What

Network traffic can go in many directions, and there are many jargony ways to refer to them. Let’s define them.

Ingress Traffic is traffic that originates outside the local network that is transmitted to somewhere inside the local network. Remember ingress traffic is coming in.

Egress Traffic is traffic that originates inside the local network that is transmitted somewhere outside of the local network. Remember egress traffic is exiting the local network.

 INGRESS TRAFFIC EXAMPLE          EGRESS TRAFFIC EXAMPLE

         +-----+                          +-----+
         |     |                          |     |
     +---+     +------+               +---+     +------+
   +-+                |             +-+                |
 +-+   The Internet   ++          +-+   The Internet   ++
 |                   +-+          |                   +-+
 +-------------------+            +-------------------+

               V                                ^
               |                                ^
               |                                |
+----------------------+         +----------------------+
| Container    |       |         | Container    |       |
|              |       |         |              |       |
| +-------+    |       |         | +-------+    |       |
| |       |    |       |         | |       |    |       |
| | MyApp | <--+       |         | | MyApp | >--+       |
| |       |            |         | |       |            |
| +-------+            |         | +-------+            |
+----------------------+         +----------------------+

North/South traffic is any communication between two different networks. Both Ingress and Egress are examples of North/South traffic.

East/West traffic is any communication within one network.

                  EAST/WEST TRAFFIC EXAMPLE

+-------------------------------------------------------------+
| My Local Network                                            |
|                                                             |
|                                                             |
|                                                             |
| +----------------------+         +----------------------+   |
| | Container1           |         | Container2           |   |
| |                      |         |                      |   |
| | +-------+            |         | +-------+            |   |
| | |       |            |         | |       |            |   |
| | | MyApp | +----------------->  | | MyApp |            |   |
| | |   1   |            |         | |   2   |            |   |
| | +-------+            |         | +-------+            |   |
| +----------------------+         +----------------------+   |
|                                                             |
+-------------------------------------------------------------+

❓Questions

How would you use ingress, egress, north/south, and east/west to describe the following situations:

  • You visit neopets in your browser.
  • Your pair ssh-es onto your computer.
  • You set up a local netcat server and send traffic to it from your terminal.