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Eric Johnson
Asked: 2017-02-23 13:47:03 +0800 CST

NAT 169.254.*.* ip address to 192.168.*.*

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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?

nat local-area-network

2 Answers

  1. Best Answer

    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.

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  2. 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

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