OpenWRT Serial Console Server - Opengear Alternative

Are there any devices that:

  • Support OpenWRT
  • Have 1 or more RJ45 Serial Ports
  • 1 or 2 Ethernet Ports
  • Support LTE

Ideally I am looking for something that has 4 serial ports to be used as a console server to replace something like an OpenGear. My guess is there are quite a few that have 1 serial port, but very few that have more than 1?

would USB based serial ports be an option ?

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Yes, though built in like an opengear would be prefered. What external option do you recommend?

Do you want a real RS-232 serial port, with RS-232 voltage levels and all the extra handshake/modem control pins, or is logic-level 5 V or 3.3 V Tx/Rx pins sufficient? I suspect the latter is what you want since 3.3V Tx/Rx is usually what serial consoles actually use.

I didn't realize there was any differences. I am looking to be able to use this as an out of band console server to console to Juniper, Cisco, and other network devices that have a serial port built in. This would replace an opengear. Which of the two options you presented is needed for that?

USB hub + Nx USB-to-RS232 adapters

Cisco standard is RS-232 levels on an RJ45 plug. There are USB to serial adapters that do this within one cable. There are probably also mulitport versions. Openwrt has drivers for all the common USB to serial chips.

I've built several of these using picocom as the login shell process, so someone who connects SSH to a particular Dropbear instance is immediately connected to the serial console.

I found https://www.assured-systems.com/us/2-or-4-port-pci-express-rs-232-serial-communication-card-db9-or-rj45/ earlier, but it sets the size of the box you'll need, to be able to fit it, or similar cards.
Another issue could be the driver they use, it might not be packaged for openwrt.

Probably easier to find a DB9 RS232 multi port device, and buy DB9->RJ45 cables, like https://www.reichelt.com/de/en/usb-2-0-converter-usb-a-to-4x-rs-232-2-0-m-exsys-ex-1324-p328039.html or an USB hub + https://www.delock.com/produkt/63911/merkmale.html.

https://freetserv.github.io/

Should run OpenWrt just fine. You could even modernise it with a Rpi4 or 5. Will require some work to assemble...

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Yes. I've been using an Edgeport/4 for this purpose for ages. Should be possible to pick one up for å reasonable price on eBay.

https://www.digi.com/products/networking/infrastructure-management/usb-connectivity/usb-to-serial/edgeport

Or get a usb hub and some usb A to cisco rj45 serial cables. Probably cheapest and cleanest, avoiding all the DB9 connectors. Edit: right, that was what you just said:)