Monday, May 14, 2012

Mosh - better remote shell

In this age of 3d accelerated desktops and all that fancy stuff, one does not expect practical innovation happening in the remote terminal emulation area. But it has just happened. It is called Mosh, a shorthand for "Mobile Shell".

What does it do better than ssh we have learned to love?

  • Less lag! Being UDP based, it is not prone to TCP congestion effects. Considering that voip, games and everything else latency critical has been UDP based, it is (almost) surprising that it wasn't done for interactive terminals before...
  • Even less lag! Mosh provides local echo and line editing when the other side is not being responsive. To do this, mosh actually becomes a terminal emulator of it's own. This stuff is sweet on unstable 3G and conference wifi networks.
  • Survives suspending. Resume your laptop and *bam* all your remote mutt and vim editors are still there instead of the "connection reset" you get from ssh.
  • Roaming. Got another IP? Moved from wifi to ethernet to 3G? your sessions are still open! Another thing a TCP based protocol couldn't do easily...
It doesn't replace ssh, as it still borrows authentication from ssh. But that's cool, as you can keep your ssh authorized keys.

Available in Debian unstable,testing and Backports today, and many other systems as well. Hopefully an Android client comes available soon, as the above mentioned advantages seem really tailored for android like mobile systems.

Caveat: This is new stuff, and thus hasn't quite been proven to be secure.

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