev/null

    /etc/pacman.d/hooks/backuppc-restore-symlinks-pre.hook

    [Trigger]
    Operation = Upgrade
    Type = Package
    Target = backuppc

    [Action]
    Description = Stash symlinks for BackupPC pool directories
    When = PreTransaction
    Exec = /etc/pacman.d/hooks/backuppc-restore-symlinks-pre.sh

    /etc/pacman.d/hooks/backuppc-restore-symlinks-pre.sh

    #!/usr/bin/bash

    if systemctl is-active backuppc.service &>/dev/null; then
        systemctl stop backuppc.service
        mkdir -p /tmp/backuppc-symlinks-cache
        touch /tmp/backuppc-symlinks-cache/was-running
    fi

    for dir in /var/lib/backuppc/{cpool,pc,pool,}; do
        if [ -L $dir ]; then
            mkdir -p /tmp/backuppc-symlinks-cache
            mv $dir /tmp/backuppc-symlinks-cache
        fi
    done

## Apache configuration

BackupPC has a web interface that allows you to easily control it. You can access it using Apache and mod_perl or a C wrapper but other webservers like lighttpd works too. Install apache.

### Edit Apache configuration

BackupPC's web UI needs to run as the user backuppc, but Apache normally runs under the user http. There are several ways to fix this. The two demonstrated here are common for single-purpose servers (Apache is only used to serve the BackupPC UI) or for multi-purpose servers (Apache may also server other websites under the regular http user).

Setting up Apache for single-purpose use is a bit easier but not as flexible.

#### General settings

Edit `/etc/backuppc/config.pl`. Set administrator name:

    $Conf{CgiAdminUsers} = 'admin';

Next, we need to add a users file and set the admin password:

    # htpasswd -c /etc/backuppc/backuppc.users admin

The BackupPC-Webfrontend is initially configured so that you can only access it from the localhost. If you want to access it from all machines in your network, you have to edit `/etc/httpd/conf/extra/backuppc.conf`. Edit the line:

    Require ip 127.0.0.1

to:

    Require ip 127.0.0.1 192.168.0

where you have to replace 192.168.0 to your corresponding IP-Adresses you want to gain access from. After one of the configuration steps below has also been performed, [re]start the Apache service.

#### Single-purpose Apache settings

Install mod_perlAUR.

Edit the Apache configuration file to load mod_perl, tell Apache to run as user backuppc and to include `/etc/httpd/conf/extra/backuppc.conf`:

    /etc/httpd/conf/httpd.conf

    LoadModule perl_module modules/mod_perl.so
    User backuppc
    Group backuppc
    Include conf/extra/backuppc.conf

#### Multi-purpose Apache settings

Instead of globally changing the Apache user and group like in the example above, we will instead make Apache run just the BackupPC CGI script as the backuppc user and leave the default user alone. This method uses mod_cgi to call a wrapper written in C instead of using the extra mod_perl dependency. You still need to have perl itself installed so the wrapper can run the BackupPC scripts.

Make sure Apache can run CGI programs (the line loading mod_cgi is not commented) and that it reads the BackupPC configuration by including it in `/etc/httpd/conf/extra/backuppc.conf`:

    /etc/httpd/conf/httpd.conf

    LoadModule cgi_module modules/mod_cgi.so
    Include conf/extra/backuppc.conf

##### The webserver user and the suid problem

The current setup of BackupPC, the webserver needs to run as backuppc user and this can be a problem on many setups where the webserver is used for other sites. In the past one could suid a Perl script, but it was blocked globally due security problems several years ago. To workaround that, perl-suid was used, but again blocked due the same problem more recently, scripts cannot be run securely with suid bit. Still there is another way, this time using a simple binary program that is suid as a launcher, that will run the backuppc Perl scripts already with the correct user. This isolates the Perl script from the environment and it is considered safe.

You need to replace the original backuppc CGI with the below C code compiled program and move the backuppc CGI to another place.

Move the real CGI `/usr/share/backuppc/cgi-bin/BackupPC_Admin` to the lib directory `/usr/share/backuppc/lib/real-BackupPC_Admin.cgi`.

Save the C code below to a file named wrapper.c (please update the CGI path if needed) and compile it with:

    $ gcc -o BackupPC_Admin wrapper.c

Note: If the compile fails with the error type of ‘ac’ defaults to ‘int’ , you can force gcc to use C89 standard with

    $ gcc -std=c89 -o BackupPC_Admin wrapper.c

The wrapper C code:

    #include <unistd.h>
    #define REAL_PATH "/usr/share/backuppc/lib/real-BackupPC_Admin.cgi"
    int main(ac, av)
    char **av;
    {
       execv(REAL_PATH, av);
       return 0;
    }

Place the new binary `BackupPC_Admin` in the cgi-bin directory and chown the binary CGI to `backuppc:http` and set the suid bit:

    # chown backuppc:http /usr/share/backuppc/cgi-bin/BackupPC_Admin
    # chmod 4750 /usr/share/backuppc/cgi-bin/BackupPC_Admin

Do not forget to clear the suid bit on the original Perl script if it was set (or the CGI page will not load):

    # chmod 0755 /usr/share/backuppc/lib/real-BackupPC_Admin.cgi

Keep your web server with its usual user and backup should now be able to run correctly.

Note: Keep in mind that the fix described in this section will be overwritten at every package upgrade, resulting in the BackupPC_Admin page displaying a message similar to Error: Wrong user: my userid is 33, instead of 126(backuppc). You will have to reapply the whole modification manually again to fix it.

## Alternative nginx configuration

Install nginx-mainline and fcgiwrap.

Create those two directories :

    # mkdir /etc/nginx/sites-available
    # mkdir /etc/nginx/sites-enabled

Edit nginx configuration file to include the configuration files from `sites-enabled`, by adding this at the end of the http block :

    /etc/nginx/nginx.conf

    http {
        ...
        include sites-enabled/*;
    }

    /etc/nginx/sites-available/backuppc

    server {
        listen <your_server_port>;
        server_name <your_server_name>;

        root  /usr/share/backuppc/html;
        index /index.cgi;

        access_log  /var/log/nginx/backuppc.access.log;
        error_log   /var/log/nginx/backuppc.error.log;

        location / {
            allow 127.0.0.1/32;
            # allow 192.168.0.0/24;
            deny all;

            # auth_basic "Backup";
            # auth_basic_user_file conf/backuppc.users;

            location /backuppc {
                alias /usr/share/backuppc/html;
            }

            location ~ \.cgi$ {
                include fastcgi_params;
                fastcgi_pass unix:/run/fcgiwrap.sock;

                fastcgi_param REMOTE_ADDR     $remote_addr;
                fastcgi_param REMOTE_USER     $remote_user;
                fastcgi_param SCRIPT_FILENAME /usr/share/backuppc/cgi-bin/BackupPC_Admin;
            }
        }
    }

And symlink to sites-enabled:

    # ln -s /etc/nginx/sites-available/backuppc /etc/nginx/sites-enabled

Edit the executing user in `fcgiwrap.service` file to `backuppc`.

Enable/start `nginx.service` and `fcgiwrap.socket`.

If you want to use basic authentication, uncomment the corresponding lines above and create the file `/etc/nginx/conf/backuppc.users` containing all allowed users :

    # echo -n 'myuser:' >> /etc/nginx/conf/backuppc.users
    # openssl passwd -apr1 >> /etc/nginx/conf/backuppc.users

Follow Certbot#Nginx to create a Let's Encrypt certificate and configure a TLS certificate.

## Alternative lighttpd configuration

    /etc/lighttpd/lighttpd.conf

     server.port             = 81
     server.username         = "backuppc"
     server.groupname        = "backuppc"
     server.document-root    = "/srv/http"
     server.errorlog         = "/var/log/lighttpd/error.log"
     dir-listing.activate    = "enable"
     index-file.names        = ( "index.html", "index.php", "index.cgi" )
     mimetype.assign         = ( ".html" => "text/html", ".txt" => "text/plain", ".jpg" => "image/jpeg", ".png" => "image/png", "" => "application/octet-stream" )

     server.modules = ("mod_alias", "mod_cgi", "mod_auth", "mod_access" )

     alias.url               = ( "/BackupPC_Admin" => "/usr/share/backuppc/cgi-bin/BackupPC_Admin" )
     alias.url               += ( "/backuppc" => "/usr/share/backuppc/html" )

     cgi.assign              += ( ".cgi" => "/usr/bin/perl" )
     cgi.assign              += ( "BackupPC_Admin" => "/usr/bin/perl" )

     auth.backend = "plain"
     auth.backend.plain.userfile = "/etc/lighttpd/passwd"
     auth.require = ( "/BackupPC_Admin" => ( "method" => "basic", "realm" => "BackupPC", "require" => "user=admin" ) )

    /etc/lighttpd/passwd

     admin:yourpassword

And create log file:

    # touch /var/log/lighttpd/error.log
    # chown backuppc:backuppc /var/log/lighttpd/error.log

## Accessing the admin page

Before accessing the admin page you have to specify which users/groups will be able to edit BackupPC's configuration.

    /etc/backuppc/config.pl

    $Conf{CgiAdminUserGroup} = '<authorized groups>';
    $Conf{CgiAdminUsers}     = '<authorized users>';  # <-- set to '*' if the webserver is not autenticating users

Browse to http://localhost/BackupPC_Admin respectively http://your_backuppc_server_ip/BackupPC_Admin.

## Website view problem

Due an Apache directive, the web interface may not shown properly. If that is your case, just modify the line in your `/etc/httpd/conf/httpd.conf` that avoids .htaccess and .htpasswd from viewed for clients or change directory name /usr/share/backuppc/html for /usr/share/backuppc/files and update `/etc/httpd/conf/extra/backuppc.conf` with the new path, as it follows:

    /etc/httpd/conf/extra/backuppc.conf

    Alias           /BackupPC/images        /usr/share/BackupPC/files/

## See also

- BackupPC Home page
- BackupPC documentation

Category:

- Backup