What alternatives are there when SSH is being actively filtered?

From what I heard earlier today, https/ssl flows correctly through your borders.

You should hence check out Corkscrew.

Similarly to netcat, it's used to wrap ssh in https to allow the use of https proxies.

Another solution would be to use LSH which, by having a different signature than ssh, works from Iran as Siavash noted it in his message.

Based on a talk at the CCC conference - 28C3: How governments have tried to block Tor - the Tor Project has the best track record in this dynamic and challenging field, and it can be used for SSH. Innovative usage of Tor bridges is one of the latest developments. The 28C3 Tor talk is also on YouTube and the slides are at https://svn.torproject.org/svn/projects/presentations/slides-28c3.pdf

Note that using evasive methods that can be identified too easily can expose the user to yet more violations of their human rights and personal security. Be careful.

Update: Article 19 of the The Universal Declaration of Human Rights is relevant here:

• Article 19: Everyone has the right to freedom of opinion and expression; this right includes freedom to hold opinions without interference and to seek, receive and impart information and ideas through any media and regardless of frontiers.

If you have unfiltered https you can do something like AjaxTerm or any other AJAX or HTML5 based terminal emulator running on a protected site within a webserver that can either connect to a local ssh daemon or in certain cases to remote ones on other interfaces of your machine.

Another option (tough a bit obscure) if you have ICMP to your box would be to run TCP/IP on top of ICMP if that is open. See here.