I need mgetty for latest OpenWrt snapshot for retro dial-up server

For Developers
1

I want to make a simple dial-up server using dogemicrosystems's guide and would like to use the minimal amount of hardware, thus a custom OpenWrt build for Arcadyan VGV7510KW22 (o2 Box 6431) + USRobotics USR5637 USB 56k modem seem the best choice.

However it seems that the mgetty package is no longer available in the latest code from git.
How can I add it back? Or should I just use an older release codebase - in that case, how can I find out when mgetty was removed?

Thanks! :slight_smile:

2

As far as I can find, the last trace of mgetty is from 2014, before the packages were moved to GitHub.

https://git.openwrt.org/?p=openwrt/svn-archive/packages.git;a=blob;f=utils/mgetty/Makefile;hb=HEAD

Looks like nobody has been interested in the packages since then, and nobody has assumed the maintainership and imported it into the "new packages feed" in GitHub (which has been the current one since 2014...).

...too far away in history to be useful...

3

I believe agetty should support dialup modems too. But you are way into pre-historic hardware and should not expect any ready-made or tested software solutions....

1 Like
4

@hnyman @bmork Thanks for your feedback! This is for a retrocomputing project at the Slovenian Computer Museum where I volunteer :slight_smile: I have the whole setup working great with a Raspberry Pi but would like to shrink it down to one device (+ USB modem attached to it) in a kind of "dial-up ISP in-a-box" way.

I have now "downgraded" to OpenWrt 15.05.1 "Chaos Calmer", am building it in Debian Jessie and will try using this mgetty feed next: https://github.com/adrianguenter/wrt-packages

Update: Managed to build it! Now will test the x86 build since my o2 box arrives next week.
Update 2: I realized I will also need to get asterisk_channel_lantiq working :slight_smile: More info to follow...

5

New updates:

  • Even though I was able to build mgetty for OpenWrt 15, I was then unable to make a successful build with asterisk and asterisk_chan_lantiq
  • I then tried OpenWrt/LEDE 17 but also encountered compile errors beyond my ability to fix
  • Then I reverted back to the latest openwrt from git and fixed mgetty compile errors - I have documented everything in my repo and attached the mgetty package Makefile and patches
  • I am compiling everything on Windows 10 WSL2 and it works great - note that I have not received the o2 box yet so am unable to test on real hardware yet
  • Will keep you updated :slight_smile:
6

Big update! :slight_smile:

I received the o2 Box 6431, built OpenWrt including mgetty, figured out asterisk and managed to get a connection from my Windows 95 machine using an external U.S. Robotics modem.

I have moved the repo with all the instructions and changed config files to this location: https://github.com/markostamcar/muzej.si/tree/master/dial-up/openwrt

Unfortunately, as of 14. April 2021, my setup has a big issue:

  • The modem connection quality is extermely poor - just 2400 bps :frowning: Ping from OpenWrt to client machine works (1000-2000 ms), but that's about it. I can hear during the modem negotiation phase that the beeps are not what is expected for a 33600 bps connection - they sound very distorted.
  • I have tried different settings and codecs in lantiq.conf but was unable to get any improvements - is there a way to set up a raw, uncompressed PCM audio path?
  • I am new to asterisk: I hope my approach of directly connecting analog phone ports to each other without SIP is good (I figured, the fewer middlesoftware, the better) - see extensions.conf

And perhaps the biggest question of them all:

  • Is the Lantiq SLIC120 even capable of making a high-quality connection between two analog modems or is it meant just for voice calls?

CC @Plonk34 (also sent an e-mail to mr. Stefan Koch)

7

As there are some devices supporting fax functionality (AVM comes to mind), at least 14.4 KBit/s should be attainable (with the usual caveats of fax in a VoIP world).

8

Thanks, makes sense, it even has a little fax icon next to FXS port 2.
I will try with a hardware modem instead of the USB one to see if it works any better.

9

I tried using USB pl2303 serial dongle + another old external modem (so there are external modems on both ends) but the results weren't any better.

I also recorded the 2400 bps handshake - to me, it sounds weird even at the beginning (where there is a pulsating noise in the background) :confused:

I then experimented with rxgain/txgain in lantiq.conf and there were some improvements - if I increased them to around 7, sometimes I would get a 28800 bps connection, however it would soon drop due to it still being of bad quality.

So it seems in theory it would be possible to find a sweetspot with the lantiq.conf parameters, but there are just so many :frowning:

10

@mkresin CC @blogic I just saw the option "fax relay and modem support" is off by default in https://github.com/openwrt/openwrt/blob/master/package/kernel/lantiq/ltq-tapi/Config.in#L1

Is this something that could help in my attempt to get a good modem connection speed/quality between the two FXS ports on the o2 Box? How can I use this option with Asterisk once compiled and flashed? Currently my extensions.conf contains only

[lantiq1]
exten => 1002,1,Dial(TAPI/2,30,t)
[lantiq2]
exten => 1001,1,Dial(TAPI/1,30,t)

Thanks for any help! (Project outline at https://github.com/markostamcar/muzej.si/tree/master/dial-up/openwrt )

Edit 1: There also seems to be a "internal call" support using IFX_TAPI_MAP_PHONE_ADD which might remove the need for Asterisk and should disable any sound processing... however not sure how to enable this in a real life situation :slight_smile:

Edit 2: There is also a Pass-Through Mode (which just seems to be a bunch of suggested codec/echo/jitter config values) available if one Googles the following (including quote marks): "Pass-Through Mode" "tapi" "infineon"

Edit 3: Tried with lantiq.conf parameters set to Pass-Through Mode parameters from documentation with no improvement :frowning: