The tale of open internet during placements in IITG

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Placement test going on for a company

Backstory:

I was the departmental placement coordinator for the Computer Science and Engineering department and I was a part of the placement team, it was the 30th of November 2016 and the placement season at IIT Guwahati was going to start from the next day early morning(i.e 1st Dec). Now the problem was there were going to be a lot of companies visiting the campus for recruitment at the same time and they all require access to the internet. In IITG, internet is provided by the Computer Center using squid proxy (HTTP/HTTPS) with authentication and it was not supported by all the applications. Though we have IITG Guest WIFI to which you can connect using a password and you wouldn’t require any kind of proxy. But it doesn’t have much coverage in the hostel where the placements are held. This created a problem for us because now we have to provide internet for these recruiters somehow, the problem was with nearly 7–10 companies in a slot, 3 slots a day, and 7–12 recruiters per company and a lot of chaos going around, it would be really tough to configure those many devices with proxy settings and sometimes you can’t even make many changes to company issued laptop’s settings, sometimes they use devices like blackberry and I did not know how to set proxy settings in it since I never used one. And it was a huge headache for us.

The Plan:

I got to know about this issue really late on 30th Nov evening that we need open internet without restrictions (No ports must be blocked) so that we didn’t have to configure any proxy settings on the recruiters laptops/mobiles. Now I had to figure out a way to make this happen. And this was the series of incidents that lead to the solution:

  • Now the scenario was I had a single public IP which was available in a certain port in the hostel main switch which had open internet access and I had to somehow make it available for all the recruiters.
  • Thought for a while and used the networks knowledge I learnt in the previous year course to solve this issue. First, I got a server from CBS (Campus Broadcasting System) since it has more than 1 interface.
  • I also had approx. 20 wifi routers which can be used. So I had to plan in such a way that the recruiters should only have to connect to the wifi and their systems should have internet access without any other configurations.
  • The plan itself it pretty straight forward. I have to somehow route all the traffic to and from wifi routers to the single IP which has open internet access.
  • So I configured the server from CBS such that it had 2 IPs on 2 different interfaces. One IP which has open internet access and the other IP to be on the hostel network. Now all I had to do is to IP forward the packets from one network to another and add some rules in iptables.
  • And I had to route traffic from all the wifi routers to this server which had hostel IP. This can be achieved by making the server IP the gateway address for these wifi routers.
  • WiFi routers → Server NIC(Ethernet card) with Hostel IP → IP Forwarding → NIC with Public IP → outside world
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The server.

Conclusion:

This is the point when I realized that having a clear understanding of the subject can help solving certain real world problems relatively easily. You should not only work hard, you should work smart too. At that point what grade I got in the networks course didn’t really matter, what mattered was how much knowledge did I gain out of it. Now that I worked on live video streaming I feel that this is a really small deal. But working in such kind of pressure and just trusting your knowledge and going forward with that plan and making it a success really made me happy.

Written by

Founder/CEO Hackrew | Security Researcher | Indian | Alumnus, IIT Guwahati

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