File sharing is as ubiquitous at Columbia as almost any other university. File sharing of copyrighted content is illegal. However, you are of course allowed to share copyright-free content.
File sharing methods
File sharing kicked off through computer programs like Napster and Kazaa. These were either shut down or became clogged up with falsely named files. Many students then turned to DC++, but this was shut down by AcIS. After that, people turned to i2hub, which was based on the DC++ protocol. The i2hub network ran on the high-speed Abilene Network, which was created by the Internet2 consortium. This also restricted the network to university students and therefore there were few falsely named files. The most popular P2P program is now Limewire.
BitTorrent is a revolutionary file sharing protocol whereby files are split into much smaller components. All the users sharing a file collaborate to share these components as rapidly as possible. This makes BitTorrent an excellent way to rapidly download movies, music, and other large file-size content. When sharing a file using BitTorrent, the user's IP address is visible to all the other users sharing that file. Many students get caught violating copyrights when an organization acting on behalf of the RIAA or MPAA connects to the file and makes a note of all the IP addresses.
Columbia.edu email address holders are able to use Ruckus to download a large selection of copyrighted files perfectly legitimately. However, the selection of songs is rather limited. Ruckus only works on Windows computers, not Macs. And there are heavy DRM restrictions. For example, you can't play Ruckus files on your portable audio device.
Other file acquisition methods
These methods do not involve uploading files and are therefore not file sharing methods. That said, even just downloading copyrighted files is illegal. The only difference is that it's harder to trace and harder to prosecute.
While movies and music are the most commonly pirated types of media at Columbia, textbook PDFs are often even more valuable, considering the rising price of textbooks. As of early 2016, the most common DDL (direct download) sites for downloading textbooks are:
These URLs are subject to change, though a quick google will usually take you to a subreddit or Hacker News thread with the most up to date one.
Almost every node on the Columbia network is restricted to downloading 2000 MB per hour and uploading 700 MB per hour. A 700 MB movie would take 45 minutes to download going at maximum speed on the Columbia network, or about 2.5 hours at throttled speed. Users who exceed the above limits are restricted to a severely throttled bandwidth for between 20 minutes and 4 hours depending on how much they went over the limits. The throttled bandwidth is extremely slow; only fast enough for slowly surfing basic web pages. Thus, if you plan to download a large file, you may want to limit your download speed to 570 KB/s and your upload speed to 200 KB/s.
Bandwidth limits are currently only applied from 10am to midnight. So from midnight to 10am, you can download at unrestricted speeds, up to four times faster than the restricted speeds mentioned above. In practical terms, this means you can download up to 3.5 GB per hour, equivalent to about 1 MB/s. You can also upload at similar speeds.
In late 2008, the RIAA and MPAA ceased their antipiracy strategy of suing individual users, partially because braver universities announced they would no longer hand over student information voluntarily. The myth that copyright organizations still pursue lone filesharers persists, with help from harshly-worded CUIT antipiracy posters in most computer labs and residence halls.
Although large rightsholder organizations no longer pursue students, CUIT still takes it upon itself to penalize filesharers.
Organizations like the RIAA and MPAA hire specialized detection firms to track down students who illegally upload and download files. Such firms log on to file sharing networks and BitTorrent, and connect to users on these networks to obtain their IP addresses.
The firm then sends letters to Columbia to forward to the violating IP addresses. IP addresses on the Columbia residence halls network are static and can be tied to a particular user (except for the public network jacks). CUIT is therefore able to identify the user and pass on the letter.
If the user was logged on in a computer lab, CUIT compares the IP to a time log and can therefore still identify the particular user.
CUIT is less aggressive about pursuing filesharers in UAH buildings or offices connected to the Columbia network, although they still do on occasion.
Some file sharers try to avoid detection by connecting to file-sharing networks via another computer (a proxy). The user can then connect to file-sharing networks and use the internet as normal, except that the IP address by which their computer is visible to these networks is that of the other computer (the proxy). This way, if the RIAA or MPAA or some other organization wants to make a claim, they will address it to the proxy rather than the end-user file-sharer. This is useful if the proxy is in a jurisdiction with lax copyright laws like Sweden. By connecting to file-sharing networks via a Swedish proxy, it is almost impossible for any such organization mentioned above to make a claim against the user.
Some file sharers also avoid detection on the Columbia wifi network by changing or "spoofing" their MAC address once their previous MAC address has been identified as violating copyright. It is unclear whether this is legal. However, students who do it generally don't care because there is no easy way for CUIT to learn whether your MAC address is genuine or spoofed. In 2011, an anonymous Columbia redditor released an initial guide to doing so 
Others use public network jacks in the libraries and classrooms. These cannot be traced to individual users unless CUIT tries to match UNI login records (eg, for Cubmail, Courseworks, or SSOL) with connection records.
A foolproof way to avoid getting caught is to go to somewhere with free Wi-Fi such as Starbucks or Uni Cafe and then torrent off of their network.
Columbia blocks file sharers from accessing its network upon receiving a notice from the RIAA or MPAA. Students are generally able to reactivate their network access upon affirming that they do not hold any content in violation of copyrights, and that they promise not to illegally share files in the future. Columbia does not monitor this promise. If Columbia receives a second notice from the RIAA or MPAA, the student's internet access may be permanently disabled, and the student is subjected to Dean's Discipline.
Effects on Columbia students
- Columbia gets a few hundred DMCA notices per year.
- The RIAA has so far sued 47 Columbia file sharers, of whom 39 settled out of court.
- 39 of the 47 lawsuits arose from RIAA targetting of i2hub.
- On Wednesday 21 March 2007, a further 20 students were issued threats of lawsuits by the RIAA unless they settle.
- Some students have formed a club called Free Culture at Columbia to protest against copyright and the RIAA and MPAA's legal actions.
- Columbia was recently honored by the MPAA  as the #1 school for movie piracy. However, Columbia was snubbed by the RIAA and did not even break the top 25 worst offenders list.