Document updated on Feb 28, 2023
Enabling TLS for HTTPS and HTTP/2
There are two different strategies when using TLS over KrakenD:
- Use TLS for HTTPS and HTTP/2 in KrakenD (this document)
- Use a balancer with TLS termination in front of KrakenD (e.g., ELB, HAproxy)
If you want to enable TLS, add a tls
key at the service level (configuration’s file root) with at least the public and private keys. When you add TLS, KrakenD listens only using TLS, and no traffic to plain HTTP is accepted.
If you want to enable mTLS see Mutual TLS configuration
TLS Configuration
To start KrakenD with TLS, you need to provide a certificate for both the public and the private keys:
{
"version": 3,
"tls": {
"public_key": "/path/to/cert.pem",
"private_key": "/path/to/key.pem"
}
}
All TLS options are described below:
Fields of TLS/SSL
Minimum configuration needs any of:
public_key
+
private_key
, or
null
object
ca_certs
array- An array with all the CA certificates you would like to load to KrakenD when using mTLS, in addition to the certificates present in the system’s CA.Example:
["ca.pem"]
Defaults to[]
cipher_suites
array- The list of cipher suites as defined in the documentation.Defaults to
[4865,4866,4867]
curve_preferences
array- The list of all the identifiers for the curve preferences. Use
23
for CurveP256,24
for CurveP384 or25
for CurveP521.Defaults to[23,24,25]
disable_system_ca_pool
boolean- Ignore any certificate in the system’s CA. The only certificates loaded will be the ones in the
ca_certs
list when true.Defaults tofalse
disabled
boolean- A flag to disable TLS (useful while in development).Defaults to
false
enable_mtls
boolean- Whether to enable or not Mutual Authentication. When mTLS is enabled, all KrakenD endpoints require clients to provide a known client-side X.509 authentication certificate. KrakenD relies on the system’s CA to validate certificates.Defaults to
false
max_version
- Maximum TLS version supported.Possible values are:
"SSL3.0"
,"TLS10"
,"TLS11"
,"TLS12"
,"TLS13"
Defaults to"TLS13"
min_version
- Minimum TLS version supported. When specifiying very old and insecure versions under TLS12 you must provide the
ciphers_list
.Possible values are:"SSL3.0"
,"TLS10"
,"TLS11"
,"TLS12"
,"TLS13"
Defaults to"TLS13"
prefer_server_cipher_suites
boolean- Enforces the use of TLS versions and cipher suites configured, and blocks all traffic not in the range.Defaults to
false
private_key
string- Absolute path to the private key, or relative to the current working directory.Examples:
"/path/to/key.pem"
,"./certs/key.pem"
Defaults to"./certs/key.pem"
public_key
string- Absolute path to the public key, or relative to the current working directory.Examples:
"/path/to/cert.pem"
,"./certs/cert.pem"
Defaults to"./certs/cert.pem"
Supporting older TLS 1.2 and below
Although we do not recommend downgrading your installation, this is the configuration you will need to support older protocol versions.
Support old TLS v1.2
To support TLS v1.2 and 1.3 simultaneously, you need the following configuration. As you are accepting older cipher suites, it is recommended to add the flag prefer_server_cipher_suites
to block clients from trying to negotiate weaker cipher suites:
{
"version": 3,
"tls": {
"public_key": "/path/to/cert.pem",
"private_key": "/path/to/key.pem",
"min_version": "TLS12",
"prefer_server_cipher_suites": true
}
}
Support archaic TLS versions
To support versions older than 1.2, specify the list of cipher_suites
you want to enable and the prefer_server_cipher_suites
set to true
.
Supported cipher suites
You can select which cipher_suites
you’d like to support by passing an array of integers. The possible values of the cipher suites are listed below. The recommendation is to stay with TLS 1.3, or downgrade to TLS 1.2 when strongly needed. Down that should be out of the table.
Default suites for TLS 1.3 are:
4865
: TLS_AES_128_GCM_SHA2564866
: TLS_AES_256_GCM_SHA3844867
: TLS_CHACHA20_POLY1305_SHA256
Default suites for TLS 1.2 are:
49199
: TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA25649200
: TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA38452392
: TLS_ECDHE_RSA_WITH_CHACHA20_POLY130549196
: TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA38452393
: TLS_ECDHE_ECDSA_WITH_CHACHA20_POLY130549195
: TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256
Other cipher_suites
are supported but not recommended. Their existence is to support legacy systems:
5
: TLS_RSA_WITH_RC4_128_SHA10
: TLS_RSA_WITH_3DES_EDE_CBC_SHA47
: TLS_RSA_WITH_AES_128_CBC_SHA53
: TLS_RSA_WITH_AES_256_CBC_SHA60
: TLS_RSA_WITH_AES_128_CBC_SHA256156
: TLS_RSA_WITH_AES_128_GCM_SHA256157
: TLS_RSA_WITH_AES_256_GCM_SHA38449159
: TLS_ECDHE_ECDSA_WITH_RC4_128_SHA49161
: TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA49162
: TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA49169
: TLS_ECDHE_RSA_WITH_RC4_128_SHA49170
: TLS_ECDHE_RSA_WITH_3DES_EDE_CBC_SHA49171
: TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA49172
: TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA49187
: TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA25649191
: TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256
Generating certificates
You can acquire, use external tools, or self-generate your certificates.
For example, to generate a self-signed certificate from the command line, you can do the following:
Generate a certificate
$openssl req -newkey rsa:2048 -new -nodes -x509 -days 365 -out cert.pem -keyout key.pem \
-subj "/C=US/ST=California/L=Mountain View/O=Your Organization/OU=Your Unit/CN=localhost"
Common TLS errors
Self-signed certificates will show in the logs:
http: TLS handshake error from 172.17.0.1:45474: local error: tls: bad record MAC
Old clients trying to connect to a newer TLS version, will produce errors as follows:
http: TLS handshake error from 172.17.0.1:33698: tls: unsupported SSLv2 handshake received
http: TLS handshake error from 172.17.0.1:33710: tls: client offered only unsupported versions
Incompatible curves offered by client:
http: TLS handshake error from 172.17.0.1:33810: tls: no cipher suite supported by both client and server
http: TLS handshake error from 172.17.0.1:33814: tls: no ECDHE curve supported by both client and server
When the client offers a limited set of options that the server cannot accept. It will hang up the connection with an End Of File:
http: TLS handshake error from 172.17.0.1:33990: EOF
SSL scan results for the default settings
The following output is the results of the sslscan command with a KrakenD configuration specifying the private and public keys in the configuration with no other additional tls
settings:
Version: 2.0.15-7-gbc46606-static
OpenSSL 1.1.1u-dev xx XXX xxxx
Connected to ::1
Testing SSL server localhost on port 443 using SNI name localhost
SSL/TLS Protocols:
SSLv2 disabled
SSLv3 disabled
TLSv1.0 disabled
TLSv1.1 disabled
TLSv1.2 disabled
TLSv1.3 enabled
TLS Fallback SCSV:
Server supports TLS Fallback SCSV
TLS renegotiation:
Session renegotiation not supported
TLS Compression:
Compression disabled
Heartbleed:
TLSv1.3 not vulnerable to heartbleed
Supported Server Cipher(s):
Preferred TLSv1.3 128 bits TLS_AES_128_GCM_SHA256 Curve P-521 DHE 521
Accepted TLSv1.3 256 bits TLS_AES_256_GCM_SHA384 Curve P-521 DHE 521
Accepted TLSv1.3 256 bits TLS_CHACHA20_POLY1305_SHA256 Curve P-521 DHE 521
Server Key Exchange Group(s):
TLSv1.3 128 bits secp256r1 (NIST P-256)
TLSv1.3 192 bits secp384r1 (NIST P-384)
TLSv1.3 260 bits secp521r1 (NIST P-521)
SSL Certificate:
Signature Algorithm: sha256WithRSAEncryption
RSA Key Strength: 2048
Subject: localhost
Issuer: localhost
Not valid before: Feb 28 11:44:05 2023 GMT
Not valid after: Feb 28 11:44:05 2024 GMT