Understanding IP settings

Identify your IP address. Make sure you are looking at the settings for your wired Ethernet card (not wireless, dialup, PPP, loopback, etc.).

If you get an error or no Ethernet card is detected:

The operating system is not recognizing the Ethernet card or is otherwise unable to use it. Verify that the computer has an Ethernet card installed. Check the Device Manager (or System Profile or dmesg) to make sure the Ethernet card is recognized by the operating system. You may have a defective Ethernet card, but more likely you just need to load Ethernet or network drivers. On Windows computers, network problems are frequently caused by spyware.

If you get a 169.x.y.z IP address:

This is a "link local" address. The computer is unable to get IP settings from the DHCP servers, most likely because the computer cannot find the DHCP servers. DHCP is available in most locations at WHOI. Check that the computer is plugged in with a working Ethernet cable to a working (activated) Ethernet jack. Some operating systems will tell you whether the link is active; some Ethernet cards have link lights. If the computer is plugged in to a personal switch, make sure that there are link lights on both the uplink port (connected to the Ethernet jack) and the port that the computer is connected to. Try resetting the switch. NetReg DHCP will not work behind a NAT/firewall. If you are using an Ethernet jack that you have not used before, it may not be activated. If possible, test this by plugging another (known good) computer in to the jack with a (known good) Ethernet cable. For Windows computers which used to work on the network and have not moved, check for spyware and viruses.

If you get a 192.168.x.y IP address:

This is a private IP address. If you get such an IP, you may be plugged in to a NAT/firewall. Usually, this is a router. Maybe there is something wrong with it. If you are unable to access the network, try connecting directly to WHOInet.

If you get a 10.202.x.y IP address:

You are looking at the settings for your wireless card, not your wired Ethernet card. Make sure your wireless card is disabled and check your wired Ethernet settings.

If you get a 10.128.x.y IP address:

The computer has a physical network connection and is able to get to WHOI's DHCP servers. However, the DHCP servers do not think you are authorized to use the network (at least from your current location). If your computer is new to WHOInet, you will need to register it. If your computer is not new to WHOInet, you may need to update your registration. Most likely, you need to update the hardware (MAC) address; a computer's hardware address changes if its Ethernet, motherboard, etc. is replaced.

If you get a 128.128.x.y IP address:

The computer is getting a valid IP address from the DHCP server and should be able to use WHOInet. If you are not able to access anything on the network, try releasing and renewing your IP settings (DHCP lease). If you still have no access, you may have DNS problems, spyware, a virus, or be blocked for network security reasons. See the additional debugging tips below.

If you get some other IP address:

Either DHCP is failing and you are seeing a cached IP (such as an IP you used on a non-WHOI network, for wireless, or dialup), or you are not using DHCP, or there is a rogue DHCP server on your subnet. Switch to DHCP and/or release and renew your IP settings (DHCP lease). If problems persist, you may need to contact the CIS Help Desk and provide your MAC address, the IP address you are receiving, and the IP address of the DHCP server if given.