# ELB Listeners Part 1

* Before you start using Elastic Load Balancing, you **must configure one or more listeners for your ELB.**\\

* A **listener is a process that checks for connection requests**.\\

* It is **configured with a protocol and a port for front-end (client to load balancer) connections**, and a **protocol and a port for back-end (load balancer to back-end instance) connections**.\\

* Elastic Load Balancing **supports the following protocols:**
  * **HTTP**
  * **HTTPS (secure HTTP)**
  * **TCP**
  * **SSL (secure TCP)**\\

* The **HTTPS protocol uses the SSL protocol to establish secure connections over the HTTP layer**.

* You can also **use the SSL protocol to establish secure connections over the TCP layer**.\\

* If the **front-end connection uses TCP or SSL, then your back-end connections can use either TCP or SSL**.

* If the **front-end connection uses HTTP or HTTPS, then your back-end connections can use either HTTP or HTTPS**.

## Create an HTTPS listener for your ALB <a href="#create-https-listener" id="create-https-listener"></a>

* You **can create an HTTPS listener, which uses encrypted connections (also known as SSL offload)**.\\

* This feature **enables traffic encryption between your load balancer and the clients that initiate SSL or TLS sessions**.\\

* To use an HTTPS listener, you **must deploy at least one SSL/TLS server certificate on your load balancer**.\\

* The load balancer **uses a server certificate to terminate the front-end connection** and then **decrypt requests from clients before sending them to the targets**.\\

* The **load balancer requires X.509 certificates (SSL/TLS server certificates)**.\\

* **Certificates are a digital form of identification issued by a certificate authority (CA)**.
