feat: Add SNMP Monitor

db/knex_migrations/2024-04-26-0000-snmp-monitor.js

@@ -0,0 +1,14 @@
+exports.up = function (knex) {
+    return knex.schema
+        .alterTable("monitor", function (table) {
+            table.string("snmp_community_string", 255).defaultTo("public"); // Add snmp_community_string column
+            table.string("snmp_oid").defaultTo(null); // Add oid column
+            table.enum("snmp_version", ["1", "2c", "3"]).defaultTo("2c"); // Add snmp_version column with enum values
+            table.float("snmp_control_value").defaultTo(null); // Add control_value column as float
+            table.string("snmp_condition").defaultTo(null); // Add oid column
+        });
+};
+
+exports.down = function (knex) {
+    // Nothing to do here
+};

package.json

@@ -119,6 +119,7 @@
         "mssql": "~8.1.4",
         "mysql2": "~3.9.6",
         "nanoid": "~3.3.4",
+        "net-snmp": "^3.11.2",
         "node-cloudflared-tunnel": "~1.0.9",
         "node-radius-client": "~1.0.0",
         "nodemailer": "~6.9.13",

server/model/monitor.js

@@ -161,6 +161,10 @@ class Monitor extends BeanModel {
             kafkaProducerMessage: this.kafkaProducerMessage,
             screenshot,
             remote_browser: this.remote_browser,
+            snmpOid: this.snmpOid,
+            snmpCondition: this.snmpCondition,
+            snmpControlValue: this.snmpControlValue,
+            snmpVersion: this.snmpVersion,
         };
 
         if (includeSensitiveData) {
@@ -190,6 +194,7 @@ class Monitor extends BeanModel {
                 tlsCert: this.tlsCert,
                 tlsKey: this.tlsKey,
                 kafkaProducerSaslOptions: JSON.parse(this.kafkaProducerSaslOptions),
+                snmpCommunityString: this.snmpCommunityString,
             };
         }
 

server/monitor-types/snmp.js

@@ -0,0 +1,107 @@
+const { MonitorType } = require("./monitor-type");
+const { UP, DOWN, log } = require("../../src/util");
+const snmp = require("net-snmp");
+
+class SNMPMonitorType extends MonitorType {
+    name = "snmp";
+
+    /**
+     * Checks the SNMP value against the condition and control value.
+     * @param {object} monitor The monitor object associated with the check.
+     * @param {object} heartbeat The heartbeat object to update.
+     * @param {object} _server Unused server object.
+     */
+    async check(monitor, heartbeat, _server) {
+
+        log.debug("monitor", `SNMP: Community String: ${monitor.snmpCommunityString}`);
+        log.debug("monitor", `SNMP: OID: ${monitor.snmpOid}`);
+        log.debug("monitor", `SNMP: Version: ${monitor.snmpVersion}`);
+        log.debug("monitor", `SNMP: Condition: ${monitor.snmpCondition}`);
+        log.debug("monitor", `SNMP: Control Value: ${monitor.snmpControlValue}`);
+
+        const options = {
+            port: monitor.port || '161',
+            retries: monitor.maxretries,
+            timeout: 1000,
+            version: getKey(snmp.Version, monitor.snmpVersion) || snmp.Version2c,
+        };
+
+        function getKey(obj, value) {
+            return Object.keys(obj).find(key => obj[key] === value) || null;
+        }
+
+        try {
+            const session = snmp.createSession(monitor.hostname, monitor.snmpCommunityString, options);
+
+            // Handle errors during session creation
+            session.on('error', (error) => {
+                heartbeat.status = DOWN;
+                heartbeat.msg = `SNMP: Error creating SNMP session: ${error.message}`;
+                log.debug("monitor", `SNMP: ${heartbeat.msg}`);
+            });
+
+            const varbinds = await new Promise((resolve, reject) => {
+                session.get([monitor.snmpOid], (error, varbinds) => {
+                    if (error) {
+                        reject(error);
+                    } else {
+                        log.debug("monitor", `SNMP: Received varbinds: Type: ${getKey(snmp.ObjectType, varbinds[0].type)}, Value: ${varbinds[0].value}`); // Log the received varbinds for debugging
+                        resolve(varbinds);
+                    }
+                });
+            });
+
+            if (varbinds.length === 0 || getKey(snmp.ObjectType, varbinds[0].type) === 'NoSuchInstance') {
+                throw new Error(`No varbinds returned from SNMP session (OID: ${monitor.snmpOid})`);
+            } else {
+                const value = varbinds[0].value;
+                const numericValue = parseInt(value);
+                const stringValue = value.toString('ascii');
+
+                switch (monitor.snmpCondition) {
+                    case '>':
+                        heartbeat.status = numericValue > monitor.snmpControlValue ? UP : DOWN;
+                        break;
+                    case '>=':
+                        heartbeat.status = numericValue >= monitor.snmpControlValue ? UP : DOWN;
+                        break;
+                    case '<':
+                        heartbeat.status = numericValue < monitor.snmpControlValue ? UP : DOWN;
+                        break;
+                    case '<=':
+                        heartbeat.status = numericValue <= monitor.snmpControlValue ? UP : DOWN;
+                        break;
+                    case '==':
+                        if (!isNaN(value) && !isNaN(monitor.snmpControlValue)) {
+                            // Both values are numeric, parse them as numbers
+                            heartbeat.status = parseFloat(value) === parseFloat(monitor.snmpControlValue) ? UP : DOWN;
+                        } else {
+                            // At least one of the values is not numeric, compare them as strings
+                            heartbeat.status = value.toString() === monitor.snmpControlValue.toString() ? UP : DOWN;
+                        }
+                        break;
+                    case 'contains':
+                        heartbeat.status = stringValue.includes(monitor.snmpControlValue) ? UP : DOWN;
+                        break;
+                    default:
+                        heartbeat.status = DOWN;
+                        heartbeat.msg = `Invalid condition: ${monitor.snmpCondition}`;
+                        break;
+                }
+                heartbeat.msg = `SNMP value ` + (heartbeat.status ? `passes` : `does not pass`) + ` comparison: ${value.toString('ascii')} ${monitor.snmpCondition} ${monitor.snmpControlValue}`;
+
+            }
+            session.close(); // Close the session after use
+
+        } catch (err) {
+            heartbeat.status = DOWN;
+            heartbeat.msg = `SNMP Error: ${err.message}`;
+            log.debug("monitor", `SNMP: ${heartbeat.msg}`);
+        }
+    }
+
+}
+
+module.exports = {
+    SNMPMonitorType,
+};

server/server.js

@@ -830,6 +830,11 @@ let needSetup = false;
                     monitor.kafkaProducerAllowAutoTopicCreation;
                 bean.gamedigGivenPortOnly = monitor.gamedigGivenPortOnly;
                 bean.remote_browser = monitor.remote_browser;
+                bean.snmpVersion = monitor.snmpVersion;
+                bean.snmpCommunityString = monitor.snmpCommunityString;
+                bean.snmpOid = monitor.snmpOid;
+                bean.snmpCondition = monitor.snmpCondition;
+                bean.snmpControlValue = monitor.snmpControlValue;
 
                 bean.validate();
 

server/uptime-kuma-server.js

@@ -113,6 +113,7 @@ class UptimeKumaServer {
         UptimeKumaServer.monitorTypeList["tailscale-ping"] = new TailscalePing();
         UptimeKumaServer.monitorTypeList["dns"] = new DnsMonitorType();
         UptimeKumaServer.monitorTypeList["mqtt"] = new MqttMonitorType();
+        UptimeKumaServer.monitorTypeList["snmp"] = new SNMPMonitorType();
 
         // Allow all CORS origins (polling) in development
         let cors = undefined;
@@ -516,3 +517,4 @@ const { RealBrowserMonitorType } = require("./monitor-types/real-browser-monitor
 const { TailscalePing } = require("./monitor-types/tailscale-ping");
 const { DnsMonitorType } = require("./monitor-types/dns");
 const { MqttMonitorType } = require("./monitor-types/mqtt");
+const { SNMPMonitorType } = require("./monitor-types/snmp");