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July 2021

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[ISG News] D-PHYS network migrations
by Claude Becker 07 Jul '21

07 Jul '21

ISG News has posted a new item, 'D-PHYS network migrations' Several network migrations will take place over the next months that will have an impact on the design and inner workings of the ethernet network at D-PHYS. Even though all hosts will be affected at a technical level, we believe that most changes will not require any involvement from your side. By the end of the year this should further increase the fault-tolerance of the cabled network infrastructure and enhance the security of the bulk of the computers at D-PHYS. Network segmentation The central Informatikdienste are splitting several networks into smaller chunks to increase the overall stability and fault-tolerance. Unfortunately the details are flagged as confidential, prohibiting us from exposing the precise structure of this segmentation. The main repercussion is that our D-PHYS networks will no longer be able to span across all current buildings at once. So depending on the building, we will have to introduce new subnets and assign new IP addresses to the computers inside. NAT network Motivated by the above-mentioned segmentation as well as security considerations, we are planning to migrate a large number of hosts to a NAT network. This means that the computer will only get an ETH-internal IP address and will no longer be directly reachable from outside of ETH. From inside ETH or VPN, all communication with that computer remains unaffected. However, while the host can still communicate with all of the internet, it will no longer be exposed to direct attacks from the outside. We believe that this is a very sensible default for most computers and laptops. Of course it will still be possible to assign a public IP to selected hosts in order to provide a specific service to the outside. The new NAT network also provides DynDNS with sentname.dhcp-int.phys.ethz.ch hostnames and full IPv6 connectivity. So if you rely on DNS entries for dynamic IP addresses, make sure to use the domain dhcp.phys.ethz.ch for public subnets and dhcp-int.phys.ethz.ch for internal subnets. DHCP migration Right now, some of our networks are serviced by our own D-PHYS DHCP servers, while others use the DHCP servers of central IT services. We are now consolidating all networks and migrating the remaining ones step-by-step to the DHCP servers of Informatikdienste. This change is mostly technical and should remain unnoticed by most users. For further details and up-to-date information please refer to our readme page. You may view the latest post at https://isg.phys.ethz.ch/2021/07/07/d-phys-network-migrations/ You received this e-mail because you asked to be notified when new updates are posted. Best regards, Claude Becker becker(a)phys.ethz.ch

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