# Advanced Behaviors

- [Register Additional Authenticators](/v4.5/symfony-bundle/advanced-behaviors/register-authenticators.md)
- [Debugging](/v4.5/symfony-bundle/advanced-behaviors/debugging.md)
- [User Verification](/v4.5/symfony-bundle/advanced-behaviors/user-verification.md)
- [Attestation and Metadata Statement](/v4.5/symfony-bundle/advanced-behaviors/attestation-and-metadata-statement.md)
- [Authenticator Selection Criteria](/v4.5/symfony-bundle/advanced-behaviors/authenticator-selection-criteria.md)
- [Authentication without username](/v4.5/symfony-bundle/advanced-behaviors/authentication-without-username.md)
- [Extensions](/v4.5/symfony-bundle/advanced-behaviors/extensions.md)
- [Token Binding](/v4.5/symfony-bundle/advanced-behaviors/token-binding.md)
- [Authenticator Counter](/v4.5/symfony-bundle/advanced-behaviors/authenticator-counter.md)
- [Dealing with “localhost”](/v4.5/symfony-bundle/advanced-behaviors/dealing-with-localhost.md)