Quozl's Open Source

IP over serial on Raspberry Pi

Electronics

How to set up IP over 3.3V serial between a Raspberry Pi and a host computer running Linux.

Prepare the host computer;

install the ppp package
```
sudo apt install --yes ppp
```
attach a USB to 3.3V serial adapter to the appropriate GPIO pins, and plug it in to the computer,
identify the device, let's assume it appears as /dev/ttyUSB0,
run as root
```
pppd nodetach debug noauth nocrtscts local passive /dev/ttyUSB0 115200 lcp-max-configure 10000
```
(this will repeatedly try to establish a connection, because the LCP configure-request transmission count is set very high).

Prepare the Raspberry Pi;

install the ppp package
```
sudo apt install --yes ppp
```

add two lines to /etc/rc.local before the exit

systemctl stop serial-getty@ttyAMA0.service
pppd updetach debug nocrtscts noauth local 10.1.0.1:10.1.0.2 /dev/ttyAMA0 115200

reboot

The link will be established, and you can ping or SSH to 10.1.0.1.

Use different addresses if required.

What it looks like on the host computer

using channel 9
Using interface ppp0
Connect: ppp0 <--> /dev/ttyUSB0
sent [LCP ConfReq id=0x1 <asyncmap 0x0> <magic 0x25b9b80a> <pcomp> <accomp>]
sent [LCP ConfReq id=0x1 <asyncmap 0x0> <magic 0x25b9b80a> <pcomp> <accomp>]
sent [LCP ConfReq id=0x1 <asyncmap 0x0> <magic 0x25b9b80a> <pcomp> <accomp>]
sent [LCP ConfReq id=0x1 <asyncmap 0x0> <magic 0x25b9b80a> <pcomp> <accomp>]
sent [LCP ConfReq id=0x1 <asyncmap 0x0> <magic 0x25b9b80a> <pcomp> <accomp>]
sent [LCP ConfReq id=0x1 <asyncmap 0x0> <magic 0x25b9b80a> <pcomp> <accomp>]
sent [LCP ConfReq id=0x1 <asyncmap 0x0> <magic 0x25b9b80a> <pcomp> <accomp>]
sent [LCP ConfReq id=0x1 <asyncmap 0x0> <magic 0x25b9b80a> <pcomp> <accomp>]
sent [LCP ConfReq id=0x1 <asyncmap 0x0> <magic 0x25b9b80a> <pcomp> <accomp>]
sent [LCP ConfReq id=0x1 <asyncmap 0x0> <magic 0x25b9b80a> <pcomp> <accomp>]
sent [LCP ConfReq id=0x1 <asyncmap 0x0> <magic 0x25b9b80a> <pcomp> <accomp>]
sent [LCP ConfReq id=0x1 <asyncmap 0x0> <magic 0x25b9b80a> <pcomp> <accomp>]
sent [LCP ConfReq id=0x1 <asyncmap 0x0> <magic 0x25b9b80a> <pcomp> <accomp>]
sent [LCP ConfReq id=0x1 <asyncmap 0x0> <magic 0x25b9b80a> <pcomp> <accomp>]
sent [LCP ConfReq id=0x1 <asyncmap 0x0> <magic 0x25b9b80a> <pcomp> <accomp>]
sent [LCP ConfReq id=0x1 <asyncmap 0x0> <magic 0x25b9b80a> <pcomp> <accomp>]
rcvd [LCP ConfReq id=0x1 <asyncmap 0x0> <magic 0xa67760f> <pcomp> <accomp>]
sent [LCP ConfAck id=0x1 <asyncmap 0x0> <magic 0xa67760f> <pcomp> <accomp>]
rcvd [LCP ConfAck id=0x1 <asyncmap 0x0> <magic 0x25b9b80a> <pcomp> <accomp>]
sent [LCP EchoReq id=0x0 magic=0x25b9b80a]
sent [CCP ConfReq id=0x1 <deflate 15> <deflate(old#) 15> <bsd v1 15>]
sent [IPCP ConfReq id=0x1 <compress VJ 0f 01> <addr 0.0.0.0>]
rcvd [LCP ConfAck id=0x1 <asyncmap 0x0> <magic 0x25b9b80a> <pcomp> <accomp>]
rcvd [LCP ConfAck id=0x1 <asyncmap 0x0> <magic 0x25b9b80a> <pcomp> <accomp>]
rcvd [LCP ConfAck id=0x1 <asyncmap 0x0> <magic 0x25b9b80a> <pcomp> <accomp>]
rcvd [LCP ConfAck id=0x1 <asyncmap 0x0> <magic 0x25b9b80a> <pcomp> <accomp>]
rcvd [LCP ConfAck id=0x1 <asyncmap 0x0> <magic 0x25b9b80a> <pcomp> <accomp>]
rcvd [LCP ConfAck id=0x1 <asyncmap 0x0> <magic 0x25b9b80a> <pcomp> <accomp>]
rcvd [LCP ConfAck id=0x1 <asyncmap 0x0> <magic 0x25b9b80a> <pcomp> <accomp>]
rcvd [LCP ConfAck id=0x1 <asyncmap 0x0> <magic 0x25b9b80a> <pcomp> <accomp>]
rcvd [LCP EchoReq id=0x0 magic=0xa67760f]
sent [LCP EchoRep id=0x0 magic=0x25b9b80a]
rcvd [CCP ConfReq id=0x1 <deflate 15> <deflate(old#) 15> <bsd v1 15>]
sent [CCP ConfAck id=0x1 <deflate 15> <deflate(old#) 15> <bsd v1 15>]
rcvd [IPCP ConfReq id=0x1 <compress VJ 0f 01> <addr 10.1.0.1>]
sent [IPCP ConfAck id=0x1 <compress VJ 0f 01> <addr 10.1.0.1>]
rcvd [LCP EchoRep id=0x0 magic=0xa67760f]
rcvd [CCP ConfAck id=0x1 <deflate 15> <deflate(old#) 15> <bsd v1 15>]
Deflate (15) compression enabled
rcvd [IPCP ConfNak id=0x1 <addr 10.1.0.2>]
sent [IPCP ConfReq id=0x2 <compress VJ 0f 01> <addr 10.1.0.2>]
rcvd [IPCP ConfAck id=0x2 <compress VJ 0f 01> <addr 10.1.0.2>]
local  IP address 10.1.0.2
remote IP address 10.1.0.1
Script /etc/ppp/ip-up started (pid 80399)
Script /etc/ppp/ip-up finished (pid 80399), status = 0x0

(25 September 2022)

quozl@us.netrek.org