Deployment with Docker

Ephemeral ports

If you aren't familiar with ephemeral ports, they are the port numbers that all outbound connections get assigned if the originating port is not explicitly specified on the connection, which is the vast majority of them. For example, if you do any kind of outbound HTTP request with almost every client library, you will most likely have one of these ephemeral ports assigned as the return communication port for your connection.

To see some sample ephemeral port usage on your machine, you can use netstat:

$ netstat -an | grep ESTABLISHEDtcp        0      0 192.168.56.101:46496     <redacted>:443      ESTABLISHEDtcp        0      0 192.168.56.101:45512     <redacted>:443      ESTABLISHEDtcp        0      0 192.168.56.101:42014     <redacted>:443      ESTABLISHED<snip>tcp 0 0 192.168.56.101:45984 ...