114 lines
6.0 KiB
Plaintext
114 lines
6.0 KiB
Plaintext
---
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layout: docs
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page_title: Encryption
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description: >-
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The Consul agent supports encrypting all of its network traffic. The exact
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method of encryption is described on the encryption internals page. There are
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two separate encryption systems, one for gossip traffic and one for RPC.
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---
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# Encryption
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The Consul agent supports encrypting all of its network traffic. The exact
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method of encryption is described on the [encryption internals page](/docs/internals/security).
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There are two separate encryption systems, one for gossip traffic and one for RPC.
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To configure the encryption systems on a new cluster, review this following tutorials to
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[enable gossip encryption](https://learn.hashicorp.com/tutorials/consul/gossip-encryption-secure?utm_source=consul.io&utm_medium=docs) and
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[TLS encryption for agent communication](https://learn.hashicorp.com/tutorials/consul/tls-encryption-secure?utm_source=consul.io&utm_medium=docs).
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## Gossip Encryption
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Enabling gossip encryption only requires that you set an encryption key when
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starting the Consul agent. The key can be set via the `encrypt` parameter.
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~> **WAN Joined Datacenters Note:** If using multiple WAN joined datacenters, be sure to use _the same encryption key_ in all datacenters.
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The key must be 32-bytes, Base64 encoded. As a convenience, Consul provides the
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[`consul keygen`](/commands/keygen) command to generate a
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cryptographically suitable key:
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```shell-session
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$ consul keygen
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pUqJrVyVRj5jsiYEkM/tFQYfWyJIv4s3XkvDwy7Cu5s=
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```
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With that key, you can enable encryption on the agent. If encryption is enabled,
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the output of [`consul agent`](/commands/agent) will include "Encrypt: true":
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```shell-session
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$ cat encrypt.json
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{"encrypt": "pUqJrVyVRj5jsiYEkM/tFQYfWyJIv4s3XkvDwy7Cu5s="}
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$ consul agent -data-dir=/tmp/consul -config-file=encrypt.json
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==> WARNING: LAN keyring exists but -encrypt given, using keyring
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==> WARNING: WAN keyring exists but -encrypt given, using keyring
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==> Starting Consul agent...
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==> Starting Consul agent RPC...
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==> Consul agent running!
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Node name: 'Armons-MacBook-Air.local'
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Datacenter: 'dc1'
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Server: false (bootstrap: false)
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Client Addr: 127.0.0.1 (HTTP: 8500, HTTPS: -1, DNS: 8600, RPC: 8400)
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Cluster Addr: 10.1.10.12 (LAN: 8301, WAN: 8302)
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Gossip encrypt: true, RPC-TLS: false, TLS-Incoming: false
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...
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```
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All nodes within a Consul cluster must share the same encryption key in
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order to send and receive cluster information.
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## Configuring Gossip Encryption on an existing cluster
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As of version 0.8.4, Consul supports upshifting to encrypted gossip on a running cluster
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through the following process. Review this [step-by-step tutorial](https://learn.hashicorp.com/tutorials/consul/gossip-encryption-secure#enable-gossip-encryption-existing-cluster)
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to encrypt gossip on an existing cluster.
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## RPC Encryption with TLS
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Consul supports using TLS to verify the authenticity of servers and clients. To enable this,
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Consul requires that all clients and servers have key pairs that are generated by a single
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Certificate Authority. This can be a private CA, used only internally. The
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CA then signs keys for each of the agents, as in
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[this tutorial on generating both a CA and signing keys](https://learn.hashicorp.com/tutorials/consul/tls-encryption-secure).
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~> Certificates need to be created with x509v3 extendedKeyUsage attributes for both clientAuth and serverAuth since Consul uses a single cert/key pair for both server and client communications.
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TLS can be used to verify the authenticity of the servers or verify the authenticity of clients.
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These modes are controlled by the [`verify_outgoing`](/docs/agent/options#verify_outgoing),
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[`verify_server_hostname`](/docs/agent/options#verify_server_hostname),
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and [`verify_incoming`](/docs/agent/options#verify_incoming) options, respectively.
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If [`verify_outgoing`](/docs/agent/options#verify_outgoing) is set, agents verify the
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authenticity of Consul for outgoing connections. Server nodes must present a certificate signed
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by a common certificate authority present on all agents, set via the agent's
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[`ca_file`](/docs/agent/options#ca_file) and [`ca_path`](/docs/agent/options#ca_path)
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options. All server nodes must have an appropriate key pair set using [`cert_file`](/docs/agent/options#cert_file) and [`key_file`](/docs/agent/options#key_file).
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If [`verify_server_hostname`](/docs/agent/options#verify_server_hostname) is set, then
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outgoing connections perform hostname verification. All servers must have a certificate
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valid for `server.<datacenter>.<domain>` or the client will reject the handshake. This is
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a new configuration as of 0.5.1, and it is used to prevent a compromised client from being
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able to restart in server mode and perform a MITM (Man-In-The-Middle) attack. New deployments should set this
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to true, and generate the proper certificates, but this is defaulted to false to avoid breaking
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existing deployments.
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If [`verify_incoming`](/docs/agent/options#verify_incoming) is set, the servers verify the
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authenticity of all incoming connections. All clients must have a valid key pair set using
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[`cert_file`](/docs/agent/options#cert_file) and
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[`key_file`](/docs/agent/options#key_file). Servers will
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also disallow any non-TLS connections. To force clients to use TLS,
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[`verify_outgoing`](/docs/agent/options#verify_outgoing) must also be set.
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TLS is used to secure the RPC calls between agents, but gossip between nodes is done over UDP
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and is secured using a symmetric key. See above for enabling gossip encryption.
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## Configuring TLS on an existing cluster
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As of version 0.8.4, Consul supports migrating to TLS-encrypted traffic on a running cluster
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without downtime. This process assumes a starting point with no TLS settings configured and involves
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an intermediate step in order to get to full TLS encryption. Review the
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[Securing RPC Communication with TLS Encryption tutorial](https://learn.hashicorp.com/tutorials/consul/tls-encryption-secure)
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for the step-by-step process to configure TLS on a new or existing cluster. Note the call outs there
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for existing cluster configuration.
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