buy Certificate for ASA annyconnect to skip the "untrusted connection" message

[Dr.X]

hi 

I have my ASA 5505 with any connect for VPN

but each time  i connect it prompt me for popup that says the connection is "untrusted" and i have  press and accept the connection .

the question here 

can i buy a certificate online and install it on the ASA so that i don't see the popup that say the connect is not secure ??

if so

will it something done on the ASA only ?

or need to add certs on the clients devices too ??????

kind regards

[Karsten Iwen]

You have to:

1. Generate an Certificate Signing Request (CSR) on your ASA, which is done under Certificates -> Identity Certificates in ASDM. Generate a new keypair with 2048 Bit for that.
2. Go to the CA of your choice (for cheap certificates I use sslmarket.de, .us, .co.uk ...) and upload your signing request.
3. Receive the certificate and import it to the ASA.
4. Assign this certificate (Trustpoint) to your outside interface.
5. On the clients, nothing has to be done.