RELAYD.CONF(5)            OpenBSD Programmer's Manual           RELAYD.CONF(5)

NAME
     relayd.conf - relay daemon configuration file

DESCRIPTION
     relayd.conf is the configuration file for the relay daemon, relayd(8).

SECTIONS
     relayd.conf is divided into six main sections:

     Macros
           User-defined variables may be defined and used later, simplifying
           the configuration file.

     Global Configuration
           Global settings for relayd(8).  Do note that the config file allows
           global settings to be added after defining tables in the config
           file, but those tables will use the built-in defaults instead of
           the global settings below them.

     Tables
           Table definitions describe a list of hosts, in a similar fashion to
           pf(4) tables.  They are used for relay, redirection, and router
           target selection with the described options and health checking on
           the host they contain.

     Redirections
           Redirections are translated to pf(4) rdr-to rules for stateful for-
           warding to a target host from a health-checked table on layer 3.

     Relays
           Relays allow application layer load balancing, SSL acceleration,
           and general purpose TCP proxying on layer 7.

     Protocols
           Protocols are predefined protocol handlers and settings for relays.

     Routers
           Routers are used to insert routes with health-checked gateways for
           (WAN) link balancing.

     Within the sections, a host address can be specified by IPv4 address,
     IPv6 address, interface name, or DNS hostname.  If the address is an in-
     terface name, relayd(8) will look up the first IPv4 address and any other
     IPv4 and IPv6 addresses of the specified network interface.  A port can
     be specified by number or name.  The port name to number mappings are
     found in the file /etc/services; see services(5) for details.

     Comments can be put anywhere in the file using a hash mark (`#'), and ex-
     tend to the end of the current line.

     Additional configuration files can be included with the include keyword,
     for example:

           include "/etc/relayd.conf.local"

MACROS
     Macros can be defined that will later be expanded in context.  Macro
     names must start with a letter, and may contain letters, digits, and un-
     derscores.  Macro names may not be reserved words (for example, table,
     relay, or timeout).  Macros are not expanded inside quotes.

     For example:

           www1="10.0.0.1"
           www2="10.0.0.2"
           table <webhosts> {
                   $www1
                   $www2
           }

GLOBAL CONFIGURATION
     Here are the settings that can be set globally:

     demote group
             Enable the global carp(4) demotion option, resetting the carp de-
             motion counter for the specified interface group to zero on
             startup and to 128 on shutdown of the daemon.  For more informa-
             tion on interface groups, see the group keyword in ifconfig(8).

     interval number
             Set the interval in seconds at which the hosts will be checked.
             The default interval is 10 seconds.

     log (updates|all)
             Log state notifications after completed host checks.  Either only
             log the updates to new states or log all state notifications,
             even if the state didn't change.  The host state can be up (the
             health check completed successfully), down (the host is down or
             didn't match the check criteria), or unknown (the host is dis-
             abled or has not been checked yet).

     prefork number
             When using relays, run the specified number of processes to han-
             dle relayed connections.  This increases the performance and pre-
             vents delays when connecting to a relay.  relayd(8) runs 5 relay
             processes by default and every process will handle all configured
             relays.

     send trap
             Send an SNMP trap when the state of a host changes.  relayd(8)
             will try to connect to snmpd(8) and request it send a trap to the
             registered trap receivers; see snmpd.conf(5) for more information
             about the configuration.

     timeout number
             Set the global timeout in milliseconds for checks.  This can be
             overridden by the timeout value in the table definitions.  The
             default interval is 200 milliseconds and it must not exceed the
             global interval.  Please note that the default value is optimized
             for checks within the same collision domain - use a higher time-
             out, such as 1000 milliseconds, for checks of hosts in other sub-
             nets.  If this option is to be set, it should be placed before
             overrides in tables.

TABLES
     Tables are used to group a set of hosts as the target for redirections or
     relays; they will be mapped to a pf(4) table for redirections.  Tables
     may be defined with the following attribute:

     disable  Start the table disabled - no hosts will be checked in this
              table.  The table can be later enabled through relayctl(8).

     Each table must contain at least one host; multiple hosts are separated
     by newline, comma, or whitespace.  Host entries may be defined with the
     following attributes:

     ip ttl number
            Change the default time-to-live value in the IP headers for host
            checks.

     parent number
            The optional parent option inherits the state from a parent host
            with the specified identifier.  The check will be skipped for this
            host and copied from the parent host.  This can be used to prevent
            multiple checks on hosts with multiple IP addresses for the same
            service.  The host identifiers are sequentially assigned to the
            configured hosts starting with 1; it can be shown with the
            relayctl(8) show summary commands.

     retry number
            The optional retry option adds a tolerance for failed host checks;
            the check will be retried for number more times before setting the
            host state to down.  If this table is used by a relay, it will al-
            so specify the number of retries for outgoing connection attempts.

     For example:

           table <service> { 192.168.1.1, 192.168.1.2, 192.168.2.3 }
           table <fallback> disable { 10.1.5.1 retry 2 }

           redirect "www" {
                   listen on www.example.com port 80
                   forward to <service> check http "/" code 200
                   forward to <fallback> check http "/" code 200
           }

     Tables are used by forward to directives in redirections or relays with a
     set of general options, health-checking rules, and timings; see the
     REDIRECTIONS and RELAYS sections for more information about the forward
     context.  Table specific configuration directives are described below.
     Multiple options can be appended to forward to directives, separated by
     whitespaces.

     The following options will configure the health-checking method for the
     table, and is mandatory for redirections:

     check http path [host hostname] code number
             For each host in the table, verify that retrieving the URL path
             gives the HTTP return code number.  If hostname is specified, it
             is used as the ``Host:'' header to query a specific hostname at
             the target host.  To validate the HTTP return code, use this
             shell command:

                   $ echo -n "HEAD <path> HTTP/1.0\r\n\r\n" | \
                           nc <host> <port> | head -n1

             This prints the status header including the actual return code:

                   HTTP/1.1 200 OK

     check https path [host hostname] code number
             This has the same effect as above but wraps the HTTP request in
             SSL.

     check http path [host hostname] digest string
             For each host in the table, verify that retrieving the URL path
             produces non-binary content whose message digest matches the de-
             fined string.  The algorithm used is determined by the string
             length of the digest argument, either SHA1 (40 characters) or MD5
             (32 characters).  If hostname is specified, it is used as the
             ``Host:'' header to query a specific hostname at the target host.
             The digest does not take the HTTP headers into account.  Do not
             specify a binary object (such as a graphic) as the target of the
             request, as relayd.conf expects the data returned to be a string.
             To compute the digest, use this simple command:

                   $ ftp -o - http://host[:port]/path | sha1

             This gives a digest that can be used as-is in a digest statement:

                   a9993e36476816aba3e25717850c26c9cd0d89d

     check https path [host hostname] digest string
             This has the same effect as above but wraps the HTTP request in
             SSL.

     check icmp
             Ping hosts in this table to determine whether they are up or not.
             This method will automatically use ICMP or ICMPV6 depending on
             the address family of each host.

     check script path
             Execute an external program to check the host state.  The program
             will be executed for each host by specifying the hostname on the
             command line:

                   /usr/local/bin/checkload.pl front-www1.private.example.com

             relayd(8) expects a positive return value on success and zero on
             failure.  Note that the script will be executed with the privi-
             leges of the "_relayd" user and terminated after timeout mil-
             liseconds.

     check send data expect pattern [ssl]
             For each host in the table, a TCP connection is established on
             the port specified, then data is sent.  Incoming data is then
             read and is expected to match against pattern using shell glob-
             bing rules.  If data is an empty string or nothing then nothing
             is sent on the connection and data is immediately read.  This can
             be useful with protocols that output a banner like SMTP, NNTP,
             and FTP.  If the ssl keyword is present, the transaction will oc-
             cur in an SSL tunnel.

     check ssl
             Perform a complete SSL handshake with each host to check their
             availability.

     check tcp
             Use a simple TCP connect to check that hosts are up.

     The following general table options are available:

     demote group
             Enable the per-table carp(4) demotion option.  This will incre-
             ment the carp demotion counter for the specified interface group
             if all hosts in the table are down.  For more information on in-
             terface groups, see the group keyword in ifconfig(8).

     interval number
             Override the global interval and specify one for this table.  It
             must be a multiple of the global interval.

     timeout number
             Set the timeout in milliseconds for each host that is checked us-
             ing TCP as the transport.  This will override the global timeout,
             which is 200 milliseconds by default.

     The following options will set the scheduling algorithm to select a host
     from the specified table:

     mode hash
             Balances the outgoing connections across the active hosts based
             on the hashed name of the table.  Additional input can be fed in-
             to the hash by looking at HTTP headers and GET variables; see the
             PROTOCOLS section below.  This mode is only supported by relays.

     mode loadbalance
             Balances the outgoing connections across the active hosts based
             on the hashed name of the table, the source and destination ad-
             dresses, and the corresponding ports.  This mode is only support-
             ed by relays.

     mode roundrobin
             Distributes the outgoing connections using a round-robin sched-
             uler through all active hosts.  This is the default mode and will
             be used if no option has been specified.  This mode is supported
             by redirections and relays.

REDIRECTIONS
     Redirections represent a pf(4) rdr-to rule.  They are used for stateful
     redirections to the hosts in the specified tables.  pf(4) rewrites the
     target IP addresses and ports of the incoming connections, operating on
     layer 3.  The configuration directives that are valid in the redirect
     context are described below:

     disable
             The redirection is initially disabled.  It can be later enabled
             through relayctl(8).

     forward to <table> [port number] options ...
             Specify the tables of target hosts to be used; see the TABLES
             section above for information about table options.  If the port
             option is not specified, the first port from the listen on direc-
             tive will be used.  This directive can be specified twice - the
             second entry will be used as the backup table if all hosts in the
             main table are down.  At least one entry for the main table is
             mandatory.

     listen on address [ip-proto] port port [interface name]
             Specify an address and a port to listen on.  pf(4) will redirect
             incoming connections for the specified target to the hosts in the
             main or backup table.  The port argument can optionally specify a
             port range instead of a single port; the format is min-port:max-
             port.  The optional argument ip-proto can be used to specify an
             IP protocol like tcp or udp; it defaults to tcp.  The rule can be
             optionally restricted to a given interface name.

     route to <table> [port number] options ...
             Like the forward to directive, but directly routes the packets to
             the target host without modifying the target address using a
             pf(4) route-to rule.  This can be used for ``direct server
             return'' to force the target host to respond via a different
             gateway.  Note that hosts have to accept sessions for the same
             address as the gateway, which is typically done by configuring a
             loopback interface on the host with this address.

     session timeout seconds
             Specify the inactivity timeout in seconds for established redi-
             rections.  The default timeout is 600 seconds (10 minutes).

     sticky-address
             This has the same effect as specifying sticky-address for an rdr-
             to rule in pf.conf(5).  It will ensure that multiple connections
             from the same source are mapped to the same redirection address.

     tag name
             Automatically tag packets passing through the pf(4) rdr-to rule
             with the name supplied.  This allows simpler filter rules.

RELAYS
     Relays will forward traffic between a client and a target server.  In
     contrast to redirections and IP forwarding in the network stack, a relay
     will accept incoming connections from remote clients as a server, open an
     outgoing connection to a target host, and forward any traffic between the
     target host and the remote client, operating on layer 7.  A relay is also
     called an application layer gateway or layer 7 proxy.

     The main purpose of a relay is to provide advanced load balancing func-
     tionality based on specified protocol characteristics, such as HTTP head-
     ers, to provide SSL acceleration and to allow basic handling of the un-
     derlying application protocol.

     The relay configuration directives are described below:

     disable
             Start the relay but immediately close any accepted connections.

     [transparent] forward [with ssl] to address [port port] options ...
             Specify the address and port of the target host to connect to.
             If the port option is not specified, the port from the listen on
             directive will be used.  Use the transparent keyword to enable
             fully-transparent mode; the source address of the client will be
             retained in this case.

             The with ssl directive enables client-side SSL mode to connect to
             the remote host.  Verification of server certificates can be en-
             abled by setting the ca file option in the protocol section.

             The following options may be specified for forward directives:

             retry number
                     The optional host retry option will be used as a toler-
                     ance for failed host connections; the connection will be
                     retried for number more times.

             inet    If the requested destination is an IPv6 address,
                     relayd(8) will forward the connection to an IPv4 address
                     which is determined by the last 4 octets of the original
                     IPv6 destination.  For example, if the original IPv6 des-
                     tination address is 2001:db8:7395:ffff::a01:101, the ses-
                     sion is relayed to the IPv4 address 10.1.1.1 (a01:101).

             inet6 address-prefix
                     If the requested destination is an IPv4 address,
                     relayd(8) will forward the connection to an IPv6 address
                     which is determined by setting the last 4 octets of the
                     specified IPv6 address-prefix to the 4 octets of the
                     original IPv4 destination.  For example, if the original
                     IPv4 destination address is 10.1.1.1 and the specified
                     address prefix is 2001:db8:7395:ffff::, the session is
                     relayed to the IPv6 address 2001:db8:7395:ffff::a01:101.

     forward to <table> [port port] options ...
             Like the previous directive, but connect to a host from the spec-
             ified table; see the TABLES section above for information about
             table options.

     forward to nat lookup options ...
             When redirecting connections with an rdr-to rule in pf.conf(5) to
             a relay listening on localhost, this directive will look up the
             real destination address of the intended target host, allowing
             the relay to be run as a transparent proxy.  If an additional
             forward to directive to a specified address or table is present,
             it will be used as a backup if the NAT lookup failed.

     listen on address [port port] [ssl]
             Specify the address and port for the relay to listen on.  The re-
             lay will accept incoming connections to the specified address.
             If the port option is not specified, the port from the listen on
             directive will be used.

             If the ssl keyword is present, the relay will accept connections
             using the encrypted SSL protocol.  The relay will look up a pri-
             vate key in /etc/ssl/private/address.key and a public certificate
             in /etc/ssl/address.crt, where address is the specified IP ad-
             dress of the relay to listen on.  See ssl(8) for details about
             SSL server certificates.

     protocol name
             Use the specified protocol definition for the relay.  The generic
             TCP protocol options will be used by default; see the PROTOCOLS
             section below.

     session timeout seconds
             Specify the inactivity timeout in seconds for accepted sessions.
             The default timeout is 600 seconds (10 minutes).

PROTOCOLS
     Protocols are templates defining actions and settings for relays.  They
     allow setting generic TCP options, SSL settings, and actions specific to
     the selected application layer protocol.

     The protocol directive is available for a number of different application
     layer protocols.  There is no generic handler for UDP-based protocols be-
     cause it is a stateless datagram-based protocol which has to look into
     the application layer protocol to find any possible state information.

     dns protocol
             (UDP) Domain Name System (DNS) protocol.  The requested IDs in
             the DNS header will be used to match the state.  relayd(8) re-
             places these IDs with random values to compensate for predictable
             values generated by some hosts.

     http protocol
             Handle the Hypertext Transfer Protocol (HTTP, or "HTTPS" if en-
             capsulated in an SSL tunnel).

     [tcp] protocol
             Generic handler for TCP-based protocols.  This is the default.

     The available configuration directives are described below:

     [direction] [type] action [marked id] [log]
             Define an action for the selected entity.  The optional log key-
             word will log the entity name and the value and the optional
             marked keyword requires that the session has been marked with a
             given identifier in order to execute the action.  The actions are
             dependent on the underlying application protocol.

     [direction] may be one of:

     request
             Handle the data stream from the client to the relay, like HTTP
             requests.  This is the default if the direction directive is
             omitted.

     response
             Handle the data stream from the target host to the relay, like
             HTTP server replies.

     [type] may be one of:

     cookie  Look up the entity as a value in the Cookie header when using the
             http protocol.  This type is only available with the direction
             request.

     header  Look up the entity in the application protocol headers, like HTTP
             headers in http mode.

     path    Look up the entity as a value in the URL path when using the http
             protocol.  This type is only available with the direction
             request.  The key will match the path of the requested URL with-
             out the hostname and query and the value will match the complete
             query, for example:

                   request path filter "/index.html"
                   request path filter "foo=bar*" from "/cgi-bin/t.cgi"

     query   Look up the entity as a query variable in the URL when using the
             http protocol.  This type is only available with the direction
             request, for example:

                   # Will match /cgi-bin/example.pl?foo=bar&ok=yes
                   request query expect "bar" from "foo"

     url     Look up the entity as a URL suffix/prefix expression consisting
             of a canonicalized hostname without port or suffix and a path
             name or prefix when using the http protocol.  This type is only
             available with the direction request, for example:

                   request url filter "example.com/index.html"
                   request url filter "example.com/test.cgi?val=1"

             relayd(8) will match the full URL and different possible suf-
             fix/prefix combinations by stripping subdomains and path compo-
             nents (up to 5 levels), and the query string.  For example, the
             following lookups will be done for
             http://www.example.com:81/1/2/3/4/5.html?query=yes:

                   www.example.com/1/2/3/4/5.html?query=yes
                   www.example.com/1/2/3/4/5.html
                   www.example.com/
                   www.example.com/1/
                   www.example.com/1/2/
                   www.example.com/1/2/3/
                   example.com/1/2/3/4/5.html?query=yes
                   example.com/1/2/3/4/5.html
                   example.com/
                   example.com/1/
                   example.com/1/2/
                   example.com/1/2/3/

     [action] may be one of:

     append value to key
             Append the specified value to a protocol entity with the selected
             name.  When using the http protocol, key will indicate a speci-
             fied HTTP header.  If key does not exist in the request, it will
             be created with the value set to value.

             The value string may contain predefined macros that will be ex-
             panded at runtime:

                   $REMOTE_ADDR  The IP address of the connected client.
                   $REMOTE_PORT  The TCP source port of the connected client.
                   $SERVER_ADDR  The configured IP address of the relay.
                   $SERVER_PORT  The configured TCP server port of the relay.
                   $SERVER_NAME  The server software name of relayd(8).
                   $TIMEOUT      The configured session timeout of the relay.

     change key to value
             Like the append directive above, but change the contents of the
             specified entity.  If key does not exist in the request, it will
             be created with the value set to value.

             The value string may contain predefined macros that will be ex-
             panded at runtime, as detailed for the append directive above.

     expect value from key
             Expect an entity key and match against value using shell globbing
             rules.  If the entity is not present or the value doesn't match,
             the connection will be dropped.

     expect [digest] key
             Expect an entity key with any possible value.  This is the short
             form of expect * from key.

             If the digest keyword is specified, compare the message digest of
             the entity against the defined string.  The algorithm used is de-
             termined by the string length of the key argument, either SHA1
             (40 characters) or MD5 (32 characters).  To compute the digest,
             use this simple command:

                   $ echo -n "example.com/path/?args" | sha1

     expect file path
             Like the directive above, but load the non-digest keys from an
             external file with the specified path containing one key per
             line.  Lines will be stripped at the first whitespace or newline
             character.  Any empty lines or lines beginning with a hash mark
             (`#') will be ignored.

     filter value from key
             Like the expect .. from directive above, but drop any connections
             with the specified entity key and a matching value.

     filter [digest] key
             Like the expect directive above, but drop any connections with
             the specified entity key and any possible value.  This is the
             short form of filter * from key.

     filter file path
             Like the directive above, but load the non-digest keys from path.
             See expect file path for more information.

     hash key
             Feed the value of the selected entity into the load balancing
             hash to select the target host.  See the table keyword in the
             RELAYS section above.

     log key
             Log the name and the value of the entity.

     log file path
             Like the directive above, but load the keys from path.  See
             expect file path for more information.

     mark [value from] key with id
             Mark the session with the specified identifier (a positive number
             between 1 and 65535) if the specified condition matches.  Note
             that the mark action does not accept the marked option (see
             above).

     label string
             Add a label to subsequently added actions.  The label will be
             printed as part of the error message if the return error option
             is set and may contain HTML tags, for example:

                   label "<a href='http://example.com/advisory.pl?id=7359'>\
                           Advisory provided by example.com</a>"
                   url filter digest 5c1e03f58f8ce0b457474ffb371fd1ef
                   url filter digest 80c1a7b8337462093ef8359c57b4d56a
                   no label

     no label
             Do not set a label for subsequently added actions; this is the
             default.

     remove key
             Remove the entity with the selected name.

     remove file path
             Like the directive above, but load the keys from path.  See
             expect file path for more information.

     return error [option]
             Return an error response to the client if an internal operation
             or the forward connection to the client failed.  By default, the
             connection will be silently dropped.  The effect of this option
             depends on the protocol: HTTP will send an error header and page
             to the client before closing the connection.  Additional valid
             options are:

             style string
                     Specify a Cascading Style Sheet (CSS) to be used for the
                     returned HTTP error pages, for example:

                           body { background: #a00000; color: white; }

     ssl option
             Set the SSL options and session settings.  This is only used if
             SSL is enabled in the relay.  Valid options are:

             ca file path
                     This option enables CA verification in SSL client mode.
                     The daemon will load the CA (Certificate Authority) cer-
                     tificates from the specified path to verify the server
                     certificates.  OpenBSD provides a default CA bundle in
                     /etc/ssl/cert.pem.

             ciphers string
                     Set the string defining the SSL cipher suite.  If not
                     specified, the default value HIGH:!ADH will be used
                     (strong crypto cipher suites without anonymous DH).  See
                     the CIPHERS section of openssl(1) for information about
                     SSL cipher suites and preference lists.

             session cache value
                     Set the maximum size of the SSL session cache.  If the
                     value is zero, the default size defined by the SSL li-
                     brary will be used.  A positive number will set the maxi-
                     mum size in bytes and the keyword disable will disable
                     the SSL session cache.

             [no] sslv2
                     Enable the SSLv2 protocol; disabled by default.

             [no] sslv3
                     Disable the SSLv3 protocol; enabled by default.

             [no] tlsv1
                     Disable the TLSv1/SSLv3.1 protocol; enabled by default.

     tcp option
             Enable or disable the specified TCP/IP options; see tcp(4) and
             ip(4) for more information about the options.  Valid options are:

             backlog number
                     Set the maximum length the queue of pending connections
                     may grow to.  The backlog option is 10 by default and is
                     limited by the kern.somaxconn sysctl(8) variable.

             ip minttl number
                     This option for the underlying IP connection may be used
                     to discard packets with a TTL lower than the specified
                     value.  This can be used to implement the Generalized TTL
                     Security Mechanism (GTSM) according to RFC 3682.

             ip ttl number
                     Change the default time-to-live value in the IP headers.

             [no] nodelay
                     Enable the TCP NODELAY option for this connection.  This
                     is recommended to avoid delays in the relayed data
                     stream, e.g. for SSH connections.

             [no] sack
                     Use selective acknowledgements for this connection.

             socket buffer number
                     Set the socket-level buffer size for input and output for
                     this connection.  This will affect the TCP window size.

ROUTERS
     Routers represent routing table entries in the kernel forwarding
     database, see route(4), and a table of associated gateways.  They are
     used to dynamically insert or remove routes with gateways based on their
     availability and health-check results.  A router can include multiple
     network statements and a single forward statement with a table of one or
     more gateways.  All entries in a single router directive must match the
     same address family, either IPv4 or IPv6.

     The kernel supports multipath routing when multiple gateways exist to the
     same destination address.  The multipath routing behaviour can be changed
     globally using the sysctl(8) variables net.inet.ip.multipath and
     net.inet6.ip6.multipath.  With the default setting of 0, the first route
     selected will be used for subsequent packets to that destination regard-
     less of source.  Setting it to 1 will enable load balancing based on the
     packet source address across gateways; multiple routes with the same pri-
     ority are used equally.  The kernel will also check the link state of the
     related network interface and try a different route if it is not active.

     The configuration directives that are valid in the routers context are
     described below:

     forward to <table> port number options ...
             Specify the table of target gateways to be used; see the TABLES
             section above for information about table options.  This entry is
             mandatory and must be specified once.

     route address/prefix
             Specify the network address and prefix length of a route destina-
             tion that is reachable via the active gateways.  This entry must
             be specified at least once in a router directive.

     rtable id
             Add the routes to the kernel routing table with the specified id.

     rtlabel label
             Add the routes with the specified label to the kernel routing
             table.

FILES
     /etc/relayd.conf                relayd(8) configuration file.

     /etc/services                   Service name database.

     /etc/ssl/address.crt
     /etc/ssl/private/address.key    Location of the relay SSL server certifi-
                                     cates, where address is the configured IP
                                     address of the relay.
     /etc/ssl/cert.pem               Default location of the CA bundle that
                                     can be used with relayd(8).

EXAMPLES
     This configuration file would create a redirection service ``www'' which
     load balances four hosts and falls back to one host containing a ``sorry
     page'':

           www1=front-www1.private.example.com
           www2=front-www2.private.example.com
           www3=front-www3.private.example.com
           www4=front-www4.private.example.com

           interval 5

           table <phphosts> { $www1, $www2, $www3, $www4 }
           table <sorryhost> disable { sorryhost.private.example.com }

           redirect "www" {
                   listen on www.example.com port 8080 interface trunk0
                   listen on www6.example.com port 80 interface trunk0

                   tag REDIRECTED

                   forward to <phphosts> port 8080 timeout 300 \
                           check http "/" digest "630aa3c2f..."
                   forward to <sorryhost> port 8080 timeout 300 check icmp
           }

     It is possible to specify multiple listen directives with different IP
     protocols in a single redirection configuration:

           redirect "dns" {
                   listen on dns.example.com tcp port 53
                   listen on dns.example.com udp port 53

                   forward to <dnshosts> port 53 check tcp
           }

     The following configuration would add a relay to forward secure HTTPS
     connections to a pool of HTTP webservers using the loadbalance mode (SSL
     acceleration and layer 7 load balancing).  The HTTP protocol definition
     will add two HTTP headers containing address information of the client
     and the server, set the ``Keep-Alive'' header value to the configured
     session timeout, and include the ``sessid'' variable in the hash to cal-
     culate the target host:

           http protocol "http_ssl" {
                   header append "$REMOTE_ADDR" to "X-Forwarded-For"
                   header append "$SERVER_ADDR:$SERVER_PORT" to "X-Forwarded-By"
                   header change "Keep-Alive" to "$TIMEOUT"
                   query hash "sessid"
                   cookie hash "sessid"
                   path filter "*command=*" from "/cgi-bin/index.cgi"

                   ssl { sslv2, ciphers "MEDIUM:HIGH" }
           }

           relay "sslaccel" {
                   listen on www.example.com port 443 ssl
                   protocol "http_ssl"
                   forward to <phphosts> port 8080 mode loadbalance check tcp
           }

     The second relay example will accept incoming connections to port 2222
     and forward them to a remote SSH server.  The TCP nodelay option will al-
     low a ``smooth'' SSH session without delays between keystrokes or dis-
     played output on the terminal:

           protocol "myssh" {
                   tcp { nodelay, socket buffer 65536 }
           }

           relay "sshforward" {
                   listen on www.example.com port 2222
                   protocol "myssh"
                   forward to shell.example.com port 22
           }

     The next simple router configuration example can be used to run redun-
     dant, health-checked WAN links:

           table <gateways> { $gw1 ip ttl 1, $gw2 ip ttl 1 }
           router "uplinks" {
                   route 0.0.0.0/0
                   forward to <gateways> check icmp
           }

SEE ALSO
     relayctl(8), relayd(8), snmpd(8), ssl(8)

HISTORY
     The relayd.conf file format, formerly known as hoststated.conf, first ap-
     peared in OpenBSD 4.1.  It was renamed to relayd.conf in OpenBSD 4.3.

AUTHORS
     The relayd(8) program was written by Pierre-Yves Ritschard
     <pyr@openbsd.org> and Reyk Floeter <reyk@openbsd.org>.

CAVEATS
     relayd(8) Verification of SSL server certificates is based on a static CA
     bundle and relayd(8) currently does not support CRLs (Certificate Revoca-
     tion Lists).

OpenBSD 4.7                    September 1, 2009                            13
