a small trick: automatically sign in SRUN3000 with OpenWRT

I. Background

Tianjin University has just implemented SRUN3000 authentication program, which restricts internet access without signed in.

It is very inconvenient to sign in every single time. So i decided to do something.

In this case, I have a router with OpenWRT running.

(btw: most tp-link wireless router could manage to update to openwrt firmware if you are willing to try this out)


II. Solution

OpenWRT provides hotplug2 feature to trigger scripts while interface state changed.

Save this script to /etc/hotplug.d/iface/30-srun:

#!/bin/sh
[ "$ACTION" = ifup ] || exit 0
[ "$INTERFACE" = wan ] || exit 0

# delay for 2 second
sleep 2

# nc to create a http post request
nc g.tju.edu.cn 80 < /tmp/post_login

And chmod it with x access.

Next step, save this datadump to /tmp/post_login:

GET /cgi-bin/do_login HTTP/1.1

Host: g.tju.edu.cn

Content-Type: application/x-www-form-urlencoded

Content-Length: 77

username=ID&password=PASSWORD&drop=0&type=1&n=100&force=true

replace ID with your account, PASSWORD with Substring(8, 16) of the md5 hash of your password. i.e. 123456 is 49ba59abbe56e057f. 

And 77 should be the total length of these parameters (username=ID&password=PASSWORD&drop=0&type=1&n=100&force=true).

--- EOF --