HON95-wiki/config/network/linux.md

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title: Linux Switching & Routing breadcrumbs:

• title: Configuration
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Using

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• Debian 10 Buster

Foreword

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Using Linux servers as switches and routers may often be an inexpensive option and allows you to implement most network functionalities in one box. They may be virtualized to possibly reduce power usage and noise and take up no physical space. It is generally more unreliable than using enterprise routers and switches, though, and may require a good amount of time troubleshooting performance issues at times. The issues may not become apparent until tested live with tens to houndreds of clients, as a simple throughput test will not uncover bottlenecks related to large amounts of connections (which can be hard to test realistically in lab environments). Issues may also be related to stupid things like which ports you're using on the same NIC.

Setup

• Setup the Linux node as described in Debian Server: Basic Setup.
• Setup the firewall for filtering both forwarded traffic and input/output to the router.
• Setup the firewall for NAT.
• Enable IP forwarding in /etc/sysctl.conf, then run sysctl -p:
  • net.ipv4.ip_forward=1
  • net.ipv6.conf.all.forwarding=1
  • Run sysctl -p to reload.
• Setup the network interfaces for all the directly connected networks.
• Setup a default gateway, static routes and/or routing protocols.
• Setup radvd for IPv6 NDP.
• (Optional) Setup a DHCPv6 server like the ISC DHCP Server.
• Setup a DHCP server like the ISC DHCP Server.
• (Optional) Setup a DNS server, like Unbound.
• TODO Multicast routing.

Tuning

• Disabling dynamic frequency and voltage scaling (Intel SpeedStep).
• Disabling multithreading (Intel Hyper-Threading).
• Make sure network interrupts are distributed across all cores.

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