Misc · Topic 1 of 3
RouterOS Tools, E-mail, Netwatch, Ping, Traceroute and Profiler
Use the RouterOS tools menu for troubleshooting and alerts: e-mail, Netwatch host monitoring, ping, traceroute and the profiler that shows CPU load.
- 5 min
- Ping tests reachability, and
src-addresschooses the source. - Traceroute lists the routers on the path to a destination.
- Netwatch checks a host at an interval and runs a script when it goes up or down.
What it is
The tools menu holds the utilities that you use to test a network and to react when something changes.
Ping and traceroute test reachability and show the path. Netwatch watches hosts and runs a script when one goes up or down.
E-mail lets the router send messages, so it can report events. The profiler shows which parts of the system use the CPU.
How it works
Each tool answers one question, and together they cover testing, alerting and load.
Ping
Ping sends ICMP echo requests and measures the replies.
/ping 8.8.8.8 count=4
/ping 192.168.2.10 src-address=192.168.1.1 size=1400Useful options include count for the number of packets, size for the packet size and src-address to choose the source. The source address matters on a router with several addresses, because the reply must find its way back to that address.
A reply shows the round trip time. A timeout means the packet or its reply was lost. The packet size option, together with a do-not-fragment option, can reveal an MTU problem on a path.
Traceroute
Traceroute shows each router on the path to a destination.
/tool traceroute 8.8.8.8It sends packets with a growing time to live, and each router that discards one reveals itself. The output lists the hops in order, with the delay to each. Where the list stops or shows timeouts is usually where the problem lies.
A hop that does not answer is not always a fault. Some routers choose not to reply, but still forward traffic.
Use ping to find out whether a destination answers, and traceroute to find out where the path breaks.
Netwatch
Netwatch checks hosts at regular intervals, and it runs scripts when the state changes.
/tool netwatch add host=203.0.113.1 interval=30s timeout=1s up-script="" down-script=""
/tool netwatch printThe host is the address to watch. The interval is how often to check, and the timeout is how long to wait for a reply. The down-script runs when the host stops answering, and the up-script runs when it returns.
The status of each entry is up or down, with the time of the last change. Newer versions add other kinds of probe besides ping, so check the options of your version.
A common use is to switch to a backup link. The down script disables a route or an interface, and the up script restores it. Another use is to send a message to the administrator, using the e-mail tool.
The e-mail tool lets the router send mail through an SMTP server.
/tool e-mail print
/tool e-mail send to=admin@example.com subject="Link down" body="The WAN host is not answering"Before it can send, the tool needs the address of the mail server and a sender address. The name of the server setting differs between RouterOS versions, so type the command followed by a question mark to see it in your version.
The e-mail tool is the delivery method for alerts. A Netwatch script can call it when a host goes down, and a watchdog or log action can use it too.
Profiler
The profiler measures what uses the CPU of the router.
/tool profile
/system resource printThe profile tool lists processes with their share of the CPU, such as firewall, networking and the wireless handling. Run it when the CPU is busy, and the process at the top shows what is responsible. The resource print command shows the overall CPU load and the memory.
If the firewall dominates, look at the number of rules and at FastTrack. If a service dominates, look at what that service is doing.
A high CPU is a symptom and not a cause, so use the profiler to find which process creates the load before you change anything.
Choosing the right tool
| Question | Tool |
|---|---|
| Does the host answer? | Ping |
| Where does the path stop? | Traceroute |
| Tell me when a host changes state | Netwatch |
| Send me a message | |
| Why is the CPU busy? | Profiler |
What to remember for the exam
Seven facts cover this topic.
- Ping tests reachability, and
src-addresschooses the source. - Traceroute lists the routers on the path to a destination.
- Netwatch checks a host at an interval and runs a script when it goes up or down.
- Netwatch uses
host,interval,timeout,up-scriptanddown-script. - The e-mail tool needs a mail server address and a sender before it can send.
/tool e-mail sendsends a message, and Netwatch can trigger it.- The profiler shows which processes use the CPU.
Common mistakes
These four mistakes are common.
Pinging from the wrong source. The reply returns to a different address and the test fails, so choose the source.
Treating silent hops as faults. A traceroute hop that does not reply may still forward traffic.
Setting a tiny Netwatch interval. Frequent checks add load and can flap on a single lost packet.
Sending e-mail without server settings. The message is never sent.
Check yourself
Work through these three questions.
What does Netwatch do when a host stops answering?
It marks the host as down and runs the
down-script. When the host answers again, it runs theup-script.What is the difference between ping and traceroute?
Ping tests whether a destination answers. Traceroute lists each router on the path, so you can see where it stops.
What does the profiler show?
It shows which processes use the CPU, such as firewall or networking. Use it to find the cause of a high CPU load.
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