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check_ssh.c

/*****************************************************************************
* 
* Nagios check_ssh plugin
* 
* License: GPL
* Copyright (c) 2000-2007 Nagios Plugins Development Team
* 
* Last Modified: $Date: 2008-05-07 11:02:42 +0100 (Wed, 07 May 2008) $
* 
* Description:
* 
* This file contains the check_ssh plugin
* 
* Try to connect to an SSH server at specified server and port
* 
* 
* This program 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 3 of the License, or
* (at your option) any later version.
* 
* This program 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 this program.  If not, see <http://www.gnu.org/licenses/>.
* 
* $Id: check_ssh.c 1991 2008-05-07 10:02:42Z dermoth $
* 
*****************************************************************************/

const char *progname = "check_ssh";
const char *revision = "$Revision: 1991 $";
const char *copyright = "2000-2007";
const char *email = "nagiosplug-devel@lists.sourceforge.net";

#include "common.h"
#include "netutils.h"
#include "utils.h"

#ifndef MSG_DONTWAIT
#define MSG_DONTWAIT 0
#endif

#define SSH_DFL_PORT    22
#define BUFF_SZ         256

int port = -1;
char *server_name = NULL;
char *remote_version = NULL;
int verbose = FALSE;

int process_arguments (int, char **);
int validate_arguments (void);
void print_help (void);
void print_usage (void);

int ssh_connect (char *haddr, int hport, char *remote_version);



int
main (int argc, char **argv)
{
      int result = STATE_UNKNOWN;

      setlocale (LC_ALL, "");
      bindtextdomain (PACKAGE, LOCALEDIR);
      textdomain (PACKAGE);

      /* Parse extra opts if any */
      argv=np_extra_opts (&argc, argv, progname);

      if (process_arguments (argc, argv) == ERROR)
            usage4 (_("Could not parse arguments"));

      /* initialize alarm signal handling */
      signal (SIGALRM, socket_timeout_alarm_handler);
      
      alarm (socket_timeout);

      /* ssh_connect exits if error is found */
      result = ssh_connect (server_name, port, remote_version);

      alarm (0);

      return (result);
}



/* process command-line arguments */
int
process_arguments (int argc, char **argv)
{
      int c;

      int option = 0;
      static struct option longopts[] = {
            {"help", no_argument, 0, 'h'},
            {"version", no_argument, 0, 'V'},
            {"host", required_argument, 0, 'H'},      /* backward compatibility */
            {"hostname", required_argument, 0, 'H'},
            {"port", required_argument, 0, 'p'},
            {"use-ipv4", no_argument, 0, '4'},
            {"use-ipv6", no_argument, 0, '6'},
            {"timeout", required_argument, 0, 't'},
            {"verbose", no_argument, 0, 'v'},
            {"remote-version", required_argument, 0, 'r'},
            {0, 0, 0, 0}
      };

      if (argc < 2)
            return ERROR;

      for (c = 1; c < argc; c++)
            if (strcmp ("-to", argv[c]) == 0)
                  strcpy (argv[c], "-t");

      while (1) {
            c = getopt_long (argc, argv, "+Vhv46t:r:H:p:", longopts, &option);

            if (c == -1 || c == EOF)
                  break;

            switch (c) {
            case '?':                                                   /* help */
                  usage5 ();
            case 'V':                                                   /* version */
                  print_revision (progname, revision);
                  exit (STATE_OK);
            case 'h':                                                   /* help */
                  print_help ();
                  exit (STATE_OK);
            case 'v':                                                   /* verbose */
                  verbose = TRUE;
                  break;
            case 't':                                                   /* timeout period */
                  if (!is_integer (optarg))
                        usage2 (_("Timeout interval must be a positive integer"), optarg);
                  else
                        socket_timeout = atoi (optarg);
                  break;
            case '4':
                  address_family = AF_INET;
                  break;
            case '6':
#ifdef USE_IPV6
                  address_family = AF_INET6;
#else
                  usage4 (_("IPv6 support not available"));
#endif
                  break;
            case 'r':                                                   /* remote version */
                  remote_version = optarg;
                  break;
            case 'H':                                                   /* host */
                  if (is_host (optarg) == FALSE)
                        usage2 (_("Invalid hostname/address"), optarg);
                  server_name = optarg;
                  break;
            case 'p':                                                   /* port */
                  if (is_intpos (optarg)) {
                        port = atoi (optarg);
                  }
                  else {
                        usage2 (_("Port number must be a positive integer"), optarg);
                  }
            }
      }

      c = optind;
      if (server_name == NULL && c < argc) {
            if (is_host (argv[c])) {
                  server_name = argv[c++];
            }
      }

      if (port == -1 && c < argc) {
            if (is_intpos (argv[c])) {
                  port = atoi (argv[c++]);
            }
            else {
                  print_usage ();
                  exit (STATE_UNKNOWN);
            }
      }

      return validate_arguments ();
}

int
validate_arguments (void)
{
      if (server_name == NULL)
            return ERROR;
      if (port == -1)                                             /* funky, but allows -p to override stray integer in args */
            port = SSH_DFL_PORT;
      return OK;
}


/************************************************************************
*
* Try to connect to SSH server at specified server and port
*
*-----------------------------------------------------------------------*/


int
ssh_connect (char *haddr, int hport, char *remote_version)
{
      int sd;
      int result;
      char *output = NULL;
      char *buffer = NULL;
      char *ssh_proto = NULL;
      char *ssh_server = NULL;
      char rev_no[20];

      sscanf ("$Revision: 1991 $", "$Revision: %[0123456789.]", rev_no);

      result = my_tcp_connect (haddr, hport, &sd);

      if (result != STATE_OK)
            return result;

      output = (char *) malloc (BUFF_SZ + 1);
      memset (output, 0, BUFF_SZ + 1);
      recv (sd, output, BUFF_SZ, 0);
      if (strncmp (output, "SSH", 3)) {
            printf (_("Server answer: %s"), output);
            close(sd);
            exit (STATE_CRITICAL);
      }
      else {
            strip (output);
            if (verbose)
                  printf ("%s\n", output);
            ssh_proto = output + 4;
            ssh_server = ssh_proto + strspn (ssh_proto, "-0123456789. ");
            ssh_proto[strspn (ssh_proto, "0123456789. ")] = 0;

            asprintf (&buffer, "SSH-%s-check_ssh_%s\r\n", ssh_proto, rev_no);
            send (sd, buffer, strlen (buffer), MSG_DONTWAIT);
            if (verbose)
                  printf ("%s\n", buffer);

            if (remote_version && strcmp(remote_version, ssh_server)) {
                  printf
                        (_("SSH WARNING - %s (protocol %s) version mismatch, expected '%s'\n"),
                         ssh_server, ssh_proto, remote_version);
                  close(sd);
                  exit (STATE_WARNING);
            }
            
            printf
                  (_("SSH OK - %s (protocol %s)\n"),
                   ssh_server, ssh_proto);
            close(sd);
            exit (STATE_OK);
      }
}



void
print_help (void)
{
      char *myport;
      asprintf (&myport, "%d", SSH_DFL_PORT);

      print_revision (progname, revision);

      printf ("Copyright (c) 1999 Remi Paulmier <remi@sinfomic.fr>\n");
      printf (COPYRIGHT, copyright, email);

      printf ("%s\n", _("Try to connect to an SSH server at specified server and port"));

  printf ("\n\n");

      print_usage ();

      printf (_(UT_HELP_VRSN));
      printf (_(UT_EXTRA_OPTS));

      printf (_(UT_HOST_PORT), 'p', myport);

      printf (_(UT_IPv46));

      printf (_(UT_TIMEOUT), DEFAULT_SOCKET_TIMEOUT);

      printf (" %s\n", "-r, --remote-version=STRING");
  printf ("    %s\n", _("Warn if string doesn't match expected server version (ex: OpenSSH_3.9p1)"));
      
      printf (_(UT_VERBOSE));

#ifdef NP_EXTRA_OPTS
      printf ("\n");
      printf ("%s\n", _("Notes:"));
      printf (_(UT_EXTRA_OPTS_NOTES));
#endif

      printf (_(UT_SUPPORT));
}



void
print_usage (void)
{
  printf (_("Usage:"));
      printf ("%s [-46] [-t <timeout>] [-r <remote version>] [-p <port>] <host>\n", progname);
}


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