Netwatch (Host Monitoring)

Netwatch (Host Monitoring)

Version Info

RouterOS 7.16 | Min: v6.0+ | ⏱️ 10 minutes | 🟡 Intermediate

Tested on: 7.16 7.14

Version-specific notes

• v7.4+: Advanced probe types (icmp, tcp-conn, http-get, https-get, dns) with threshold configuration
• v7.0: VRF-qualified host addresses supported
• v6.x: Basic ICMP probe only (appears as type=simple after upgrade)

TL;DR (Quick Start)

For the impatient: monitor a host and run scripts on state change.

# Basic host monitoring
/tool/netwatch/add host=8.8.8.8 interval=30s comment="Google DNS"

# With failover scripts
/tool/netwatch/add host=8.8.8.8 interval=10s \
    down-script="/log warning \"Primary WAN down\"" \
    up-script="/log warning \"Primary WAN up\""

Verify with:

/tool/netwatch/print

Overview

What this does: Netwatch monitors network host availability using various probe types (ICMP, TCP, HTTP, DNS) and executes scripts when hosts go up or down. It’s essential for WAN failover, service health monitoring, and automated alerting.

When to use this:

• WAN failover detection and automatic route switching
• Service availability monitoring (web servers, DNS, etc.)
• Automated alerts via email or log when hosts fail
• Triggering configuration changes based on network conditions

Prerequisites:

• Network connectivity to monitored hosts
• Scripts must have appropriate permissions (read,write,test,reboot)
• For email alerts: /tool/e-mail configured

Probe Types

Type	Use Case	Version
simple	Basic ICMP ping (legacy)	6.x+
icmp	Advanced ping with thresholds	7.4+
tcp-conn	TCP port connectivity	7.4+
http-get	HTTP service check	7.4+
https-get	HTTPS with certificate validation	7.4+
dns	DNS server response	7.4+

Configuration Steps

Step 1: Create Basic Monitor

Monitor a host with simple ICMP:

/tool/netwatch/add host=8.8.8.8 interval=30s timeout=3s comment="Google DNS"

Step 2: Add Scripts for State Changes

Add scripts that run when the host goes down or comes back up:

/tool/netwatch/set [find host=8.8.8.8] \
    down-script="/log error \"Host 8.8.8.8 is DOWN\"" \
    up-script="/log info \"Host 8.8.8.8 is UP\""

Step 3: Verify Status

Check the current status:

/tool/netwatch/print

Expected output:

Flags: X - disabled
 #   HOST       TYPE    INTERVAL  TIMEOUT  STATUS  SINCE
 0   8.8.8.8    simple  30s       3s       up      jan/16/2026 10:00:00

Common Scenarios

Scenario: WAN Failover

Automatically switch routes when primary WAN fails:

Step 1: Configure routes with comments

/ip/route/add dst-address=0.0.0.0/0 gateway=192.168.1.1 distance=1 comment=primary
/ip/route/add dst-address=0.0.0.0/0 gateway=192.168.2.1 distance=2 comment=backup

Step 2: Create netwatch with failover scripts

/tool/netwatch/add host=8.8.8.8 interval=10s timeout=2s \
    down-script={
        /ip/route/set [find comment=primary] disabled=yes
        /log warning "Primary WAN down - switched to backup"
    } \
    up-script={
        /ip/route/set [find comment=primary] disabled=no
        /log warning "Primary WAN up - restored"
    }

Tip

For complex scripts, create named scripts in /system/script and call them:

down-script="/system/script/run wan-failover-down"

Scenario: Advanced ICMP with Thresholds (v7.4+)

Monitor with latency and packet loss thresholds:

/tool/netwatch/add host=10.0.0.1 type=icmp interval=30s \
    packet-count=5 \
    packet-interval=100ms \
    thr-avg=50ms \
    thr-max=200ms \
    thr-loss-percent=20 \
    down-script="/log error \"High latency or packet loss on link\""

The host is marked “down” if:

• Average latency exceeds 50ms
• Maximum latency exceeds 200ms
• Packet loss exceeds 20%

Scenario: HTTP Service Monitoring

Monitor a web server:

/tool/netwatch/add host=www.example.com type=http-get port=80 \
    interval=1m timeout=10s \
    http-code-min=200 http-code-max=299 \
    down-script="/log error \"Web server not responding\""

Scenario: HTTPS with Certificate Validation

Monitor HTTPS and validate the certificate:

/tool/netwatch/add host=secure.example.com type=https-get port=443 \
    check-certificate=yes \
    interval=5m \
    down-script="/log error \"HTTPS service or certificate issue\""

Scenario: DNS Server Monitoring

Monitor a DNS server’s ability to resolve queries:

/tool/netwatch/add host=example.com type=dns \
    dns-server=192.168.1.53 \
    record-type=A \
    interval=1m \
    down-script="/log error \"DNS server not responding\""

Scenario: Email Alerts

Send email when a host goes down:

Step 1: Configure email

/tool/e-mail/set server=smtp.example.com port=587 \
    start-tls=yes [email protected] password=secret

Step 2: Create netwatch with email scripts

/tool/netwatch/add host=192.168.1.100 interval=30s \
    down-script={
        /tool/e-mail/send [email protected] \
            subject="Server DOWN" \
            body="Host 192.168.1.100 is unreachable"
    } \
    up-script={
        /tool/e-mail/send [email protected] \
            subject="Server UP" \
            body="Host 192.168.1.100 recovered"
    }

Scenario: Internet Path Monitoring

Monitor internet connectivity without relying on a specific endpoint (using low TTL):

/tool/netwatch/add host=1.1.1.1 type=icmp \
    ttl=3 \
    accept-icmp-time-exceeded=yes \
    interval=15s \
    comment="Internet path check"

This marks “up” if any router along the path responds, even with “TTL exceeded.”

Scenario: Suppress Initial State Scripts

Prevent scripts from running when the router first boots:

/tool/netwatch/add host=8.8.8.8 interval=30s \
    ignore-initial-down=yes \
    startup-delay=5m \
    down-script="/log warning \"Host down\""

• ignore-initial-down=yes: Don’t run down-script for Unknown→Down transition
• startup-delay=5m: Wait 5 minutes after boot before monitoring

Scenario: TCP Port Check

Monitor if a specific TCP port is accepting connections:

/tool/netwatch/add host=192.168.1.50 type=tcp-conn port=3306 \
    interval=30s \
    down-script="/log error \"MySQL server not accepting connections\""

Verification

Confirm Netwatch is working correctly:

Check 1: View All Monitors

/tool/netwatch/print

Expected: Entries listed with status (up/down/unknown).

Check 2: View Detailed Status

/tool/netwatch/print detail

Shows all properties including scripts and thresholds.

Check 3: View Statistics

/tool/netwatch/print stats

Shows done-tests, failed-tests, and latency statistics.

Check 4: Filter by Status

/tool/netwatch/print where status=down

Shows only hosts that are currently unreachable.

Check 5: Check Script Execution in Logs

/log/print where topics~"script"

Look for script execution entries.

Troubleshooting

Symptom	Cause	Solution
Scripts not executing	Script policy exceeds allowed permissions	Set policy to read,write,test,reboot only
Down-script triggers at boot	Network not ready during startup	Increase startup-delay or use ignore-initial-down=yes
Monitoring doesn’t detect WAN failure	Monitoring target uses the failing link	Create static route for target via specific gateway
Status flapping rapidly	Interval too short or link unstable	Increase interval and packet-count
Inline script syntax errors	Quote escaping issues	Use named scripts instead of inline
Global variables not accessible	Netwatch runs as *sys user	Use environment variables or write to file
DNS probe fails unexpectedly	Uses /ip/dns settings	Set explicit dns-server property
HTTP fails on redirects	Default accepts only 2xx codes	Set http-code-max=399 to accept redirects

Debug: Test Script Manually

Create the script separately and test it:

/system/script/add name=test-script source="/log info \"Test\""
/system/script/run test-script

If it works, reference it in netwatch:

/tool/netwatch/set 0 down-script="/system/script/run test-script"

Debug: Check Script Permissions

Scripts must have limited permissions:

/system/script/print where name=myscript

Ensure policy shows only: read,write,test,reboot

Debug: Monitor Through Correct Interface

For WAN failover, ensure monitoring traffic uses the correct path:

# Force monitoring traffic through primary WAN
/ip/route/add dst-address=8.8.8.8/32 gateway=192.168.1.1 comment="monitor-route"

Common Mistakes

• Monitoring target through the link being monitored - If 8.8.8.8 is reached via primary WAN, and primary WAN fails, the monitor can’t reach 8.8.8.8 to detect the failure. Use a static route or monitor the gateway directly.
• Script permissions too broad - Netwatch can only run scripts with read,write,test,reboot policies. More permissions = script won’t run.
• Complex inline scripts - Quote escaping in inline scripts is error-prone. Use named scripts for anything complex.
• No startup delay - Scripts may trigger during boot before network is ready. Use startup-delay and ignore-initial-down.
• HTTP checking redirect URLs - Sites that redirect (301/302) fail with default settings. Adjust http-code-max or use final URL.

Community Tips

Named Scripts for Reliability: Instead of inline scripts with quote escaping issues, create named scripts:

/system/script/add name=wan-down policy=read,write,test,reboot source={
    /ip/route/set [find comment=primary] disabled=yes
    /log warning "Primary WAN failed"
}
/tool/netwatch/set 0 down-script="/system/script/run wan-down"

Monitor Gateway, Not Remote Host: For pure link monitoring, ping your ISP’s gateway instead of 8.8.8.8. This avoids routing complications.

LTE Failover: For LTE backup scenarios, monitor both WAN and LTE interfaces separately. Use route distances to control priority.

Test Before Production: Use /tool/netwatch/print stats to verify monitoring is working before relying on failover scripts.

Script Variables

Netwatch provides variables accessible in scripts:

Variable	Description
$"output"	Probe output/response
$"status"	Current status (up/down)
$"since"	Time of last status change

Example using variables:

down-script="/log warning (\"Host down since: \" . \$since)"

Related Topics

Action Scripts

• Scheduler - scripting fundamentals
• Email Tool - send alerts on state change
• Logging - log monitoring events

Failover Use Cases

• Static Routes - netwatch-triggered route changes
• VRRP - gateway failover
• Firewall Mangle - policy routing failover

Related Monitoring

• Torch - real-time traffic analysis
• Bandwidth Test - link capacity testing
• Ping Tool - basic connectivity testing

Reference

• MikroTik Netwatch Documentation

Key Commands Reference

Command	Description
/tool/netwatch/add	Create monitoring entry
/tool/netwatch/print	View all entries with status
/tool/netwatch/print stats	View performance statistics
/tool/netwatch/set	Modify existing entry
/tool/netwatch/remove	Delete monitoring entry

Core Properties

Property	Type	Default	Description
host	string	-	Target IP, domain, or VRF address (required)
type	enum	simple	Probe type: simple/icmp/tcp-conn/http-get/https-get/dns
interval	time	10s	Time between probes
timeout	time	3s	Maximum wait for response
src-address	IP	-	Source address for probes
startup-delay	time	5m	Delay after boot before monitoring
start-delay	time	3s	Delay before first probe

Script Properties

Property	Type	Description
up-script	string	Script on Down→Up transition
down-script	string	Script on Up→Down transition
test-script	string	Script after every probe
ignore-initial-up	yes/no	Suppress up-script for Unknown→Up
ignore-initial-down	yes/no	Suppress down-script for Unknown→Down

ICMP Probe Properties (v7.4+)

Property	Type	Default	Description
packet-count	integer	10	Packets per test
packet-interval	time	50ms	Delay between packets
packet-size	integer	54	Packet size in bytes
thr-avg	time	100ms	Average RTT threshold
thr-max	time	1s	Maximum RTT threshold
thr-loss-percent	percent	85%	Packet loss threshold
thr-jitter	time	1s	Jitter threshold

HTTP/HTTPS Properties (v7.4+)

Property	Type	Default	Description
port	integer	80/443	HTTP(S) port
http-code-min	integer	100	Minimum acceptable status code
http-code-max	integer	299	Maximum acceptable status code
check-certificate	yes/no	no	Validate SSL certificate
thr-http-time	time	10s	Response time threshold

Status Flags

Flag	Meaning
X	Disabled
status=up	Host reachable
status=down	Host unreachable
status=unknown	Not yet tested