How to turn anything into a router • Hacker News Board

Re: How to turn anything into a router

#201

Post by sophacles » Mon, Mar 30, 2026, 9:47 PM UTC

colinb wrote: post #41

louwrentius wrote: post #19

Earlier quoted context omitted.

A CPU from the last 20 years can route traffic at gigabit speed. It's only something to worry about for a Raspberry Pi3 or something similarly 'crippled'.

I think I understand why this is true for plain IP forwarding. There isn’t much to break the cache and the lookups are few and fast. What’s the cheapest (new) computer that can drive a 1Gb port with NAT? With a busy encrypted (wireguard?) connection? [I don’t think qos has a lot of use in the domestic environment; sure, someone here does it but I think it’s much less mainstream than the features I already mentioned.…

I can drive 2+ Gbps vrfs, nats, ipsec, complex firewall rules and several routing tables through an Atom C3558. This is just using stock linux kernel networking. There are other services running on that box too.

Depending on details, it can go higher (e.g. without the ipsec being handled on the atom box, and using the 10G ports built into the chip, offload becomes helpful for TCP and UDP flows).

This is traffic in one 10G port and out the other, in this case. Multiport flows were not tested since they were out of spec for the use case.

This is not a one off - this is a product I built and has been tested in many deployment scenarios. (I can't provide more details due to employment reasons, and I won't name the employer)

Re: How to turn anything into a router

#202

Post by hedora » Mon, Mar 30, 2026, 10:05 PM UTC

leptons wrote: post #120

x0x0 wrote: post #110

Earlier quoted context omitted.

The policy rationale is the Trump admin takes bribes to permit router imports. No different than how various companies won tariff exemptions.

That, and like drones, maybe one of his kids starts up a router company which becomes the sole company allowed to sell routers in the US.

And, like news networks, maybe the router companies are forced to let him hire a censor (they like to call them ombudsmen) so the white house can real-time block inconvenient traffic.

Re: How to turn anything into a router

#203

Post by icedchai » Mon, Mar 30, 2026, 10:08 PM UTC

nickdothutton wrote: post #94

When I got started, the NSFnet backbone was a bunch of IBM RS/6000 systems with comms cards. There were no routers.[1] [1] https://www.rcsri.org/collection/nsfnet-t3/

There were routers, just no T3 (45 megabit) capable routers.

Re: How to turn anything into a router

#204

Post by [deleted] » Mon, Mar 30, 2026, 10:18 PM UTC

forinti wrote: post #172

mintplant wrote: post #170

This seems like it might be a good place to ask: does anyone know of a low-cost, readily-available SBC box with built-in dual Ethernet interfaces? I've been very interested in some of Radxa's boards in the ~$30-70 range, like the E52C [0] and the E20C [1], but they don't have many distributors and seem to have stocking issues [2]. [0] https://radxa.com/products/network-computer/e52c/ [1] https://radxa.com/products/ne…

Banana Pi makes SBCs with lots of networking ports.

[deleted]

Re: How to turn anything into a router

#205

Post by ssl-3 » Mon, Mar 30, 2026, 10:19 PM UTC

bluedino wrote: post #47

This really takes me back. My first actual 'use' for Linux was making routers out of leftover computers. The perfect machine back then was a 100MHz Pentium, in a slimline desktop case. At the time, the Pentium III was the current desktop chip, so you'd have a pile of early Pentium-class machines to use. And even a 10mb ISA network card (3Com if possible) would have plenty of power for the internet connections of the…

You guys with your dedicated hardware. :)

I did routing duties for my LAN with my primary desktop for about a decade, variously with Linux, OS/2 (anyone remember InJoy?), and FreeBSD -- starting with 486 hardware. Most of that decade was with dial-up.

The first iteration involved keying in ipfwadm commands from, IIRC, Matt Welsh's very fine Running Linux book.

WAN speeds were low; doing routing with my desktop box wasn't a burden for it at all. And household LANs weren't stuffed full of always-on connected devices as they are today; if the Internet dipped out for a few minutes for a reboot, that wasn't a big deal at all.

I stayed away from dedicated hardware until two things happened: I started getting more devices on the LAN, and I saw that Linksys WRT54G boxes were getting properly, maturely hackable.

So around 2004 I bought a WRT54GS (for the extra RAM and flash) and immediately put OpenWRT on it. This lead to a long rabbit hole of hacks (just find some GPIO lines and an edge connector for a floppy drive, and zang! ye olde Linksys box now has an SD card slot for some crazy-expensive local storage!).

I goofed around with different consumer router-boxes and custom firmware for a long number of years, and it all worked great. Bufferbloat was a solved problem in my world before the term entered the vernacular.

And I was happy with that kind of thing at home, with old Linksys or Asus boxes doing routing+wifi or sometimes acting as extra access points... until the grade of cheap routers I was playing with started getting relatively slower (because my internet was getting relatively faster) and newer ones were becoming less-hackable (thanks, binary blob wifi drivers).

---

I decided to solve that problem early in 2020. Part of the roadmap involved divorcing the routing from the wifi completely -- to treat the steering of packets and the wireless transmission of data as two completely distinct problems.

I used a cheap Raspberry Pi 4 kit to get this done. The Pi4 just does router/DNS/NTP/etc duties like it's 1996 again. Dedicated access points (currently inexpensive Mikrotik devices) handle all wifi duties.

That still works very well. Pi4 is fast enough for me with the WAN connections available here (which top out at 400Mbps) even while using SQM CAKE for managing buffers, and power consumption of the whole kit is too low to care about.

The whole OpenWRT stack just plods along using right around 64MB of RAM. VLANs are used to multiply the Ethernet interface into more physical ports (VLANs were used to do this inside the OG WRT54G, too).

It's sleepy, reliable, and performant.

---

And it'll keep being fine until I get a substantially-faster WAN connection. For that, maybe one of the China-sourced N150 boxes, with 10gb SFP+ ports, will be appropriate -- after all, OpenWRT runs on almost anything including AMD64 and the UI is friendly-enough.

But there's no need to upgrade the router hardware until that time. Right now, all of my routing problems are still completely solved.

Re: How to turn anything into a router

#206

Post by zymhan » Mon, Mar 30, 2026, 10:22 PM UTC

mintplant wrote: post #170

This seems like it might be a good place to ask: does anyone know of a low-cost, readily-available SBC box with built-in dual Ethernet interfaces? I've been very interested in some of Radxa's boards in the ~$30-70 range, like the E52C [0] and the E20C [1], but they don't have many distributors and seem to have stocking issues [2]. [0] https://radxa.com/products/network-computer/e52c/ [1] https://radxa.com/products/ne…

If you're okay with used, I got an "industrial" mini PC with loads of connectivity for maybe $125? https://support.onlogic.com/product-documentation/industrial... And there are plenty of configurations at lower prices, as well as many other manufacturers in this space.

Re: How to turn anything into a router

#207

Post by zymhan » Mon, Mar 30, 2026, 10:24 PM UTC

drnick1 wrote: post #158

> While it may seem appealing, I would highly recommend against installing loads of software right on the router, and instead forward traffic to a device in a DMZ or VLAN. Why not? I use an old gaming PC as a "router" (machine exposed to the WAN), and run dozens of services on it besides the firewall/NAT (iptables). Among others: email, Web server, multiple game servers, and many internal services (DNS, hostapd, load…

As others stated, installing software can change the state of your firewall configuration, or start a service listening on 0.0.0.0:8080 for example.

Re: How to turn anything into a router

#208

Post by baby_souffle » Mon, Mar 30, 2026, 10:54 PM UTC

eptcyka wrote: post #151

dlenski wrote: post #112

This is a great writeup! Perhaps I can put in a plug for the create_ap script which I have been maintaining for many years ( http://github.com/dlenski/create_ap ). It's a shell script that allows you to turn any ol' Linux computer into a WiFi router in one quick command-line: By default, it will setup your WiFi card as an access point (allows WPA2/3, MAC filtering, etc), setup packet forwarding and routing, and run a…

Any tips on good wifi chipsets that do not suck in AP mode?

Which bands and capabilities did you have in mind? For a basic 2.4 GHz, almost anything at this point. Intel and some iteris chipsets are well supported.

mt7996 is good for wifi 7. You can also check the suggested hardware list on the kismet project for good recommendations for older bands and protocol versions

Re: How to turn anything into a router

#209

Post by bombcar » Mon, Mar 30, 2026, 11:06 PM UTC

esseph wrote: post #180

doubled112 wrote: post #173

Earlier quoted context omitted.

Like most things, really. I used to build routers from old PCs, but eventually those tiny appliances caught up with the performance/functionality I need. You can do a lot of routing on a $70 Mikrotik, although they might not be "easy".

I really want to end up with one of these for at least a few months: https://mikrotik.com/product/rds2216

At $2k out the door that's way more reasonable than I thought it'd be.

Too bad I can't fill it with old spinning rust.

Re: How to turn anything into a router

#210

Post by novachen » Mon, Mar 30, 2026, 11:19 PM UTC

doubled112 wrote: post #156

smashed wrote: post #30

Lots of "just use X" comments but the article is about showing the bare minimum/how easy the core part of routing actually is. Also, if you have ever used docker or virtual machines with NAT routing (often the default), you've done exactly the same things. If you have ever enabled the wifi hotspot on an android phone also, you've done pretty much what the article describes on your phone. All of these use the same Lin…

Basically any computer is a router if you're brave enough. Windows PCs had (have?) that Internet connection sharing feature for a long time. It was really just a checkbox to enable NAT too. Sometimes I think combining a firewall/router/switch/AP/file server/etc into a device called a "router" really confuses people. Even people who should know better.

the naming is part of the confusion. consumer "routers" are really NAT gateway + DHCP server + DNS cache + WiFi AP + maybe a firewall, all in one box. separating them makes each piece clearer.