check_snmp: use snmp v2c if community is given

1 files changed, 8 insertions, 0 deletions

diff --git a/plugins/check_snmp.c b/plugins/check_snmp.c
index 7851631c..35e1f339 100644
--- a/plugins/check_snmp.c
+++ b/plugins/check_snmp.c
@@ -516,6 +516,7 @@ static process_arguments_wrapper process_arguments(int argc, char **argv) {
         char *port = NULL;
         char *miblist = NULL;
         char *connection_prefix = NULL;
+        bool snmp_version_set_explicitely = false;
         // TODO error checking
         while (true) {
                 int option_char = getopt_long(
@@ -567,6 +568,8 @@ static process_arguments_wrapper process_arguments(int argc, char **argv) {
                         } else {
                                 die(STATE_UNKNOWN, "invalid SNMP version/protocol: %s", optarg);
                         }
+                        snmp_version_set_explicitely = true;
+
                         break;
                 case 'N': /* SNMPv3 context name */
                         config.snmp_session.contextName = optarg;
@@ -858,6 +861,11 @@ static process_arguments_wrapper process_arguments(int argc, char **argv) {
                 setenv("MIBS", miblist, 1);
         }
 
+        // Historical default is SNMP v2c
+        if (!snmp_version_set_explicitely && config.snmp_session.community != NULL) {
+                config.snmp_session.version = SNMP_VERSION_2c;
+        }
+
         if ((config.snmp_session.version == SNMP_VERSION_1) ||
                 (config.snmp_session.version == SNMP_VERSION_2c)) {     /* snmpv1 or snmpv2c */
                                                                                                                                 /*