stream_ssl module#

Provides the necessary support for a stream proxy server to work with the SSL/TLS protocol.

This module isn’t built by default; it should be enabled with the ‑‑with‑stream_ssl_module configuration parameter.

Packages in our repositories have this module built.

Important

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 the shared session cache,

  • disable the built-in session cache,

  • and possibly increase the session lifetime (by default, 5 minutes):

worker_processes auto;

stream {

    #...

    server {
        listen              12345 ssl;

        ssl_protocols       TLSv1 TLSv1.1 TLSv1.2 TLSv1.3;
        ssl_ciphers         AES128-SHA:AES256-SHA:RC4-SHA:DES-CBC3-SHA:RC4-MD5;
        ssl_certificate     /usr/local/angie/conf/cert.pem;
        ssl_certificate_key /usr/local/angie/conf/cert.key;
        ssl_session_cache   shared:SSL:10m;
        ssl_session_timeout 10m;

    #    ...
    }

Directives#

ssl_alpn#

Syntax:

ssl_alpn protocol …;

Default:

Context:

stream, server

Specifies the list of supported ALPN protocols. One of the protocols must be negotiated if the client uses ALPN:

map $ssl_alpn_protocol $proxy {
    h2                 127.0.0.1:8001;
    http/1.1           127.0.0.1:8002;
}

server {
    listen      12346;
    proxy_pass  $proxy;
    ssl_alpn    h2 http/1.1;
}

ssl_certificate#

Syntax:

ssl_certificate file [file];

Default:

Context:

stream, server

Specifies a file with the certificate in the PEM format for the given 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.

This directive can be specified multiple times to load certificates of different types, for example, RSA and ECDSA:

server {
    listen              12345 ssl;

    ssl_certificate     example.com.rsa.crt;
    ssl_certificate_key example.com.rsa.key;

    ssl_certificate     example.com.ecdsa.crt;
    ssl_certificate_key example.com.ecdsa.key;

#    ...
}

Only OpenSSL 1.0.2 or higher supports separate certificate chains for different certificates. With older versions, only one certificate chain can be used.

Important

Variables can be used in the file name when using OpenSSL 1.0.2 or higher:

ssl_certificate     $ssl_server_name.crt;
ssl_certificate_key $ssl_server_name.key;

Note that using variables implies that a certificate will be loaded for each SSL handshake, and this may have a negative impact on performance.

The value “data:$variable” can be specified instead of the file, which loads a certificate from a variable without using intermediate files.

Note that inappropriate use of this syntax may have its security implications, such as writing secret key data to error log.

New in version 1.2.0.

When ssl_ntls enabled, directive accepts two arguments instead of one: sign and encryption parts of certificate:

listen ... ssl;

ssl_ntls  on;

# dual NTLS certificate
ssl_certificate      sign.crt enc.crt;
ssl_certificate_key  sign.key enc.key;

# can be combined with regular RSA certificate:
ssl_certificate  rsa.crt;
ssl_certificate  rsa.key;

ssl_certificate_key#

Syntax:

ssl_certificate_key file [file];

Default:

Context:

stream, server

Specifies a file with the secret key in the PEM format for the given server.

Important

Variables can be used in the file name when using OpenSSL 1.0.2 or higher.

The value “engine:name:id” can be specified instead of the file, which loads a secret key with a specified id from the OpenSSL engine name.

The value “data:$variable” can be specified instead of the file, which loads a secret key from a variable without using intermediate files. Note that inappropriate use of this syntax may have its security implications, such as writing secret key data to error log.

New in version 1.2.0.

When ssl_ntls enabled, directive accepts two arguments instead of one: sign and encryption parts of key:

listen ... ssl;

ssl_ntls  on;

# dual NTLS certificate
ssl_certificate      sign.crt enc.crt;
ssl_certificate_key  sign.key enc.key;

# can be combined with regular RSA certificate:
ssl_certificate  rsa.crt;
ssl_certificate  rsa.key;

ssl_ciphers#

Syntax:

ssl_ciphers ciphers;

Default:

ssl_ciphers HIGH:!aNULL:!MD5;

Context:

stream, 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.

ssl_client_certificate#

Syntax:

ssl_client_certificate file;

Default:

Context:

stream, server

Specifies a file with trusted CA certificates in the PEM format used to verify client certificates.

The list of certificates will be sent to clients. If this is not desired, the ssl_trusted_certificate directive can be used.

ssl_conf_command#

Syntax:

ssl_conf_command name value;

Default:

Context:

stream, server

Sets arbitrary OpenSSL configuration commands.

Important

The directive is supported when using OpenSSL 1.0.2 or higher.

Several ssl_conf_command directives can be specified on the same level:

ssl_conf_command Options PrioritizeChaCha;
ssl_conf_command Ciphersuites TLS_CHACHA20_POLY1305_SHA256;

These directives are inherited from the previous configuration level if and only if there are no ssl_conf_command directives defined on the current level.

Caution

Note that configuring OpenSSL directly might result in unexpected behavior.

ssl_crl#

Syntax:

ssl_crl file;

Default:

Context:

stream, server

Specifies a file with revoked certificates (CRL) in the PEM format used to verify client certificates.

ssl_dhparam#

Syntax:

ssl_dhparam file;

Default:

Context:

stream, server

Specifies a file with DH parameters for DHE ciphers.

Caution

By default no parameters are set, and therefore DHE ciphers will not be used.

ssl_ecdh_curve#

Syntax:

ssl_ecdh_curve curve;

Default:

ssl_ecdh_curve auto;

Context:

stream, server

Specifies a curve for ECDHE ciphers.

Important

When using OpenSSL 1.0.2 or higher, it is possible to specify multiple curves, for example:

ssl_ecdh_curve prime256v1:secp384r1;

The special value auto instructs Angie to use a list built into the OpenSSL library when using OpenSSL 1.0.2 or higher, or prime256v1 with older versions.

Important

When using OpenSSL 1.0.2 or higher, this directive sets the list of curves supported by the server. Thus, in order for ECDSA certificates to work, it is important to include the curves used in the certificates.

ssl_handshake_timeout#

Syntax:

ssl_handshake_timeout time;

Default:

ssl_handshake_timeout 60s;

Context:

stream, server

Specifies a timeout for the SSL handshake to complete.

ssl_ntls#

New in version 1.2.0.

Syntax:

ssl_ntls on | off;

Default:

ssl_ntls off;

Context:

stream, server

Enables server-side support for NTLS using TongSuo library.

listen ... ssl;
ssl_ntls  on;

Important

Build Angie using the –with-ntls configure option and link with NTLS-enabled SSL library

./configure --with-openssl=../Tongsuo-8.3.0 \
            --with-openssl-opt=enable-ntls  \
            --with-ntls

ssl_password_file#

Syntax:

ssl_password_file file;

Default:

Context:

stream, server

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:

stream {
    ssl_password_file /etc/keys/global.pass;
    ...

    server {
        listen 127.0.0.1:12345;
        ssl_certificate_key /etc/keys/first.key;
    }

    server {
        listen 127.0.0.1:12346;

        # named pipe can also be used instead of a file
        ssl_password_file /etc/keys/fifo;
        ssl_certificate_key /etc/keys/second.key;
    }
}

ssl_prefer_server_ciphers#

Syntax:

ssl_prefer_server_ciphers on | off;

Default:

ssl_prefer_server_ciphers off;

Context:

stream, server

Specifies that server ciphers should be preferred over client ciphers when the SSLv3 and TLS protocols are used.

ssl_protocols#

Syntax:

ssl_protocols [SSLv2] [SSLv3] [TLSv1] [TLSv1.1] [TLSv1.2] [TLSv1.3];

Default:

ssl_protocols TLSv1 TLSv1.1 TLSv1.2 TLSv1.3;

Context:

stream, server

Changed in version 1.2.0: TLSv1.3 parameter added to default set.

Enables the specified protocols.

Important

The TLSv1.1 and TLSv1.2 parameters work only when OpenSSL 1.0.1 or higher is used.

The TLSv1.3 parameter works only when OpenSSL 1.1.1 or higher is used.

ssl_session_cache#

Syntax:

ssl_session_cache off | none | [builtin[:size]] [shared:name:size];

Default:

ssl_session_cache none;

Context:

stream, 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: Angie explicitly tells a client that sessions may not be reused.

none

the use of a session cache is gently disallowed: Angie 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 servers. It is also used to automatically generate, store, and periodically rotate TLS session ticket keys unless configured explicitly using the ssl_session_ticket_key directive.

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.

ssl_session_ticket_key#

Syntax:

ssl_session_ticket_key file;

Default:

Context:

stream, server

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 80 or 48 bytes of random data and can be created using the following command:

openssl rand 80 > ticket.key

Depending on the file size either AES256 (for 80-byte keys) or AES128 (for 48-byte keys) is used for encryption.

ssl_session_tickets#

Syntax:

ssl_session_tickets on | off;

Default:

ssl_session_tickets on;

Context:

stream, server

Enables or disables session resumption through TLS session tickets.

ssl_session_timeout#

Syntax:

ssl_session_timeout time;

Default:

ssl_session_timeout 5m;

Context:

stream, server

Specifies a time during which a client may reuse the session parameters.

ssl_trusted_certificate#

Syntax:

ssl_trusted_certificate file;

Default:

Context:

stream, server

Specifies a file with trusted CA certificates in the PEM format used to verify client certificates.

In contrast to the certificate set by ssl_client_certificate, the list of these certificates will not be sent to clients.

ssl_verify_client#

Syntax:

ssl_verify_client on | off | optional | optional_no_ca;

Default:

ssl_verify_client off;

Context:

stream, server

Enables verification of client certificates. The verification result is stored in the $ssl_client_verify variable. If an error has occurred during the client certificate verification or a client has not presented the required certificate, the connection is closed.

optional

requests the client certificate and verifies it if the certificate is present.

optional_no_ca

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 Angie performs the actual certificate verification.

ssl_verify_depth#

Syntax:

ssl_verify_depth number;

Default:

ssl_verify_depth 1;

Context:

stream, server

Sets the verification depth in the client certificates chain.

Built-in Variables#

The stream_ssl module supports the following variables:

$ssl_alpn_protocol#

returns the protocol selected by ALPN during the SSL handshake, or an empty string otherwise.

$ssl_cipher#

returns the name of the cipher used for an established SSL connection.

$ssl_ciphers#

returns the list of ciphers supported by the client. Known ciphers are listed by names, unknown are shown in hexadecimal, for example:

AES128-SHA:AES256-SHA:0x00ff

Important

The variable is fully supported only when using OpenSSL version 1.0.2 or higher. With older versions, the variable is available only for new sessions and lists only known ciphers.

$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.

$ssl_client_fingerprint#

returns the SHA1 fingerprint 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 according to RFC 2253.

$ssl_client_raw_cert#

returns the client certificate in the PEM format for an established SSL connection.

$ssl_client_s_dn#

returns the “subject DN” string of the client certificate for an established SSL connection according to RFC 2253.

$ssl_client_serial#

returns the serial number of the client certificate for an established SSL connection.

$ssl_client_v_end#

returns the end date of the client certificate.

$ssl_client_v_remain#

returns the number of days until the client certificate expires.

$ssl_client_v_start#

returns the start date of the client certificate.

$ssl_client_verify#

returns the result of client certificate verification: SUCCESS, “FAILED:reason” and NONE if a certificate was not present.

$ssl_curve#

returns the negotiated curve used for SSL handshake key exchange process. Known curves are listed by names, unknown are shown in hexadecimal, for example:

prime256v1

Important

The variable is supported only when using OpenSSL version 3.0 or higher. With older versions, the variable value will be an empty string.

$ssl_curves#

returns the list of curves supported by the client. Known curves are listed by names, unknown are shown in hexadecimal, for example:

0x001d:prime256v1:secp521r1:secp384r1

Important

The variable is supported only when using OpenSSL version 1.0.2 or higher. With older versions, the variable value will be an empty string.

The variable is available only for new sessions.

$ssl_protocol#

returns the protocol of an established SSL connection.

$ssl_server_name#

returns the server name requested through SNI.

$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