96 lines
4.7 KiB
Markdown
96 lines
4.7 KiB
Markdown
---
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layout: "docs"
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page_title: "Encryption"
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sidebar_current: "docs-agent-encryption"
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description: |-
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The Consul agent supports encrypting all of its network traffic. The exact method of encryption is described on the encryption internals page. There are 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.html).
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There are two separate encryption systems, one for gossip traffic and one for RPC.
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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: the
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value of this setting is a configuration file containing the encryption key.
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The key must be 16-bytes, Base64 encoded. As a convenience, Consul provides the
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[`consul keygen`](/docs/commands/keygen.html) command to generate a
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cryptographically suitable key:
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```text
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$ consul keygen
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cg8StVXbQJ0gPvMd9o7yrg==
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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`](/docs/commands/agent.html) will include "Encrypted: true":
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```text
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$ cat encrypt.json
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{"encrypt": "cg8StVXbQJ0gPvMd9o7yrg=="}
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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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Atlas: <disabled>
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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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# 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](http://russellsimpkins.blogspot.com/2015/10/consul-adding-tls-using-self-signed.html)
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using OpenSSL.
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-> **Note:** Client certificates must have [Extended Key Usage](https://www.openssl.org/docs/manmaster/man5/x509v3_config.html#Extended-Key-Usage) enabled for client and server authentication.
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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.html#verify_outgoing),
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[`verify_server_hostname`](/docs/agent/options.html#verify_server_hostname),
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and [`verify_incoming`](/docs/agent/options.html#verify_incoming) options, respectively.
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If [`verify_outgoing`](/docs/agent/options.html#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 the certificate authority present on all agents, set via the agent's
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[`ca_file`](/docs/agent/options.html#ca_file) option. All server nodes must have an
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appropriate key pair set using [`cert_file`](/docs/agent/options.html#cert_file) and
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[`key_file`](/docs/agent/options.html#key_file).
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If [`verify_server_hostname`](/docs/agent/options.html#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.html#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.html#cert_file) and
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[`key_file`](/docs/agent/options.html#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.html#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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