We generate certificates that are intended to be used for server authentication in a couple of places:

- `bin/elasticsearch-certutil http` command  ( See `CertGenUtils.generateSignedCertificate` in `HttpCertificateCommand` )
- TLS auto-configuraion for node startup ( see [`AutoConfigureNode`](https://github.com/elastic/elasticsearch/blob/814f7f9f52cb8c05db6465b9bfc818ea5d76c575/x-pack/plugin/security/cli/src/main/java/org/elasticsearch/xpack/security/cli/AutoConfigureNode.java#L454) )

In these cases we know that the certificate is meant to be used for server authentication, so we can set Extended Key Usage extension to `1.3.6.1.5.5.7.3.1`
x-pack/plugin/security/cli/src/main/java/org/elasticsearch/xpack/security/cli/HttpCertificateCommand.java
break;
            } else {
                dnsNames.clear();
            }
        }
        printHeader("Which IP addresses will be used to connect to " + nodeDescription + "?", terminal);
        terminal.println("If your clients will ever connect to your nodes by numeric IP address, then you");
        terminal.println("can list these as valid IP \"Subject Alternative Name\" (SAN) fields in your");
        terminal.println("certificate.");
        terminal.println("");
        terminal.println("If you do not have fixed IP addresses, or not wish to support direct IP access");
        terminal.println("to your cluster then you can just press <ENTER> to skip this step.");
        final List<String> ipNames = new ArrayList<>();
        while (true) {
            terminal.println("");
            terminal.println("Enter all the IP addresses that you need, one per line.");
            terminal.println("When you are done, press <ENTER> once more to move on to the next step.");
            terminal.println("");
            ipNames.addAll(readMultiLineInput(terminal, this::validateIpAddress));
            if (ipNames.isEmpty()) {
                terminal.println(Terminal.Verbosity.SILENT, "You did not enter any IP addresses.");
            } else {
                terminal.println(Terminal.Verbosity.SILENT, "You entered the following IP addresses.");
                terminal.println(Terminal.Verbosity.SILENT, "");
                ipNames.forEach(s -> terminal.println(Terminal.Verbosity.SILENT, " - " + s));
            }
            terminal.println("");
            if (terminal.promptYesNo("Is this correct", true)) {
                break;
            } else {