Ali Jahanshahi, a young, tech-savvy British-Iranian, quit his job selling computers to come to New York with the ambitious goal of ousting Iranian President Mahmoud Ahmadinejad.

More than just protesting Ahmadinejad's presence at the U.N. General Assembly this week, Jahanshahi said he came to trade know-how with other young Iranians who are using Internet hacktivism to send messages, videos and information to opposition sympathizers in Iran.

Iran's government tries to keep protesters from organizing online but we use tools to stay ahead of them, Jahanshahi, 20, said at a protest outside the United Nations. We post videos, tweet messages and set up sites to help people in Iran organize.

Since anti-government protests erupted after Iran's disputed June 12 elections, the government has slowed Internet speeds, shut down opposition websites and arrested opposition members who try to organize online.

Journalists inside Iran have been banned from attending protests, but that has not kept footage of anti-Ahmadinejad gatherings from reaching the Internet.

A low-fidelity cellphone video of the bloody death of 16 year-old student Neda Soltani at a protest in June, allegedly at the hands of Iranian forces, has been viewed millions of times online.

Hundreds of Iranians converged near the United Nations this week to protest Ahmadinejad's visit.

In past years, such protests were attended mostly by older Iranians, some in exile since the 1979 Islamic Revolution.

This time, students and young people abounded, equipped with IPhones, Twitter, Facebook and YouTube accounts to communicate with like-minded youth in Iran.

Many said they were encouraged by new protests in Iran last Friday, when thousands took to the streets after a two-month lull when such gatherings slowed amid the crackdown.

Ahmadinejad is not Iran's legitimate president and he's got to go, but you will never see that view on television in Iran, said Aryan Khalili, 22, a criminal justice student.

Everything we do here is put on YouTube and file-sharing sites, so people in Iran know we're with them.

Jahanshahi said he has designed anti-Ahmadinejad websites in Farsi that go live for a day or two in Iran, garnering hundreds or thousands of hits before they are shut. Then, he said, he shuffles the contents to new sites.

Jahanshahi said he and his cohort of Iranian expatriates see themselves as key helpers to Iran's resistance movement.

Nobody can take down Iran's government by protesting in New York, said Omid Omidvar, an anti-Ahmadinejad television producer who was videotaping protests to beam into Iran.

It has to happen inside Iran, but we play a supporting role, he said.

(Editing by Alan Elsner and Ellen Wulfhorst)