1

I have a piece of machinery that has a static IP in the range of 169.254.. and can not be changed. I need to access this from another network. My thought is to use a router, and have the WAN port be the 192.168.. device and the LAN port be the 192.168.. device. I have tried configuring a router with the LAN address of 169.254.1.1 but it does not like this IP address. What else can I do to accomplish this NAT?

  • 4
    169.254.*.* is the link-local address block for IPv4. The behavior you're experiencing is exactly what I'd expect. If the device can't have it's IP changed because you can't access it.. you need to add an IP on that range to a pc/laptop, then go and configure an IP on the subnet you want it on. If the device literally does not allow you to change the IP and only has a link-local address.. you're likely SOL. Contact the vendor. – yoonix Feb 22 '17 at 21:51
4

The IPv4 169.254.0.0/16 range of addresses is Link-Local, and it cannot be routed.

See RFC 6890, Special-Purpose IP Address Registries:

                +----------------------+----------------+
                | Attribute            | Value          |
                +----------------------+----------------+
                | Address Block        | 169.254.0.0/16 |
                | Name                 | Link Local     |
                | RFC                  | [RFC3927]      |
                | Allocation Date      | May 2005       |
                | Termination Date     | N/A            |
                | Source               | True           |
                | Destination          | True           |
                | Forwardable          | False          |
                | Global               | False          |
                | Reserved-by-Protocol | True           |
                +----------------------+----------------+

                        Table 5: Link Local

Also, addresses in that range cannot be statically assigned because they cannot perform the duplicate address detection and change addressing if a duplicate is found.

See RFC 3927, Dynamic Configuration of IPv4 Link-Local Addresses:

1.6. Alternate Use Prohibition

Note that addresses in the 169.254/16 prefix SHOULD NOT be configured manually or by a DHCP server. Manual or DHCP configuration may cause a host to use an address in the 169.254/16 prefix without following the special rules regarding duplicate detection and automatic configuration that pertain to addresses in this prefix. While the DHCP specification [RFC2131] indicates that a DHCP client SHOULD probe a newly received address with ARP, this is not mandatory. Similarly, while the DHCP specification recommends that a DHCP server SHOULD probe an address using an ICMP Echo Request before allocating it, this is also not mandatory, and even if the server does this, IPv4 Link-Local addresses are not routable, so a DHCP server not directly connected to a link cannot detect whether a host on that link is already using the desired IPv4 Link-Local address.

Administrators wishing to configure their own local addresses (using manual configuration, a DHCP server, or any other mechanism not described in this document) should use one of the existing private address prefixes [RFC1918], not the 169.254/16 prefix.

1

Industrial equipment that have a fixed address can be linked via NAT an router such as A-B 1783-NATR. One requirement for 1:1 NAT routing is that the public and private side must be completely different network addresses. Public might be: 169.156.1.x, private might be 192.168.1.x

Link http://ab.rockwellautomation.com/Networks-and-Communications/Network-Address-Translation-Device

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.