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Revision as of 17:30, 25 May 2013 by Opt1mus (talk | contribs) (The webserver user and the suid problem: spurious extra space removed, and ic)
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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.


Install backuppc from the official repositories. Install rsync and perl-file-rsyncp if you want to use rsync as a transport.

Start BackupPC

To manually start BackupPC issue this command:

# systemctl start backuppc

To make BackupPC load at startup:

# systemctl enable backuppc

Apache Configuration

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

Edit Apache configuration

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:

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

Edit /etc/backuppc/ 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, 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

allow from


allow from 192.168.0

where you have to replace 192.168.0 to your corresponding IP-Adresses you want to gain access from. Then just start Apache service.

Alternative lighttpd Configuration

 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" ) )


Accessing the admin page

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

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 can't 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 enviorment and its considered safe.

To setup the backuppc to run on this mode you need to replace the original backuppc cgi with the below C code compiled program and move the backuppc cgi to another place.

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

gcc -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;

move the real cgi /usr/share/backuppc/cgi-bin/BackupPC_Admin to the lib directory /usr/share/backuppc/lib/real-BackupPC_Admin.cgi , 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.

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