First, notice that you have an error
Warning: the RSA host key for '[server]:10400' differs from the key for the IP address...
That means that the server's public key does not match it's ip address. To resolve that, edit your ~/.ssh/known_hosts file and remove the entry for
You could do this with one command
ssh-keygen -R 192.168.1.40
Second there is a better way to connect to a server by using RSA keys instead of .ppk keys.
According to filext.com
The PPK file type is primarily associated with 'PuTTY'. PuTTY is a
terminal emulator application which can act as a client for the SSH,
Telnet, rlogin, and raw TCP computing protocols.
You didn't specify, but I am assuming that you wish to log into a linux web server from a Windows and a Mac computer simultaneously?
A better way to setup keys would be to take the public key of your ssh server, and place it into the known_hosts file of your Mac.
You could then setup pass wordless ssh by taking your Mac's public key and appending it to the authorized hosts file on the linux web server.
Here is how to copy your Mac's public key to the authorized hosts on the linux server in one command
cat ~/.ssh/id_rsa.pub | ssh user@machine "mkdir ~/.ssh; cat >> ~/.ssh/authorized_keys"