APC PDU configuration trick

I was trying to configure an APC7811 PDU, which has a network port for remote access. It’s a metered PDU so you can log in remotely and look at power consumption.

I’d never had to configure one before so I just popped in the CD that came with it and tried to configure an IP address by using the discovery tool. Regardless of which IP address I tried, I kept getting “The IP is already in use on the network.”

This configuration method is in the documentation, but it’s buried at the end… I think I’ll use this every time now as it’s fast and doesn’t require the vendor’s CD.

The MAC address is on the back of the PDU and on the Quality Assurance slip included in the package.

  1. Use ARP to define an IP address for the PDU,
    and use the PDU’s MAC address in the ARP
    command. For example, to define an IP
    address of 156.205.14.141 for the PDU that has
    a MAC address of 00 c0 b7 63 9f 67, use one
    of the following commands:

    Windows command format:
    arp -s 156.205.14.141 00-c0-b7-63-9f-67

    LINUX command format:
    arp -s 156.205.14.141 00:c0:b7:63:9f:67

  2. Use Ping with a size of 113 bytes to assign the
    IP address defined by the ARP command. For
    example:

    Windows command format:
    ping 156.205.14.141 -l 113

    LINUX command format:
    ping 156.205.14.141 -s 113

  3. Use Telnet to access the PDU at its newly
    assigned IP address. For example:

    telnet 156.205.14.141

  4. Use apc for both user name and password.

At this point the IP address is configured for the interface, you can browse to the IP via HTTP. Don’t forget to delete your static ARP entry.

22 thoughts on “APC PDU configuration trick

  1. Pingback: APC Switched PDU 7921, ARP adventure! – Emu Wars

    1. pkremer Post author

      Theoretically if you plug the PDU into a managed switch, you should see the mac address in the switch’s address table (.ie. show mac address-table on a Cisco switch). If the PDU has a static IP on it and for some reason isn’t generating any traffic, you might have to do a hard reset. Then when you plug it in the PDU should issue a DHCP request and then you’ll see the MAC.

      Reply
  2. Tom

    I was very fortunate that I did a little Google search and found this. It took all of 10 minutes from the time I read this note to getting the PDU set up. I was also lucky that it still had the default user name and password which made it easy. Thank You very much. Tom

    Reply
  3. Spencer C

    I just ran across this issue and used the netsh neighbors command. Below is the example of what I did to achieve the same results. My network interface was my wifi adapter, your’s might be Local Area Network, etc. The MAC is x’ed out. I was then able to access the Metered PDU via http. The model I did this against was apc pdu 885-1736.
    ——————————————————————-

    C:\WINDOWS\system32>netsh interface ipv4 add neighbors “Wi-Fi” 192.168.1.10 XX-XX-XX-XX-XX-XX

    C:\WINDOWS\system32>ping 192.168.1.10 -l 113

    Pinging 192.168.1.10 with 113 bytes of data:
    Reply from 192.168.1.10: bytes=113 time=102ms TTL=255
    Reply from 192.168.1.10: bytes=113 time=4ms TTL=255
    Reply from 192.168.1.10: bytes=113 time=3ms TTL=255
    Reply from 192.168.1.10: bytes=113 time=5ms TTL=255

    Ping statistics for 192.168.1.10:
    Packets: Sent = 4, Received = 4, Lost = 0 (0% loss),
    Approximate round trip times in milli-seconds:
    Minimum = 3ms, Maximum = 102ms, Average = 28ms

    Reply
  4. Luca

    Hello,
    I have a apc ap7920 that used in webfarm, now I want to set it up again, but I can not connecting to the router to assign an ip … how can I do?
    thank you

    Reply
  5. hirni

    Interesting entry point.
    OTOH – I went down a different path, as I got a PDU, which was already configured:

    a.) find out it’s MAC address.
    either printed on the pdu, or via some ‘other’ means – like the MAC-table of your (managed) switch.

    so let’s assume I have: 00:c0:b7:31:91:8d

    b.) then – on a linux-client ‘snoop’ for this address:

    tcpdump -i eth0 ether host 00:c0:b7:31:91:8d

    …normally – if you reboot/reset/restart/power-cycle the pdu – it should spit out some ARP requests for ‘some’ configured IPs (like log-server, time-server)
    …and voila – you have the IP-address.

    c.) again assuming you’re on a different network:
    Let’s say your ‘normal’ eth0-net is 192.168.1.10
    And let’s assume the PDU ‘said’: 172.16.10.10

    ifconfig eth0:1 172.16.10.1 netmask 0xffffff00

    d.) ping 172.16.10.1 – if it answers – OK, if no answer:
    likely your netmask isn’t correct, and you need to try some other netmasks (but typically it’s ok with /24)

    e.) telnet / http / ssh test-access the pdu.

    I got lucky – the username/pass was still ‘apc/apc’ – so I could configure it – for my network (DHCP) 🙂

    Reply
  6. matt

    Great post! I’ve been fighting with this thing and it’s still not working. I have it on my home network using a regular cat 5 Ethernet cable. Do you need to use a crossover cable and directly connect it to your pc? For as much as these devices cost I can’t believe how old school this config is! Thanks a TON!

    Reply
    1. pkremer Post author

      As long as you’re on the same broadcast domain, the trick should work. When I wrote the post, the PDU and my laptop were connected to a Cisco 3750 switch and on ports in the same VLAN. If you’ve got a simple home switch like a Linksys or whatever, you should just be able to plug both into your switch. But it wouldn’t hurt to plug directly in via crossover cable, I’d expect that to work as well.

      Reply
  7. Val Langmuir

    I spent I think 2 hours trying the APC config wizard and it kept failing with stupid errors. When I tried the manual command, it sensibly told me I needed to run as administrator. In all fairness the app would have probably worked fine if I had thought to “run as admin”. But your trick is way smoother and worked perfectly! Thanks!!

    Reply

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