# Server racks

## Form factors

Server racks are denoted by the height, width and depth. Rack form factors are often classified by the width of the front panels, typically 19", but also 10", 23" and ETSI format.

![](/network/20210531_define-19in-rack-1.png "https://www.racksolutions.com/news/blog/server-rack-sizes/" =400x)

The available capacity is then determined by the height of the rack, measured in rack-units (1U represents 1.75" across 3 holes).

![20210531_250px-server_rack_rail_dimensions.svg.png](/network/20210531_250px-server_rack_rail_dimensions.svg.png "https://en.wikipedia.org/wiki/19-inch_rack" =x400)

Depths are more dependent on OEM standards, which is typically around 29". Audio racks tend to be [shallower](https://www.server-racks.com/rack-mount-depth.html) between 19" and 24". Browse a [rack store](https://www.racksolutions.com/server-racks) for market prices.

## Firewall: OpnSense

Note the recent [Netgear withdrawal](https://www.reddit.com/r/PFSENSE/comments/nndd9c/current_pfsense_ce_pfsense_situation_summarised/) from the popular pfSense development. OpnSense was a fork of pfSense that is feature full and similar has [rack mount options](https://shop.opnsense.com/dec3800-series-opnsense-rack-security-appliance/).

[WireGuard](https://www.wireguard.com/) as the latest alternative to OpenVPN. See the [technical whitepaper](https://www.wireguard.com/papers/wireguard.pdf).

## PoE: Power over Ethernet

Already available, but limited. Main issue being the attenuation loss of DC over long cables (using AC results in more skin conductance and crosstalk) and the switch being a single point of failure.