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University Technology Services


Use of Private IP Address Space

This document describes the use of private address space at McMaster University. It is recommended that you avoid making private address space assignments which conflict with the University allocations to avoid possible future problems.

If you have any questions, or are unable to resolve your issue, support can be received via the Service Desk

Service Desk

McMaster University is assigned the IPv4 address space, which is a range of addresses extending from – This address space is referred to as Public Address Space because it is globally unique and can be routed over the Internet. However, as the University network grows, our IPv4 allocation is no longer sufficient to continue using it exclusively for addressing devices on the campus network.

Expandable List

You many have noticed some devices using other address blocks, like, which is allocated to the wireless network. The formal names for those addresses are RFC1918 or private address space. Private address space can be routed internal to organizations like McMaster but not to the Internet. Devices assigned a private network address can reach the Internet using a process called Network Address Translation (NAT) which translates the private address to an external, publically routed, address in our IPv4 address block (i.e. devices external to McMaster University will continue to see our familiar public address block). The process is entirely transparent to the end user. The Internet Assigned Numbers Authority (IANA) has reserved the following IPv4 address ranges for private networks.

UTS does not plan to allocate either of the first or last address blocks. The reason being they are the most common of the private address space and are used extensively on home routers and other private networks. Feel free to assign networks from or for your local network needs but keep in mind these networks will not be routed within our network.

Technology Services is making use of the block of addresses denoted and you should avoid using this address space inside the McMaster network. When allocated, these networks will route through the campus network in exactly the same manner as addresses do. That address block is currently allocated as follows:

The remaining network blocks in the range will be allocated as needed. Please avoid using them for your internal projects.

Those configuring a firewall or other Access Control Lists (ACL) and need to identify McMaster University networks, should configure those devices to trust these networks.

All other networks should be considered external to McMaster University.