# This file is part of Fail2Ban. # # Fail2Ban is free software; you can redistribute it and/or modify # it under the terms of the GNU General Public License as published by # the Free Software Foundation; either version 2 of the License, or # (at your option) any later version. # # Fail2Ban is distributed in the hope that it will be useful, # but WITHOUT ANY WARRANTY; without even the implied warranty of # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the # GNU General Public License for more details. # # You should have received a copy of the GNU General Public License # along with Fail2Ban; if not, write to the Free Software # Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA # Author: Cyril Jaquier # # $Revision: 1.2 $ __author__ = "Cyril Jaquier" __version__ = "$Revision: 1.2 $" __date__ = "$Date: 2005/11/20 17:07:47 $" __copyright__ = "Copyright (c) 2004 Cyril Jaquier" __license__ = "GPL" import os, logging, signal # Gets the instance of the logger. logSys = logging.getLogger("fail2ban") class ExternalError(UserWarning): """ Exception to warn about failed fwcheck or fwban command """ pass def createDaemon(): """ Detach a process from the controlling terminal and run it in the background as a daemon. http://aspn.activestate.com/ASPN/Cookbook/Python/Recipe/278731 """ try: # Fork a child process so the parent can exit. This will return control # to the command line or shell. This is required so that the new process # is guaranteed not to be a process group leader. We have this guarantee # because the process GID of the parent is inherited by the child, but # the child gets a new PID, making it impossible for its PID to equal its # PGID. pid = os.fork() except OSError, e: return((e.errno, e.strerror)) # ERROR (return a tuple) if (pid == 0): # The first child. # Next we call os.setsid() to become the session leader of this new # session. The process also becomes the process group leader of the # new process group. Since a controlling terminal is associated with a # session, and this new session has not yet acquired a controlling # terminal our process now has no controlling terminal. This shouldn't # fail, since we're guaranteed that the child is not a process group # leader. os.setsid() # When the first child terminates, all processes in the second child # are sent a SIGHUP, so it's ignored. signal.signal(signal.SIGHUP, signal.SIG_IGN) try: # Fork a second child to prevent zombies. Since the first child is # a session leader without a controlling terminal, it's possible for # it to acquire one by opening a terminal in the future. This second # fork guarantees that the child is no longer a session leader, thus # preventing the daemon from ever acquiring a controlling terminal. pid = os.fork() # Fork a second child. except OSError, e: return((e.errno, e.strerror)) # ERROR (return a tuple) if (pid == 0): # The second child. # Ensure that the daemon doesn't keep any directory in use. Failure # to do this could make a filesystem unmountable. os.chdir("/") else: os._exit(0) # Exit parent (the first child) of the second child. else: os._exit(0) # Exit parent of the first child. # Close all open files. Try the system configuration variable, SC_OPEN_MAX, # for the maximum number of open files to close. If it doesn't exist, use # the default value (configurable). try: maxfd = os.sysconf("SC_OPEN_MAX") except (AttributeError, ValueError): maxfd = 256 # default maximum for fd in range(0, maxfd): try: os.close(fd) except OSError: # ERROR (ignore) pass # Redirect the standard file descriptors to /dev/null. os.open("/dev/null", os.O_RDONLY) # standard input (0) os.open("/dev/null", os.O_RDWR) # standard output (1) os.open("/dev/null", os.O_RDWR) # standard error (2) return True def killPID(pid): """ Kills the process with the given PID using the INT signal (same effect as +). """ try: return os.kill(pid, 2) except OSError: logSys.error("Can not kill process " + `pid` + ". Please check that " + "Fail2Ban is not running and remove the file " + "'/tmp/fail2ban.pid'") return False def executeCmd(cmd, debug): """ Executes an OS command. """ if cmd == "": logSys.debug("Nothing to do") return None logSys.debug(cmd) if not debug: retval = os.system(cmd) if not retval == 0: logSys.error("'" + cmd + "' returned " + `retval`) raise ExternalError("Execution of command '%s' failed" % cmd) return retval else: return None