session: put style as line number to ssh session environment variable

[Blueve]

Overview

The style field in authctx were assigned in auth*.c

ssh username:style@hostname

The origin username is username:style, but the sshd will split it by : and then use username for authentication and put the style to authctx's style field.

This patch will take advantage of the style field for SONiC Console Switch reverse SSH feature:

ssh <username>:<line>@<host>

Build & Installation Guide

Build source code

Clone code and enter the source folder.

mkdir build && cd build
../configure --with-pam --with-md5-passwords
make

Installation

If you has installed a ssh-server on your device, find it path by using whereis sshd.

Then stop sshd.

sudo service ssh stop

Copy your built sshd to the path you find in previous step.

sudo cp sshd <path_to_origin_sshd>

Start sshd.

sudo service ssh start

Test & Verification

ssh admin:21@localhost
admin@localhost: echo $SSH_TARGET_LINE
21

Progress

• Test on Ubuntu WSL
• Test on Azure Ubuntu VM
• Test on SONiC VS
• Test on SONiC Physical DUT