Fix SSH in Mac OS X by reinstalling Kerberos.framework

If you installed a recent OS X software update and SSH stops working with a segmentation fault (strangely, it works for some servers but not others), you need to get the latest Combo Update (often in the Featured Downloads section of Apple's site), mount the disk image, then open the .pkg file with Pacifist. Browse through the files in Pacifist to /System/Library/Frameworks, select Kerberos.framework and choose Install from the toolbar. After that SSH should work fine again.