Yes, of course - but only if you use Message security (rather than transport security). Define your binding configuration like so:
<netTcpBinding>
<binding name="UserNameSecurity">
<security mode="Message">
<message clientCredentialType="UserName"/>
</security>
</binding>
</netTcpBinding>
and then reference that binding configuration in your endpoints (on server and client):
<endpoint address="....."
binding="netTcpBinding"
bindingConfiguration="UserNameSecurity"
contract="IMyService" />
Marc
UPDATE:
Ah, yes, on the server-side, you'll need a certificate to authenicate the service to the client calling it, and it's also used to encrypt+sign the messages. That's on the server only - clients need not install anything.
Configuration:
<behavoirs>
<serviceBehavior>
<behavior name="ServerInternet">
<serviceCredentials>
<serviceCertificate
findValue="MyServiceCertificate"
storeLocation="LocalMachine"
storeName="My"
x509FindType="FindBySubjectName" />
</serviceCredentials>
</behavoir>
</serviceBehavior>
</behavoirs>
<services>
<service name="MyServiceInternet"
behaviorConfiguration="ServerInternet">
....
</service>
</services>
Make sure to install your server's certificate into the "Local Machine" folder on your server, under the "subject name" that you specify in your config.