Secure Consul¶

For security reasons, we strongly recommend configuring the TLS encryption.

Caution - firewall

Due to everyone who can access the Consul Web interface via port 8500 can change the configuration including the user authorization, we strongly recommend protecting Consul via firewall. Only the Output Engine servers and maybe the workstations of the system administrators should have access to Consul.

Hint - TLS encryption for required software

Please also refer to the following documentations regarding TLS encryption:

Configure the TLS Encryption¶

The connection to Consul is secured by the TLS certificate located in the /opt/seal/etc/tls directory. That means that after you have replaced the self-signed certificate enclosed in delivery by your own certificate in Secure the Output Engine Services the connection to Consul has already been secured.

Configure the TLS Encryption in a Cluster¶

If you are running PLOSSYS Output Engine in a cluster, execute the configuration steps above on all Output Engine servers.

Config a Consul Key in a Cluster¶

For how to configure Consul in a cluster, refer to Configure Consul in a Cluster.

The communication between the Consul instances in a cluster is encrypted symmetrically. A pre-shared key is installed.

Caution - security gap

Using the pre-installed key in a productive system is a serious security gap.

Show the Installed Keys¶

This is how you display all keys known to the Consul cluster:

Open a command line. Set the following environment variables (only on one server in case of a cluster):
```
export CONSUL_HTTP_SSL=true
export CONSUL_HTTP_SSL_VERIFY=false
```
Change to the directory of the Consul program:
```
cd /opt/seal/seal-consul-agent
```
List the installed keys:
```
./consul keyring -list
```
Hint - active key

The active key is highlighted. GfTiHCQsAMdYyUKN+BYhMw== is the default key set during the installation.

Replace the Key¶

This is how you replace the key:

Open a command line. Set the following environment variables (only on one server in case of a cluster):
```
export CONSUL_HTTP_SSL=true
export CONSUL_HTTP_SSL_VERIFY=false
```
Change to the directory of the Consul program:
```
cd /opt/seal/seal-consul-agent
```
Create a new symmetric key:
```
./consul keygen
```
The new key <new_key> is displayed.
Distribute the new key in the Consul cluster:
```
./consul keyring -install <new_key>
```
Activate the new key:
```
./consul keyring -use <new_key>
```
Delete the old key:
```
./consul keyring -remove <old_key>
```

Specify a CA Certificate (Unnecessary in Most Cases)¶

If a CA certificate has been specified, Consul requires a client certificate from each client, that means from all Output Engine services. This would require corresponding properties of the certificate and would be a high effort. A complete explanation of how to use client certificates is beyond the scope of this documentation.

For the rare other cases, this is how you configure a CA certificate with Consul:

Open the Consul configuration file on the Output Engine server:
```
/opt/seal/etc/consul.json
```
Insert the following lines in the first level, for example after the first opening bracket:
```
{
  "ca_file": "/opt/seal/etc/tls/ca.pem",
  "verify_outgoing": true,
...
}
```
Caution - JSON structure

Pay attention to keep the JSON structure in the configuration file! For further information, refer to http://json.org/json-de.html.
Save the configuration file.
Restart the following service:
- seal-consul-agent

Configure ACL¶

Literature - Consul documentation by HashiCorp

For an in-depth documentation refer to the Consul documentation by its developer HashiCorp, especially the section about ACL parameters.

Consul comes without ACL (Access Control List) configuration. This is how you configure ACL:

Stop PLOSSYS 5 completely using the --full parameter (on every server in case of a cluster).
Open the Consul configuration file on the PLOSSYS 5 server (on every server in case of a cluster):
```
/opt/seal/etc/consul.json
```

Insert the following lines in the first level, for example, after the first opening bracket (on every server in case of a cluster):

{
  "acl": {
    "enabled": true,
    "default_policy": "deny",
    "enable_token_persistence": true
  },
...
}

Start the following service (on every server in case of a cluster):
- seal-consul-agent
Open a command line. Set the following environment variables (only on one server in case of a cluster):
```
export CONSUL_HTTP_SSL=true
export CONSUL_HTTP_SSL_VERIFY=false
```
Change to the directory of the Consul program (only on one server in case of a cluster):
```
cd /opt/seal/seal-consul-agent
```

Execute ACL bootstrap (only on one server in case of a cluster):

./consul acl bootstrap

This results in an output like this:

AccessorID:       770956ae-f0bf-db1d-0dc0-c802b9fdea3a
SecretID:         145d39a6-1366-7e3b-496e-fd2f2ea6ae23
Description:      Bootstrap Token (Global Management)
Local:            false
Create Time:      2022-01-18 14:33:38.1674571 +0100 CET
Policies:         00000000-0000-0000-0000-000000000001 - global-management

Take a note of the SecretID of this ACL Bootstrap token.

Open the Consul user interface, select Tokens in the sidebar menu and click Log in on the top right (only on one server in case of a cluster):

Hint - access to Web interface

Every administrator who wants to change the PLOSSYS 5 configuration has do this in his browser. Otherwise, he will no longer be able to access the keys and values.
Enter the SecretID of the ACL Bootstrap token (in the example above, 145d39a6-1366-7e3b-496e-fd2f2ea6ae23) (only on one server in case of a cluster):
In the sidebar menu, change to Key/Value. Edit or create the dc/home/env/service/any/tag/any/CONSUL_TOKEN key. Set the SecretID of the ACL Bootstrap token (in this example, 145d39a6-1366-7e3b-496e-fd2f2ea6ae23) as the value of the key. (Do this only on one server in case of a cluster.)
Open the envconsul configuration file on the PLOSSYS 5 server (on every server in case of a cluster):
```
/opt/seal/etc/envconsul.json
```

Change the value of consul.token to the SecretID of the ACL Bootstrap token (in this example, 145d39a6-1366-7e3b-496e-fd2f2ea6ae23) (on every server in case of a cluster):

{
  "consul": {
    "address": "127.0.0.1:8500",
    "ssl": {
      "enabled": true,
      "verify": false
    },
    "token": "145d39a6-1366-7e3b-496e-fd2f2ea6ae23",
    "retry": {
      "attempts": 0
    }
  },
  "sanitize": true,
  "upcase": true,
  "vault": {
    "renew_token": false
  }
}

Restart the following service (on every server in case of a cluster):
- seal-consul-agent
To enable the services to make DNS requests create the dns-request-policy.hcl file in any directory with the following content (only on one server in case of a cluster):
```
node_prefix "" {
  policy = "read"
}
service_prefix "" {
  policy = "read"
}
query_prefix "" {
  policy = "read"
}
```

Execute the following command to create the policy for DNS requests, using the SecretID of the ACL Bootstrap token as token (in this example, 145d39a6-1366-7e3b-496e-fd2f2ea6ae23) (only on one server in case of a cluster):

./consul acl policy create -name "dns-requests" -rules @<arbitrary directory>/dns-request-policy.hcl -token 145d39a6-1366-7e3b-496e-fd2f2ea6ae23

This results in an output like this:

ID:           4e9cbd04-f18c-237b-6357-e5f6f405b74b
Name:         dns-requests
Description:
Datacenters:
Rules:
node_prefix "" {
  policy = "read"
}
service_prefix "" {
  policy = "read"
}
query_prefix "" {
  policy = "read"
}

Execute the following command to create the token for DNS requests, using the SecretID of the ACL Bootstrap token as token (in the example above, 145d39a6-1366-7e3b-496e-fd2f2ea6ae23) (only on one server in case of a cluster):

./consul acl token create -description "Token for DNS Requests" -policy-name dns-requests -token 145d39a6-1366-7e3b-496e-fd2f2ea6ae23

This results in an output like this:

AccessorID:       31dee823-61b7-a8ca-fec1-9103ea601a15
SecretID:         9e3f8b90-1c48-1899-8fed-55c94dab6016
Description:      Token for DNS Requests
Local:            false
Create Time:      2022-01-31 14:08:31.5254338 +0100 CET
Policies:
   4e9cbd04-f18c-237b-6357-e5f6f405b74b - dns-requests

Take a note of the SecretID of this ACL token.

Execute the following command to set the default token (only on one server in case of a cluster). Provide
- the SecretID of the ACL Bootstrap token with the -token parameter (in this example, 145d39a6-1366-7e3b-496e-fd2f2ea6ae23) and
- the SecretID of the newly created ACL token as the string at the end (in this example, 9e3f8b90-1c48-1899-8fed-55c94dab6016).
```
./consul acl set-agent-token -token 145d39a6-1366-7e3b-496e-fd2f2ea6ae23 default "9e3f8b90-1c48-1899-8fed-55c94dab6016"
```
This results in an output like this:
```
ACL token "default" set successfully
```
Execute the following command (only on one server in case of a cluster) to set the agent token. Provide the SecretID of the ACL Bootstrap token with the -token parameter and as the string at the end (in this example, 145d39a6-1366-7e3b-496e-fd2f2ea6ae23):
```
./consul acl set-agent-token -token 145d39a6-1366-7e3b-496e-fd2f2ea6ae23 agent "145d39a6-1366-7e3b-496e-fd2f2ea6ae23"
```
This results in an output like this:
```
ACL token "agent" set successfully
```
Start PLOSSYS 5 (on every server in case of a cluster).