NAME

backup - FTP system archiving utility

backup

backup allows one to archive selected directories of the system to a remote location via the FTP protocol.  This is a simple utility and has not been tested for security holes, so be forewarned.  The design of the utility took into consideration as many factors as time allowed and as were known at the time.  Specific security risks will be noted as appropriate in the document.

backup must be run by root, and not as a setuid program.  backup begins by reading a configuration file, /etc/backup.conf, which can be configured in the source code.  This file must have the proper permissions to be acceptable to backup as a configuration file:
 

• must be owned by root
• must be readable by root
• must be unwritable by anyone other than root
 
backup does not check to see if the file is readable by others besides root, which is a definite security compromise of the target FTP account, as the account name and account password are stored here.  Future incarnations will encrypt this information.  See CONFIGURATION for the format of /etc/backup.conf.

backup then tars the specified subdirectories and compresses the resulting file using GNU's gzip.  This file is stored by default in /tmp.  backup logs into the FTP site and transfers  the file to the remote directory /backup in the FTP account's top level directory.  This directory must exist and have appropriate permissions for the account holder to cd and write to the directory prior to the archive procedure or backup will fail.  Once the file is transferred, backup prints a summary of the number of bytes transferred and the effective data transfer speed, deletes the local archive file, and exits.
 

/etc/backup.conf is similar to most standard configuration files.  Lines beginning with a # and blank lines are ignored.  A valid line consists of a keyword followed immediately by an equals sign and the value of the resouce.  Only four keywords are recognized: others are ignored also:
 
• DIR:      pathname of a top level directory subtree to archive
• FTP:      FTP site internet address (name or numeric format)
• USER:  FTP account username
• PASS:   FTP account password
/etc/backup.conf SHOULD NOT BE READABLE BY ANYONE BUT ROOT!!  Passwords should never be stored in plaintext anyway; this will be fixed later.

the DIR keyword can appear multiple times in the configuration file.  The remaining keywords must only be specified once.  If any of these appears more than once, only the first specification is valid.  If any of the FTP keywords is absent, backup fails (future versions should default to anonymous FTP when USER and PASS are not specified).

Example:
 

# WARNING... to protect your account, this backup.conf file
# should be only readable by root.
DIR=/usr/home
DIR=/etc
DIR=/var
DIR=/usr/X11R6/etc
FTP=ftp.the.white.house.gov
USER=bclinton
PASS=I_Love_Hillary!!

backup does not implement a very robust security model.  A few points which need to be addressed are:
• /etc/backup.conf needs to use encrypted entries
• the archive file needs to be encrypted
If a specified subdirectory to be archived contains a sybolic link to a non-existent file, backup fails in the tar operation.