online device monitoring

To know what is inside

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Fast track details

DD-WRT v2.4 or at least v2.3 SP3

Do following steps to add your DD-WRTv24 for monitoring:

  1. Prerequisites
    • Public IP on Your DDWRT box or configured port forwarding so that snmp is accessible from servers
    • DDWRTv24 with SNMP service (std or greater release)

  2. Enable SNMP service. Login to ddwrt web panel, go to 'Services' tab (Services sub tab), scroll down to SNMP, click enable and then set RO community to Your secret string (it will be kind of a password).
    You might also set name for the device. All other fields are not mandatory. Click 'Apply settings' what

  3. Enable queries. Go to 'Administration' > 'Commands' and paste command
    /usr/sbin/iptables -I INPUT 1 -p udp --dport 161 -s -j logaccept
    and click 'Save firewall'.
    If you have DMZ enabled, please do the following: go to 'NAT/QoS' > 'Port Forwarding' and add following rule:
    App: snmp; Port from: 161; Protocol: UDP; IP Address: LAN or WAN ip of the router; Port to: 161; Enabled: Yes. Click Save and Apply

    If You already have an entry in the firewall, copy previous entries to Commands text area and add below for odmon and the click 'Save Firewall'
    This will add entry to Your firewall, which allows pollers to read snmp data required for monitoring.

  4. If You want the SNR graph for one host created, make sure there is at least one wireless host associated. The graph will be created for host that associated as the last one
  5. If at any time graphs will start to show wrong values e.g.that there is one host associated, when there will be none, it means that (run by snmpd) is working bad. I do not know why is happens, but solution is to restart from time to time. You can do this by going to Administration - Management and enable such Cron entry:
    */15 * * * * root /usr/bin/killall

    This will kill the, which then will be run by snmp whenever poller ask for snmp value

  6. Test SNMP.
    After reconfiguring Your device please do the snmp test to make sure it will be working correctly.
    For security reasons it is allowed to query only system description (sysDescr, OID . standard value.
    Please specify hostname, snmp community and snmp version
    IP or hostname:

    : Use my detected IP

    SNMP Version

Graphs. This fast track will create following graphs for Your device: bandwidth on interfaces, CPU, memory, load average, number of associated wireless clients, SNR of one wireless client (the one connected as last). After graph creation, wait 5 minutes for them to show up. Graph examples can be viewed here. The SNR graph is unfortunately not "stable" so once you start monitor one client, it might be replaced with other client without your knowledge. This is a DD-WRT problem, where snmp index is not persistent and dynamically allocated for associated host in the newest first method, making it impossible to follow up.

Make sure that You have configured and tested the SNMP on Your DDWRT box. If everything is working fine, press Next