Identify IP Address Conflicts

Objectives

Discover possible IP conflicts on a customer's network

Prerequisites

1. Terminal is powered on
2. Terminal is configured to use a static IP address.
3. Link and activity lights on terminal network port are on.
4. SSH Access to Terminal/Server. It must be on the same subnet. There is no work-around for this.
5. IP Address of the potential conflict OR SSH access to the customer's FullCount VM, or access to the FC_OBJ_ADMIN schema on "odbprod01.fullcount.net"

Instructions

1. Record the serial number of the terminal that you suspect may have an IP address conflict.
2. Determine the last known IP address for the terminal that you suspect may have an IP address conflict.
1. If the terminal is configured to use a static IP address, check notes in Tracker.
2. If you have access to the FC_OBJ_ADMIN schema on "odbprod01.fullcount.net", check the COMPUTER_NET_SETTINGS table.
3. If you have access to the customer's FullCount VM, search Apache access logs for the serial number and IP address.
3. Log into another terminal or VM on the same subnet.
4. The ARP protocol is not routable, so the other terminal or VM must be on the same subnet. There is no way to work around this.
5. Try to log into the terminal you suspect may have an IP address conflict via SSH.
1. If you receive an error message that says something like "ssh: connect to host xxx.xxx.xxx.xxx port 22: Connection refused", either you have the wrong IP address for the terminal, or there may be an IP address conflict.
2. If you're able to log into the terminal, but you can't keep a connection to it, there may be an IP address conflict.
6. Run the following command from the FullCount server to see the ARP table for the network which maps IP address and MAC address.

# arp -an

7. This will display a list of all network devices in the ARP table. Identify if the IP address you are using is in the table. If it is in the table, write down the MAC address.

8. Query the COMPUTER_NET_SETTINGS table on FC_ADMIN for the IP address is question. Compare the MAC address in the ARP table with the MAC address in the COMPUTER_NET_SETTINGS table. If they match, then the IP is currently registered to the FullCount terminal. If it does not match, a different device is using the IP address.

9. You can try and utilize the following website to match the MAC address found in the ARP table with the manufacturer of the hardware. This will not tell us what the machine is exactly, but can help point in the right direction.

1. This is much more difficult than it sounds because the name of the company that manufactures the hardware almost never matches the name of the vendor the hardware was purchased from. It is very difficult to give advice about how to do this because hardware changes constantly. Two devices with the same part number may be manufactured by different companies at different points in time. (Pioneer does this frequently.)

http://standards.ieee.org/develop/regauth/oui/public.html

10. Communicate with customer at local community to try and identify what type of device it is and to get the IP addresses changed.