Found this post on serverfault about this. I attempted to set the limit_conn limit to 1 but its still allowing more than one login. Trying to limit each user to a single session.

limit_conn_zone $remote_user zone=limit:10m;

server {
listen 80;
listen [::]:80;
server_name localhost;
auth_basic "Restricted Content";
auth_basic_user_file /etc/nginx/.htpasswd;
limit_conn limit 1;

#charset koi8-r;
#access_log /var/log/nginx/host.access.log main;

location / {
root /usr/share/nginx/html;
index index.html index.htm;
}


https://serverfault.com/questions/993936/nginx-restrict-number-of-connections-per-basic-auth-user#:~:text=1%20Answer&text=Now%20each%20user%20can%20open%20no%20more%20than%205%20simultaneous%20connections.

Just need to find away to limit concurrent sessions by user whether that's by limiting user access using an IP. So the each user can only access that system using from one public ip. Trying to find something in the documentation maybe I'm wording it wrong.