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hitch.conf - Man Page

Configuration file for Hitch


hitch.conf is the configuration file for hitch(8). The configuration file is loaded using the Hitch option --config=, and can thus have different names and can exist in different locations.

Almost all options available in hitch.conf can be specified or overridden in the command line of Hitch, as described in hitch(8).

The Hitch configuration file consists of a series of option assignments.  Some options (pem-file, frontend) can be be set several times, and the effect is that multiple certificate files and "listening frontends" are defined. Other options can only be assigned once.

The hash mark, or pound sign ("#"), is used as a "comment" character. You can use it to annotate your config file. All text after the comment character to the end of the line is ignored. Empty lines are ignored.


Options can either be in the top level of the configuration file (global scope), or inside a frontend block. Options inside a frontend block only affect the frontend, while options in the top level sets defaults for all frontends.

Unless otherwise noted below, options can only be used in the top level.

alpn-protos = <protocol-list>

Comma separated list of protocols supported by the backend in a quoted string. The list is used select protocols when the client supports Next Protocol Negotiation (NPN) or Application-Layer Protocol Negotiation (ALPN). If Hitch is compiled against a OpenSSL version that does not support ALPN, only NPN will be used to select a protocol.

The result of the NPN/ALPN negotiation will be communicated to the backend if and only if write-proxy-v2 or proxy-proxy is used. For HTTP/2 to work with modern browsers, ALPN negotiation is required.

backend = ...

The endpoint Hitch connects to when receiving a connection. Only a single backend is supported.

This is either specified as "[HOST]:port" for IPv4/IPv6 endpoints:

backend = "[localhost]:8080"

Or it can be specified as a path to a UNIX domain socket:

backend = "/path/to/sock"

If the chroot setting is in effect, the UNIX domain socket path will be at runtime resolved from within the chroot, and must be specified with the path it is accessible from within the chroot. I.e. for a /run/hitch chroot and a /run/hitch/sock UNIX domain socket, configure the backend argument as /sock.

backlog = <number>

Listen backlog size

chroot = <string>

Chroot directory

ciphers = ...

List of ciphers to use in the secure communication. Refer to the OpenSSL documentation for a complete list of supported ciphers.

Each cipher in the list must be separated by a colon (:), in order of preference. See ciphers(1) for further description of the format.

If not specified, OpenSSL will allow all ciphers. System administrators are advised to either only support strong ciphers (as in the example file below) or to pay close attention to security advisories related OpenSSL's ciphers.

This option applies to TLSv1.2 and below. For TLSv1.3, see ciphersuites.

This option is also available in frontend blocks.

ciphersuites = <string>

Specifies available ciphersuites for TLSv1.3. Similar to ciphers, entries must be separated by colon (:) and sorted in order of preference.

This option is also available in frontend blocks.

client-verify = required|optional|none

Configures client certificate validation. The setting must be one of none, required or optional.

The default setting is client-verify = none, in which case Hitch will not send a certificate request to the client.

If client-verify = require is configured, Hitch will only permit connections that present a valid certificate. The certificate will be verified using the certificate provided in the client-verify-ca parameter.

If optional, Hitch will send certificate requests, but still permit connections that do not present one.

For settings optional and required, we also require that the client-verify-ca is configured.

This option is also available in frontend blocks and pem-file blocks. If specified in a frontend block, the client verification setting will only apply to the pem-file records for that particular frontend. This can also be further refined by using the option in a pem-file block, which has the effect of having it only apply to that particular pem-file record.

client-verify-ca = <string>

Specifies a file containing the certificates of the CAs that will be used to verify a client certificate.

For multiple CAs, this file can be a concatenation of multiple pem-files for the relevant certificate authorities.

This option is also available in frontend blocks and in pem-file blocks.

daemon = on|off

Run as daemon. Default is off.

frontend = ...

This specifies the port and interface (the listen endpoint) that Hitch binds to when listening for connections. It is possible define several frontends, and Hitch will bind to several ports and/or several interfaces.

If "*" is used as the host, then Hitch will bind on all interfaces for the given port.

A frontend can be specified either in a single line:

frontend = "[HOST]:PORT[+CERT]"

Or in a frontend block:

frontend = {
    host = "HOST"
    port = "PORT"
    <other frontend options>

group = <string>

If given, Hitch will change to this group after binding to listen sockets.

keepalive = <number>

Number of seconds a TCP socket is kept alive

backend-refresh = <number>

Number of seconds between periodic backend IP lookups, 0 to disable. Default is 0.

ocsp-dir = <string>

Directory where Hitch will store and read OCSP responses for stapling. Default is "/var/lib/hitch/".

Directory must be readable and writable for the configured Hitch user, or automatic retrieval and updating of OCSP responses will not take place.

If you have a manually pre-loaded OCSP staple, an alternative pem-file syntax can be used for stapling:

pem-file = {
    cert = "mycert.pem"
    ocsp-resp-file = "ocsp-resp.der"

ocsp-connect-tmo = <number>

OCSP fetch connect timeout.

This does normally not need to be changed.

Default is 4.0 seconds.

ocsp-resp-tmo = <number>

OCSP fetch response timeout.

This does normally not need to be changed.

Default is 10 seconds.

ocsp-refresh-interval = <number>

OCSP refresh interval.

If the OCSP response does not carry any refresh information, use this as the interval for refreshing.

Default is 1800 seconds.

ocsp-verify-staple = on|off

If set, OCSP responses will be verified against the certificate after retrieval.

Default is off.

pem-file = <string>

Specify a SSL x509 certificate file. Server Name Indication (SNI) is supported by using one certificate file per SNI name.

A file suitable for Hitch is a concatenation of a private key and a corresponding certificate or certificate chain.

At least one PEM file is needed for Hitch to start, but it can be supplied on the command line.

Certificates are used in the order they are listed; the last certificate listed will be used if none of the others match.

In the event that we have multiple certificates that provide the same SNI string, an error will be logged. The last loaded certificate will in that case take precedence.

For partial overlap in names, e.g. if one certificate provides "www.example.com" and another one "*.example.com", the most specific match will always take precedence at SNI lookup.

This option is also available in a frontend declaration, to make a certificate only available for a specific listen endpoint.

private-key = <string>

If set, the private key is read from specified location, not from the cert file.

pem-file = {
    cert = "mycert.pem"
    private-key = "myprivate.key"

pem-dir = <string>

Specify a directory for loading x509 certificates.

A fallback certificate for non-SNI clients may be specified by also including a separate pem-file definition.

The files are processed in lexicographic order. In the absence of any pem-file definitions, the first file entry will be used as the fallback default.

pem-dir = "/etc/hitch/cert.d"

pem-dir-glob = <string>

Matching filter for filenames loaded from pem-dir.

Default is none (match any).

pem-dir-glob = "*.pem"

prefer-server-ciphers = on|off

Turns on or off enforcement of the cipher ordering set in Hitch.

This option is also available in frontend blocks.

Default is off.

proxy-proxy = on|off

Proxy an incoming PROXY protocol header through to the backend. Supports both version 1 and 2 of the PROXY protocol.

This option is mutually exclusive with option write-proxy-v2, write-ip and write-proxy-v1.

Default is off.

log-level = <num>

Log chattiness. 0=silence, 1=errors, 2=info/debug.

This setting can also be changed at run-time by editing the configuration file followed by a reload (SIGHUP).

Default is 0.

quiet = on|off

If quiet is turned on, only error messages will be shown. This setting is deprecated in favor of log-level.

tls-protos = ...

The SSL/TLS protocols to be used. This is an unquoted list of tokens. Available tokens are SSLv3, TLSv1.0, TLSv1.1, TLSv1.2 and TLSv1.3.

The default is TLSv1.2 and TLSv1.3.

There are two deprecated options, ssl= and tls=, that also select protocols. If "ssl=on" is used, then all protocols are selected. This is known to be insecure, and is strongly discouraged. If "tls=on" is used, the three TLS protocol versions will be used. Turning on SSLv3 and TLSv1.0 is not recommended - support for these protocols are only kept for backwards compatibility.

The availability of protocol versions depend on OpenSSL version and system configuration. In particular for TLS 1.3, openssl 1.1.1 or later is required.

For supporting legacy protocol versions you may also need to lower the MinProtocol property in your OpenSSL configuration (typically /etc/ssl/openssl.cnf).

This option is also available in frontend blocks.

ecdh-curve = <string>

Sets the list of supported TLS curves. A special value of auto will leave it up to OpenSSL to automatically pick the most appropriate curve for a client.

ecdh-curve = "X25519:prime256v1:secp384r1"

sni-nomatch-abort = on|off

Abort handshake when the client submits an unrecognized SNI server name.

This option is also available in a frontend declaration.

ssl-engine = <string>

Set the SSL engine. This is used with SSL accelerator cards. See the OpenSSL documentation for legal values.

syslog = on|off

Send messages to syslog. Default is off.

syslog-facility = <string>

Set the syslog facility. Default is "daemon".

user = <string>

User to run as. If Hitch is started as root, it will insist on changing to a user with lower rights after binding to sockets.

workers = <number>|auto

Number of worker processes. One per CPU core is recommended. Using auto value creates 1 worker per CPU core.

write-ip = on|off

Report the client ip to the backend by writing IP before sending data.

This option is mutually exclusive with each of the options write-proxy-v2, write-proxy-v1 and proxy-proxy.

Default is off.

write-proxy-v1 = on|off

Report client address using the PROXY protocol.

This option is mutually exclusive with option write-proxy-v2, write-ip and proxy-proxy.

Default is off.

write-proxy-v2 = on|off

Report client address using PROXY v2 protocol.

This option is mutually exclusive with option write-ip, write-proxy-v1 and proxy-proxy.

Default is off.

proxy-tlv = on|off

Report extra information as part of the PROXYv2 header.

Currently the following will be transmitted when proxy-tlv is enabled:

  • Cipher
  • Protocol version
  • Client certificate verification result
  • Whether the client transmitted a certificate as part of this connection/session (PP2_CLIENT_CERT_CONN, PP2_CLIENT_CERT_SESS)

Default is on.

proxy-client-cert = on|off

Transmit the authenticated client certificate as part of the PROXYv2 header.

The PEM-formatted client certificate will be transmitted as a TLV field of type 0xe0.

This is a custom application-specific type, requiring a a custom handler at the recipient end. Note that using this feature will inflate the size of the PROXY header substantially, possibly also requiring tweaking at the receiving end.

tcp-fastopen = on|off

Enable TCP Fast Open.

Default is off.

backend-connect-timeout = <number>

Configures the backend connect timeout.

ssl-handshake-timeout = <number>

Configures the TLS handshake timeout.


The following file shows the syntax needed to get started with:

frontend = {
    host = "*"
    port = "443"
backend = "[]:6086"    # 6086 is the default Varnish PROXY port.
workers = 4                     # number of CPU cores

daemon = on

# We strongly recommend you create a separate non-privileged hitch
# user and group
user = "hitch"
group = "hitch"

# Enable to let clients negotiate HTTP/2 with ALPN. (default off)
# alpn-protos = "h2, http/1.1"

# run Varnish as backend over PROXY; varnishd -a :80 -a localhost:6086,PROXY ..
write-proxy-v2 = on             # Write PROXY header


This manual was written by Pål Hermunn Johansen <hermunn@varnish-software.com>

Referenced By