Konqueror barfs on an sftp:// url with this error:

	"Additional Information: The host key for this server was not found, but another
	type of key exists. An attacker might change the default server key to confuse
	your client into thinking the key does not exist. Please contact your system

but you can ssh and sftp to the host normally via the command line.

The issue is that Konqueror uses a different SSH library that may not support
ECDSA keys yet on your system. Upgrade if possible. If you can't upgrade, you
can add the server's RSA key to your known_hosts file to keep Konqueror happy:

ssh to the server in question

on the remote server, run:

$ ssh-keyscan [ -p<port_number> ] -t rsa localhost

This will return something like this:

# localhost SSH-2.0-OpenSSH_6.6.1p1 Ubuntu-2ubuntu2
localhost ssh-rsa AAAAagyag9bhghgahaGAGGGASgdgs9D...

Copy that long second line beginning with 'localhost' into your
~/.ssh/known_hosts file, and replace 'localhost' with the server name you're
using in konqueror.

Try konqueror again.

If you're using a nonstandard ssh port and Konqueror still doesn't work, edit
your known_hosts file again and change the hostname to the IP address of the
server and the port number, in this format:

If you now get "Additional Information: Authentication failed." because you use
ECDSA keys to authenticate, generate an RSA identity key and add it to
authorized_keys on the remote server. If necessary, modify .ssh/config for the
host to tell ssh to use that key.

If you can connect but still encounter random hanging / "authentication failed"
only intermittently, try adding your username and the port number to the sftp
URL, and starting konqueror with:

KDE_FORK_SLAVES=true konqueror