Module ngx_http_ssl_module
The ngx_http_ssl_module
module provides the
necessary support for HTTPS.
This module is not built by default, it should be enabled with the
--with-http_ssl_module
configuration parameter.
This module requires the OpenSSL library.
Example Configuration
To reduce the processor load it is recommended to
- set the number of worker processes equal to the number of processors,
- enable keep-alive connections,
- enable the shared session cache,
- disable the built-in session cache,
- and possibly increase the session lifetime (by default, 5 minutes):
worker_processes auto; http { ... server { listen 443 ssl; keepalive_timeout 70; ssl_protocols TLSv1 TLSv1.1 TLSv1.2; ssl_ciphers AES128-SHA:AES256-SHA:RC4-SHA:DES-CBC3-SHA:RC4-MD5; ssl_certificate /usr/local/nginx/conf/cert.pem; ssl_certificate_key /usr/local/nginx/conf/cert.key; ssl_session_cache shared:SSL:10m; ssl_session_timeout 10m; ... }
Directives
Syntax: |
ssl |
---|---|
Default: |
ssl off; |
Context: |
http , server |
Enables the HTTPS protocol for the given virtual server.
It is recommended to use the ssl
parameter of the
listen directive instead
of this directive.
Syntax: |
ssl_buffer_size |
---|---|
Default: |
ssl_buffer_size 16k; |
Context: |
http , server |
This directive appeared in version 1.5.9.
Sets the size of the buffer used for sending data.
By default, the buffer size is 16k, which corresponds to minimal overhead when sending big responses. To minimize Time To First Byte it may be beneficial to use smaller values, for example:
ssl_buffer_size 4k;
Syntax: |
ssl_certificate |
---|---|
Default: | — |
Context: |
http , server |
Specifies a file
with the certificate in the PEM format
for the given virtual server.
If intermediate certificates should be specified in addition to a primary
certificate, they should be specified in the same file in the following
order: the primary certificate comes first, then the intermediate certificates.
A secret key in the PEM format may be placed in the same file.
It should be kept in mind that due to the HTTPS protocol limitations virtual servers should listen on different IP addresses:
server { listen 192.168.1.1:443; server_name one.example.com; ssl_certificate /usr/local/nginx/conf/one.example.com.cert; ... } server { listen 192.168.1.2:443; server_name two.example.com; ssl_certificate /usr/local/nginx/conf/two.example.com.cert; ... }
otherwise the first server’s certificate will be issued for the second site.
Syntax: |
ssl_certificate_key |
---|---|
Default: | — |
Context: |
http , server |
Specifies a file
with the secret key in the PEM format
for the given virtual server.
The value
engine
:name
:id
can be specified instead of the file
(1.7.9),
which loads a secret key with a specified id
from the OpenSSL engine name
.
Syntax: |
ssl_ciphers |
---|---|
Default: |
ssl_ciphers HIGH:!aNULL:!MD5; |
Context: |
http , server |
Specifies the enabled ciphers. The ciphers are specified in the format understood by the OpenSSL library, for example:
ssl_ciphers ALL:!aNULL:!EXPORT56:RC4+RSA:+HIGH:+MEDIUM:+LOW:+SSLv2:+EXP;
The full list can be viewed using the
“openssl ciphers
” command.
The previous versions of nginx used different ciphers by default.
Syntax: |
ssl_client_certificate |
---|---|
Default: | — |
Context: |
http , server |
Specifies a file
with trusted CA certificates in the PEM format
used to verify client certificates and
OCSP responses if ssl_stapling is enabled.
The list of certificates will be sent to clients. If this is not desired, the ssl_trusted_certificate directive can be used.
Syntax: |
ssl_crl |
---|---|
Default: | — |
Context: |
http , server |
This directive appeared in version 0.8.7.
Specifies a file
with revoked certificates (CRL)
in the PEM format used to verify
client certificates.
Syntax: |
ssl_dhparam |
---|---|
Default: | — |
Context: |
http , server |
This directive appeared in version 0.7.2.
Specifies a file
with DH parameters for EDH ciphers.
Syntax: |
ssl_ecdh_curve |
---|---|
Default: |
ssl_ecdh_curve prime256v1; |
Context: |
http , server |
This directive appeared in versions 1.1.0 and 1.0.6.
Specifies a curve
for ECDHE ciphers.
Syntax: |
ssl_password_file |
---|---|
Default: | — |
Context: |
http , server |
This directive appeared in version 1.7.3.
Specifies a file
with passphrases for
secret keys
where each passphrase is specified on a separate line.
Passphrases are tried in turn when loading the key.
Example:
http { ssl_password_file /etc/keys/global.pass; ... server { server_name www1.example.com; ssl_certificate_key /etc/keys/first.key; } server { server_name www2.example.com; # named pipe can also be used instead of a file ssl_password_file /etc/keys/fifo; ssl_certificate_key /etc/keys/second.key; } }
Syntax: |
ssl_prefer_server_ciphers |
---|---|
Default: |
ssl_prefer_server_ciphers off; |
Context: |
http , server |
Specifies that server ciphers should be preferred over client ciphers when using the SSLv3 and TLS protocols.
Syntax: |
ssl_protocols
[ |
---|---|
Default: |
ssl_protocols TLSv1 TLSv1.1 TLSv1.2; |
Context: |
http , server |
Enables the specified protocols.
The TLSv1.1
and TLSv1.2
parameters work
only when the OpenSSL library of version 1.0.1 or higher is used.
TheTLSv1.1
andTLSv1.2
parameters are supported starting from versions 1.1.13 and 1.0.12, so when the OpenSSL version 1.0.1 or higher is used on older nginx versions, these protocols work, but cannot be disabled.
Syntax: |
ssl_session_cache
|
---|---|
Default: |
ssl_session_cache none; |
Context: |
http , server |
Sets the types and sizes of caches that store session parameters. A cache can be of any of the following types:
off
- the use of a session cache is strictly prohibited: nginx explicitly tells a client that sessions may not be reused.
none
- the use of a session cache is gently disallowed: nginx tells a client that sessions may be reused, but does not actually store session parameters in the cache.
builtin
- a cache built in OpenSSL; used by one worker process only. The cache size is specified in sessions. If size is not given, it is equal to 20480 sessions. Use of the built-in cache can cause memory fragmentation.
shared
- a cache shared between all worker processes. The cache size is specified in bytes; one megabyte can store about 4000 sessions. Each shared cache should have an arbitrary name. A cache with the same name can be used in several virtual servers.
Both cache types can be used simultaneously, for example:
ssl_session_cache builtin:1000 shared:SSL:10m;
but using only shared cache without the built-in cache should be more efficient.
Syntax: |
ssl_session_ticket_key |
---|---|
Default: | — |
Context: |
http , server |
This directive appeared in version 1.5.7.
Sets a file
with the secret key used to encrypt
and decrypt TLS session tickets.
The directive is necessary if the same key has to be shared between
multiple servers.
By default, a randomly generated key is used.
If several keys are specified, only the first key is used to encrypt TLS session tickets. This allows configuring key rotation, for example:
ssl_session_ticket_key current.key; ssl_session_ticket_key previous.key;
The file
must contain 48 bytes of random data and can
be created using the following command:
openssl rand 48 > ticket.key
Syntax: |
ssl_session_tickets |
---|---|
Default: |
ssl_session_tickets on; |
Context: |
http , server |
This directive appeared in version 1.5.9.
Enables or disables session resumption through TLS session tickets.
Syntax: |
ssl_session_timeout |
---|---|
Default: |
ssl_session_timeout 5m; |
Context: |
http , server |
Specifies a time during which a client may reuse the session parameters stored in a cache.
Syntax: |
ssl_stapling |
---|---|
Default: |
ssl_stapling off; |
Context: |
http , server |
This directive appeared in version 1.3.7.
Enables or disables stapling of OCSP responses by the server. Example:
ssl_stapling on; resolver 192.0.2.1;
For the OCSP stapling to work, the certificate of the server certificate issuer should be known. If the ssl_certificate file does not contain intermediate certificates, the certificate of the server certificate issuer should be present in the ssl_trusted_certificate file.
For a resolution of the OCSP responder hostname, the resolver directive should also be specified.
Syntax: |
ssl_stapling_file |
---|---|
Default: | — |
Context: |
http , server |
This directive appeared in version 1.3.7.
When set, the stapled OCSP response will be taken from the
specified file
instead of querying
the OCSP responder specified in the server certificate.
The file should be in the DER format as produced by the
“openssl ocsp
” command.
Syntax: |
ssl_stapling_responder |
---|---|
Default: | — |
Context: |
http , server |
This directive appeared in version 1.3.7.
Overrides the URL of the OCSP responder specified in the “Authority Information Access” certificate extension.
Only “http://
” OCSP responders are supported:
ssl_stapling_responder http://ocsp.example.com/;
Syntax: |
ssl_stapling_verify |
---|---|
Default: |
ssl_stapling_verify off; |
Context: |
http , server |
This directive appeared in version 1.3.7.
Enables or disables verification of OCSP responses by the server.
For verification to work, the certificate of the server certificate issuer, the root certificate, and all intermediate certificates should be configured as trusted using the ssl_trusted_certificate directive.
Syntax: |
ssl_trusted_certificate |
---|---|
Default: | — |
Context: |
http , server |
This directive appeared in version 1.3.7.
Specifies a file
with trusted CA certificates in the PEM format
used to verify client certificates and
OCSP responses if ssl_stapling is enabled.
In contrast to the certificate set by ssl_client_certificate, the list of these certificates will not be sent to clients.
Syntax: |
ssl_verify_client
|
---|---|
Default: |
ssl_verify_client off; |
Context: |
http , server |
Enables verification of client certificates.
The verification result is stored in the
$ssl_client_verify
variable.
The optional
parameter (0.8.7+) requests the client
certificate and verifies it if the certificate is present.
The optional_no_ca
parameter (1.3.8, 1.2.5)
requests the client
certificate but does not require it to be signed by a trusted CA certificate.
This is intended for the use in cases when a service that is external to nginx
performs the actual certificate verification.
The contents of the certificate is accessible through the
$ssl_client_cert
variable.
Syntax: |
ssl_verify_depth |
---|---|
Default: |
ssl_verify_depth 1; |
Context: |
http , server |
Sets the verification depth in the client certificates chain.
Error Processing
The ngx_http_ssl_module
module supports several
non-standard error codes that can be used for redirects using the
error_page directive:
- 495
- an error has occurred during the client certificate verification;
- 496
- a client has not presented the required certificate;
- 497
- a regular request has been sent to the HTTPS port.
The redirection happens after the request is fully parsed and
the variables, such as $request_uri
,
$uri
, $args
and others, are available.
Embedded Variables
The ngx_http_ssl_module
module supports
several embedded variables:
$ssl_cipher
- returns the string of ciphers used for an established SSL connection;
$ssl_client_cert
- returns the client certificate in the PEM format for an established SSL connection, with each line except the first prepended with the tab character; this is intended for the use in the proxy_set_header directive;
$ssl_client_fingerprint
- returns the SHA1 fingerprint of the client certificate for an established SSL connection (1.7.1);
$ssl_client_raw_cert
- returns the client certificate in the PEM format for an established SSL connection;
$ssl_client_serial
- returns the serial number of the client certificate for an established SSL connection;
$ssl_client_s_dn
- returns the “subject DN” string of the client certificate for an established SSL connection;
$ssl_client_i_dn
- returns the “issuer DN” string of the client certificate for an established SSL connection;
$ssl_client_verify
-
returns the result of client certificate verification:
“
SUCCESS
”, “FAILED
”, and “NONE
” if a certificate was not present; $ssl_protocol
- returns the protocol of an established SSL connection;
$ssl_server_name
- returns the server name requested through SNI (1.7.0);
$ssl_session_id
- returns the session identifier of an established SSL connection;
$ssl_session_reused
-
returns “
r
” if an SSL session was reused, or “.
” otherwise (1.5.11).