Linux Security Cookbook [Electronic resources] نسخه متنی

Trying the Recipes

Most recipes provide commands or scripts
you can run, or a set of configuration options for a particular
program. When trying a recipe, please keep in mind:

• Our default shell for recipes is
  
  bash.
  If you use another shell, you might need different syntax for setting
  environment variables and other shell-specific things.




• If you create a Linux shell script (say,
  "myscript") in your current
  directory, but the current directory
  (".") is not in your search path,
  you can't run it simply by typing the script name:

  $ myscript
  bash: myscript: command not found

  because the shell won't find it. To invoke the
  script, specify that it's in the current directory:

  $ ./myscript

  Alternatively, you could add the current directory to your search
  path, but we recommend against this. [Recipe 9.7]




• Linux commands may behave differently when run in an interactive
  shell, a script, or a batch job (e.g., via cron).
  Each method may have a different environment (for example, search
  path), and some commands even are coded to behave differently
  depending how they are invoked. If a recipe does not behave as you
  expect in a script, try running it interactively, and vice versa. You
  can see your environment with the env command, and
  your shell variables with the set built-in
  command.




• Different Linux distributions may place
  important binaries and configuration files in locations different
  from those in our recipes. Programs are assumed to be in your search
  path. You might need to add directories to your path, such as
  /sbin, /usr/sbin, and
  /usr/kerberos/bin. If you cannot find a file,
  try the locate command:^[1]

  ^[1] Contained
  in the RPM package slocate (for Red Hat) or
  findutils-locate (for SuSE).

  $ locate sshd.config
  /etc/ssh/sshd_config

  or in the worst case, the find command from the
  root of the filesystem, as root:

  # find / -name sshd_config -print




• Make sure you have the most recent versions of programs involved in
  the recipe, or at least stable versions, and that the programs are
  properly installed.

Finally, each Linux system is unique. While we have tested these
recipes on various machines, yours might be different enough to
produce unexpected results.

Before you run any recipe, make sure you understand how it will affect security on your system.