4 files changed, 62 insertions, 17 deletions

diff --git a/plugins-root/check_dhcp.c b/plugins-root/check_dhcp.c
index 0ddace5..5ba9372 100644
--- a/plugins-root/check_dhcp.c
+++ b/plugins-root/check_dhcp.c
@@ -150,6 +150,7 @@ typedef struct dhcp_offer_struct{
         uint32_t lease_time;            /* lease time in seconds */
         uint32_t renewal_time;          /* renewal time in seconds */
         uint32_t rebinding_time;        /* rebinding time in seconds */
+        bool desired;                 /* is this offer desired (necessary in exclusive mode) */
         struct dhcp_offer_struct *next;
 }dhcp_offer;
 
@@ -192,7 +193,8 @@ typedef struct requested_server_struct{
 #define ETHERNET_HARDWARE_ADDRESS            1     /* used in htype field of dhcp packet */
 #define ETHERNET_HARDWARE_ADDRESS_LENGTH     6     /* length of Ethernet hardware addresses */
 
-uint8_t unicast = 0;        /* unicast mode: mimic a DHCP relay */
+bool unicast = false;        /* unicast mode: mimic a DHCP relay */
+bool exclusive = false;      /* exclusive mode aka "rogue DHCP server detection" */
 struct in_addr my_ip;        /* our address (required for relay) */
 struct in_addr dhcp_ip;      /* server to query (if in unicast mode) */
 unsigned char client_hardware_address[MAX_DHCP_CHADDR_LENGTH]="";
@@ -894,6 +896,7 @@ int add_dhcp_offer(struct in_addr source,dhcp_packet *offer_packet){
         new_offer->lease_time=dhcp_lease_time;
         new_offer->renewal_time=dhcp_renewal_time;
         new_offer->rebinding_time=dhcp_rebinding_time;
+        new_offer->desired=false; /* exclusive mode: we'll check that in get_results */
 
 
         if(verbose){
@@ -939,7 +942,7 @@ int free_requested_server_list(void){
 
 /* gets state and plugin output to return */
 int get_results(void){
-        dhcp_offer *temp_offer;
+        dhcp_offer *temp_offer, *undesired_offer=NULL;
         requested_server *temp_server;
         int result;
         uint32_t max_lease_time=0;
@@ -974,11 +977,19 @@ int get_results(void){
                                         if(!temp_server->answered){
                                                 requested_responses++;
                                                 temp_server->answered=true;
+                                                temp_offer->desired=true;
                                         }
                                 }
                         }
                 }
 
+                /* exclusive mode: check for undesired offers */
+                for(temp_offer=dhcp_offer_list;temp_offer!=NULL;temp_offer=temp_offer->next) {
+                        if (!temp_offer->desired) {
+                                undesired_offer=temp_offer; /* Checks only for the first undesired offer */
+                                break; /* no further checks needed */
+                        }
+                }
         }
 
         /* else check and see if we got our requested address from any server */
@@ -1006,6 +1017,9 @@ int get_results(void){
         else if(request_specific_address && !received_requested_address)
                 result=STATE_WARNING;
 
+        if(exclusive && undesired_offer)
+                result=STATE_CRITICAL;
+
         if(result==0)               /* garrett honeycutt 2005 */
                 printf("OK: ");
         else if(result==1)
@@ -1023,6 +1037,13 @@ int get_results(void){
 
         printf(_("Received %d DHCPOFFER(s)"),valid_responses);
 
+
+        if(exclusive && undesired_offer){
+                printf(_(", Rogue DHCP Server detected! Server %s"),inet_ntoa(undesired_offer->server_address));
+                printf(_(" offered %s \n"),inet_ntoa(undesired_offer->offered_address));
+                return result;
+        }
+
         if(requested_servers>0)
                 printf(_(", %s%d of %d requested servers responded"),((requested_responses<requested_servers) && requested_responses>0)?"only ":"",requested_responses,requested_servers);
 
@@ -1065,16 +1086,16 @@ int call_getopt(int argc, char **argv){
                 {"interface",      required_argument,0,'i'},
                 {"mac",            required_argument,0,'m'},
                 {"unicast",        no_argument,      0,'u'},
+                {"exclusive",      no_argument,      0,'x'},
                 {"verbose",        no_argument,      0,'v'},
                 {"version",        no_argument,      0,'V'},
                 {"help",           no_argument,      0,'h'},
                 {0,0,0,0}
         };
 
-        while(1){
-                int c=0;
-
-                c=getopt_long(argc,argv,"+hVvt:s:r:t:i:m:u",long_options,&option_index);
+        int c=0;
+        while(true){
+                c=getopt_long(argc,argv,"+hVvxt:s:r:t:i:m:u",long_options,&option_index);
 
                 if(c==-1||c==EOF||c==1)
                         break;
@@ -1121,7 +1142,10 @@ int call_getopt(int argc, char **argv){
                                 break;
 
                         case 'u': /* unicast testing */
-                                unicast=1;
+                                unicast=true;
+                                break;
+                        case 'x': /* exclusive testing aka "rogue DHCP server detection" */
+                                exclusive=true;
                                 break;
 
                         case 'V': /* version */
@@ -1135,7 +1159,6 @@ int call_getopt(int argc, char **argv){
                         case 'v': /* verbose */
                                 verbose=1;
                                 break;
-
                         case '?': /* help */
                                 usage5 ();
                                 break;
@@ -1372,6 +1395,8 @@ void print_help(void){
         printf ("    %s\n", _("MAC address to use in the DHCP request"));
         printf (" %s\n", "-u, --unicast");
         printf ("    %s\n", _("Unicast testing: mimic a DHCP relay, requires -s"));
+        printf (" %s\n", "-x, --exclusive");
+        printf ("    %s\n", _("Only requested DHCP server may response (rogue DHCP server detection), requires -s"));
 
         printf (UT_SUPPORT);
         return;
@@ -1382,7 +1407,7 @@ void
 print_usage(void){
 
         printf ("%s\n", _("Usage:"));
-        printf (" %s [-v] [-u] [-s serverip] [-r requestedip] [-t timeout]\n",progname);
+        printf (" %s [-v] [-u] [-x] [-s serverip] [-r requestedip] [-t timeout]\n",progname);
         printf ("                  [-i interface] [-m mac]\n");
 
         return;
diff --git a/po/de.po b/po/de.po
index 6d79f9d..1b666f4 100644
--- a/po/de.po
+++ b/po/de.po
@@ -9,7 +9,7 @@ msgid ""
 msgstr ""
 "Project-Id-Version: PACKAGE VERSION\n"
 "Report-Msgid-Bugs-To: devel@monitoring-plugins.org\n"
-"POT-Creation-Date: 2023-10-01 00:46+0200\n"
+"POT-Creation-Date: 2023-10-01 15:10+0200\n"
 "PO-Revision-Date: 2004-12-23 17:46+0100\n"
 "Last-Translator:  \n"
 "Language-Team: Monitoring Plugin Development Team <devel@monitoring-plugins."
@@ -4989,6 +4989,14 @@ msgid "Received %d DHCPOFFER(s)"
 msgstr ""
 
 #, c-format
+msgid ", Rogue DHCP Server detected! Server %s"
+msgstr ""
+
+#, c-format
+msgid " offered %s \n"
+msgstr ""
+
+#, c-format
 msgid ", %s%d of %d requested servers responded"
 msgstr ""
 
@@ -5056,6 +5064,11 @@ msgstr ""
 msgid "Unicast testing: mimic a DHCP relay, requires -s"
 msgstr ""
 
+msgid ""
+"Only requested DHCP server may response (rogue DHCP server detection), "
+"requires -s"
+msgstr ""
+
 msgid "specify a target"
 msgstr ""
 
diff --git a/po/fr.po b/po/fr.po
index c59042d..a85945a 100644
--- a/po/fr.po
+++ b/po/fr.po
@@ -5210,9 +5210,6 @@ msgstr ", %s%d de %d serveurs ont répondus"
 msgid ", requested address (%s) was %soffered"
 msgstr ", l'adresse demandée (%s) %s été offerte"
 
-msgid "not "
-msgstr "n'as pas"
-
 #, c-format
 msgid ", max lease time = "
 msgstr ", bail maximum = "
@@ -5221,9 +5218,6 @@ msgstr ", bail maximum = "
 msgid "Infinity"
 msgstr "Infini"
 
-msgid "Got unexpected non-option argument"
-msgstr ""
-
 #, c-format
 msgid "Error: DLPI stream API failed to get MAC in check_ctrl: %s.\n"
 msgstr ""
diff --git a/po/monitoring-plugins.pot b/po/monitoring-plugins.pot
index 90424b7..6b63fd9 100644
--- a/po/monitoring-plugins.pot
+++ b/po/monitoring-plugins.pot
@@ -8,7 +8,7 @@ msgid ""
 msgstr ""
 "Project-Id-Version: PACKAGE VERSION\n"
 "Report-Msgid-Bugs-To: devel@monitoring-plugins.org\n"
-"POT-Creation-Date: 2023-10-01 00:46+0200\n"
+"POT-Creation-Date: 2023-10-01 15:10+0200\n"
 "PO-Revision-Date: YEAR-MO-DA HO:MI+ZONE\n"
 "Last-Translator: FULL NAME <EMAIL@ADDRESS>\n"
 "Language-Team: LANGUAGE <LL@li.org>\n"
@@ -4816,6 +4816,14 @@ msgid "Received %d DHCPOFFER(s)"
 msgstr ""
 
 #, c-format
+msgid ", Rogue DHCP Server detected! Server %s"
+msgstr ""
+
+#, c-format
+msgid " offered %s \n"
+msgstr ""
+
+#, c-format
 msgid ", %s%d of %d requested servers responded"
 msgstr ""
 
@@ -4883,6 +4891,11 @@ msgstr ""
 msgid "Unicast testing: mimic a DHCP relay, requires -s"
 msgstr ""
 
+msgid ""
+"Only requested DHCP server may response (rogue DHCP server detection), "
+"requires -s"
+msgstr ""
+
 msgid "specify a target"
 msgstr ""