DNS Redirector
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FAQ 157: Monitor your DNS Redirector server with PRTG

Category: Everything else


You can use PRTG to monitor all aspects of your DNS Redirector server, see a sample screenshot.

Start by creating a new device...
- In PRTG, click Add Device
- Give your server a name, such as:  DNS Redirector
- IPv4 Address/DNS Name:  (for DNS Redirector software specify the IP you have for ListenOnIP= in dnsredir.ini)
                                         (for DNS Redirector cloud server specify the first IP of your server)

Note: For DNS Redirector cloud server skip ahead to step 6, your server is monitored 24/7/365 by our systems and staff.

Note: In the examples below you should replace "example.com" with the DNS suffix of your network, or a domain you own.

1) Create a "DNS Redirector service" sensor...
     Note: This tests that DNS Redirector is up, and it's response time.
- In DNS Redirector, add a new line to your SimpleDNS= file, such as:  10.10.10.10 dnsredir-test.example.com  (this can be any IP and made-up FQDN)
- In PRTG, click Add Sensor, DNS
- Give your sensor a name, such as:  DNS Redirector service
- Domain:  dnsredir-test.example.com
- Check result
- Value:  10.10.10.10
- Scanning Interval:  (suggested 5 minutes, meaning if DNS Redirector were to fail, PRTG in the worst case could take 5 minutes to realize it and notify you)

2) Create a "DNS internal service" sensor...
     Optional: This tests that your internal DNS server is up, and it's response time.
- In your internal/caching DNS server, add an A record such as:  10.10.10.20 dnsint-test.example.com  (this can be any IP and made-up FQDN)
- In PRTG, click Add Sensor, DNS
- Give your sensor a name, such as:  DNS internal service
- Domain:  dnsint-test.example.com
- Check result
- Value:  10.10.10.20
- Scanning Interval:  (suggested 5 minutes, meaning if your DNS server were to fail, PRTG in the worst case could take 5 minutes to realize it and notify you)

3) Create a "DNS external service" sensor...
     Optional: This tests that your ISP's recursive DNS service is working, and the response time of DNS for your domain.
- In the authoritative DNS server* for a domain you own, add an A record such as:  10.10.10.30 dnsext-test.example.com  (this can be any IP)
     *sometimes called "name servers" or "SOA servers" and may be provided by the registrar where you purchased your domain.
- In PRTG, click Add Sensor, DNS
- Give your sensor a name, such as:  DNS external service
- Domain:  dnsext-test.example.com
- Check result
- Value:  10.10.10.30
- Scanning Interval:  (no less than 8 minutes, a more frequent interval may be seen as an attack or rate-limited by your provider, which can lead to false alerts)

4) Create a "HTTP Welcome" sensor...
     Optional: Only if your DNS Redirector software is used for captive portal, otherwise skip creating this sensor.
- In PRTG, click Add Sensor, HTTP
- Give your sensor a name, such as:  HTTP Welcome
- URL:  http://192.168.x.x  (specify the IP you have for RedirectIP= in dnsredir.ini)
- Scanning Interval:  (suggested 5 minutes, meaning if the welcome site were to fail, PRTG in the worst case could take 5 minutes to realize this and notify you)

5) Create a "HTTP Blocked" sensor...
     Optional: Only if your DNS Redirector software is used for Internet filtering, otherwise skip creating this sensor.
- In PRTG, click Add Sensor, HTTP
- Give your sensor a name, such as:  HTTP Blocked
- URL:  http://192.168.x.x  (specify the IP you have for BlockedIP= in dnsredir.ini)
- Scanning Interval:  (suggested 5 minutes, meaning if the blocked site were to fail, PRTG in the worst case could take 5 minutes to realize this and notify you)

6) Create a "Clients online" sensor...
- Download DNSRedir get clients online.bat and place in C:\Program Files\PRTG Network Monitor\Custom Sensors\EXE\
- In PRTG, click Add Sensor, Custom Sensors, EXE/Script
- Give your sensor a name, such as:  Clients online
- EXE/Script, pick:  DNSRedir get clients online.bat
- Parameters:  %host
- Mutex Name:  dnsr
- Scanning Interval:  (this should be half of the number for ClientTimeout= in dnsredir.ini, so probably no less than 10 minutes)

7) Create a "Clients authorized" sensor...
     Optional: Only if your DNS Redirector software is used for captive portal, otherwise skip creating this sensor (value will always be 0)
     Optional: Only if your DNS Redirector cloud server is configured for static IPs, otherwise skip creating this sensor (value will always be 0)
- Download DNSRedir get clients authorized.bat and place in C:\Program Files\PRTG Network Monitor\Custom Sensors\EXE\
- In PRTG, click Add Sensor, Custom Sensors, EXE/Script
- Give your sensor a name, such as:  Clients authorized
- EXE/Script, pick:  DNSRedir get clients authorized.bat
- Parameters:  %host
- Mutex Name:  dnsr
- Scanning Interval:  (this should be half of the number for ClientTimeout= in dnsredir.ini, so probably no less than 10 minutes)



 
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