MacOS – How to ssh in to a blowfish-based server from MacOS Sierra

command linecompatibilitymacosssh

We've got some embedded devices that we need to ssh in to sometimes in order to administer, but the devices' ssh server only supports the "blowfish" cypher.

This has been working okay, except that for MacOS 10.12 Sierra, Apple has removed support for the Blowfish algorithm, meaning that MacOS's built-in command-line ssh client will no longer connect to this device.

Given that we can't (easily) upgrade the embedded device to use a different cypher, what would be our best approach to connecting to this device from a Sierra-based Mac? Is there some other ssh client we could use instead, or some way to re-enable blowfish support for the built-in client?

Best Answer

Manual page for ssh explains the -c switch, which is used for the cipher specification:

ssh -c blowfish-cbc your_host

should do the job.