xenial (8) pound.8.gz

Provided by: pound_2.6-6.1ubuntu0.1_amd64 bug

NAME

       pound - HTTP/HTTPS reverse-proxy and load-balancer

SYNOPSIS

       pound  [-v] [-c] [-V] [-f config_file] [-p pid_file]

DESCRIPTION

       Pound  is  a  reverse-proxy  load  balancing  server.  It  accepts  requests  from HTTP/HTTPS clients and
       distributes them to one or more Web servers. The HTTPS requests are decrypted and passed to the back-ends
       as plain HTTP.

       If  more  than  one  back-end  server  is  defined,  Pound chooses one of them randomly, based on defined
       priorities. By  default,  Pound  keeps  track  of  associations  between  clients  and  back-end  servers
       (sessions).

GENERAL PRINCIPLES

       In general Pound needs three types of objects defined in order to function: listeners, services and back-
       ends.

       Listeners
              A listener is a definition of how Pound receives requests from the clients (browsers).  Two  types
              of  listeners  may be defined: regular HTTP listeners and HTTPS (HTTP over SSL/TLS) listeners.  At
              the very least a listener must  define  the  address  and  port  to  listen  on,  with  additional
              requirements for HTTPS listeners.

       Services
              A service is the definition of how the requests are answered. The services may be defined within a
              listener or at the top level (global). When a request is received Pound attempts to match them  to
              each  service  in  turn, starting with the services defined in the listener itself and, if needed,
              continuing with the services defined at the global  level.  The  services  may  define  their  own
              conditions  as  to  which  requests  they can answer: typically this involves certain URLs (images
              only, or a certain path) or specific headers (such as the Host header). A service may also  define
              a session mechanism: if defined future requests from a given client will always be answered by the
              same back-end.

       Back-ends
              The back-ends are the actual servers for the content  requested.  By  itself,  Pound  supplies  no
              responses  -  all contents must be received from a "real" web server. The back-end defines how the
              server should be contacted.

              Three types of back-ends may be defined: a "regular" back-end which receives requests and  returns
              responses,  a  "redirect"  back-end  in  which  case  Pound will respond with a redirect response,
              without accessing any back-end at all, or an "emergency" back-end which will be used only  if  all
              other backends are "dead".

              Multiple  back-ends may be defined within a service, in which case Pound will load-balance between
              the available back-ends.

              If a back-end fails to respond it will be considered "dead", in which case Pound will stop sending
              requests  to  it.  Dead back-ends are periodically checked for availability, and once they respond
              again they are "resurected" and requests are sent again their way. If no back-ends  are  available
              (none  were  defined,  or  all  are  "dead") then Pound will reply with "503 Service Unavailable",
              without checking additional services.

              The connection between Pound and the back-ends is  always  via  HTTP,  regardless  of  the  actual
              protocol used between Pound and the client.

OPTIONS

       Options available (see also below for configuration file options):

       -v     Verbose mode: error messages will be sent to stdout even if Pound was configured to log to syslog.
              This applies only to startup  messages,  before  Pound  puts  itself  in  the  background.  Normal
              operational messages will still go to syslog.

       -V     Print  version:  Pound  will exit immediately after printing the current version and configuration
              flags.

       -c     Check only: Pound will exit immediately after parsing the configuration file. This may be used for
              running a quick syntax check before actually activating a server.

       -f config_file
              Location  of  the  configuration  file (see below for a full description of the format).  Default:
              /usr/local/etc/pound.cfg

       -p pid_file
              Location of the pid file.  Pound will write its own pid into this file. Normally this is used  for
              shell scripts that control starting and stopping of the daemon.  Default: /var/run/pound.pid

       In  general,  any  number  of  back-end  servers  may  be  specified. Use the priority to affect the load
       distribution among unequal-performance servers.

       One (or more) copies of Pound should be started at boot time. Use "big iron" if you expect  heavy  loads:
       while  Pound is as light-weight as I know how to make it, with a lot of simultaneous requests it will use
       quite a bit of CPU and memory. Multiple CPUs are your friend.

CONFIGURATION FILE

       Each line in the file is  considered  a  complete  configuration  directive.  The  directives  are  case-
       insensitive.  Empty  lines  or  lines  starting  in '#' are ignored. There are three types of directives:
       global directives (they affect the settings for the entire program instance), listener  directives  (they
       define  which  requests Pound will listen for), and service directives (they affect only a specific group
       of requests).

GLOBAL DIRECTIVES

       Global directives may appear anywhere within the configuration file, though it is customary for  them  to
       be at the start. They may appear in any order.

       User "user_name"
              Specify the user Pound will run as (must be defined in /etc/passwd).

       Group "group_name"
              Specify the group Pound will run as (must be defined in /etc/group).

       RootJail "directory_path_and_name"
              Specify  the  directory  that  Pound  will chroot to at runtime. Please note that OpenSSL requires
              access to /dev/urandom, so make sure you create a device by that name, accessible  from  the  root
              jail directory.  Pound may also require access to /dev/syslog or similar.

       Daemon 0|1
              Have  Pound  run in the foreground (if 0) or as a daemon (if 1). By default Pound runs as a daemon
              (detaches itself from the controlling terminal and puts itself in the background).  By  specifying
              this  option  you  can  force Pound to work like a regular process. Useful for debugging or if you
              want to use something like daemontools.

       Threads nnn
              How many  worker  threads  Pound  should  use.  Default:  128.  Tune  this  parameter  to  improve
              performance.   If you set it too high, Pound will use a lot memory, and some CPU will be wasted on
              context switches.  If you set it too low requests may be served with  some  delay.  Experiment  to
              find the optimal value for your installation.

       LogFacility value
              Specify  the  log  facility  to use.  value (default: daemon) must be one of the symbolic facility
              names defined in syslog.h. This facility shall be used for logging. Using a  -  for  the  facility
              name causes Pound to log to stdout/stderr.

       LogLevel value
              Specify  the  logging  level:  0  for  no logging, 1 (default) for regular logging, 2 for extended
              logging (show chosen backend server as well), 3 for Apache-like format (Combined Log  Format  with
              Virtual  Host),  4  (same as 3 but without the virtual host information) and 5 (same as 4 but with
              information about the Service and BackEnd used).   This  value  can  be  overridden  for  specific
              listeners.

       IgnoreCase 0|1
              Ignore case when matching URLs (default: 0). This value can be overridden for specific services.

       DynScale 0|1
              Enable  or disable the dynamic rescaling code (default: 0). If enabled Pound will periodically try
              to modify the back-end priorities in order to equalise the response times from the  various  back-
              ends.  This value can be overridden for specific services.

       Alive value
              Specify  how  often  Pound  will  check  for  resurected  back-end hosts (default: 30 seconds). In
              general, it is a good idea to set this as low as possible - it will find resurected hosts  faster.
              However, if you set it too low it will consume resources - so beware.

       Client value
              Specify  for  how long Pound will wait for a client request (default: 10 seconds). After this long
              has passed without the client sending any data Pound will close the connection. Set it  higher  if
              your  clients  time-out  on  a  slow network or over-loaded server, lower if you start getting DOS
              attacks or run into problems  with  IE  clients.   This  value  can  be  overridden  for  specific
              listeners.

       TimeOut value
              How  long  should  Pound  wait for a response from the back-end (in seconds). Default: 15 seconds.
              This value can be overridden for specific back-ends.

       ConnTO value
              How long should Pound wait for a connection to the back-end (in  seconds).  Default:  the  TimeOut
              value. This value can be overridden for specific back-ends.

       Grace value
              How  long  should  Pound  continue to answer existing connections after a receiving and INT or HUP
              signal (default: 30 seconds). The configured listeners are closed immediately. You can bypass this
              behaviour  by  stopping  Pound with a TERM or QUIT signal, in which case the program exits without
              any delay.

       SSLEngine "name"
              Use an OpenSSL hardware acceleration  card  called  name.  Available  only  if  OpenSSL-engine  is
              installed on your system.

       Control "/path/to/socket"
              Set  the  control socket path. If not defined Pound does not listen for any commands. The commands
              may be issued by using the poundctl(8) program.

       Include "/path/to/file"
              Include the file as though it were part of the configuration file.

HTTP Listener

       An HTTP listener defines an  address  and  port  that  Pound  will  listen  on  for  HTTP  requests.  All
       configuration  directives  enclosed between ListenHTTP and End are specific to a single HTTP listener. At
       the very least you must specify and address and a port for each listener. The  following  directives  are
       available:

       Address address
              The  address  that Pound will listen on. This can be a numeric IP address, or a symbolic host name
              that must be resolvable at run-time.  This is a mandatory parameter. The address  0.0.0.0  may  be
              used  as  an  alias  for  'all available addresses on this machine', but this practice is strongly
              discouraged, as it will interfere with the rewriting mechanisms (see below).

       Port port
              The port number that Pound will listen on.  This is a mandatory parameter.

       xHTTP value
              Defines which HTTP verbs are accepted. The possible values are:

              0 (default) accept only standard HTTP requests (GET, POST, HEAD).

              1 additionally allow extended HTTP requests (PUT, PATCH, DELETE).

              2 additionally allow standard WebDAV verbs (LOCK,  UNLOCK,  PROPFIND,  PROPPATCH,  SEARCH,  MKCOL,
              MOVE, COPY, OPTIONS, TRACE, MKACTIVITY, CHECKOUT, MERGE, REPORT).

              3  additionally  allow  MS  extensions  WebDAV  verbs  (SUBSCRIBE, UNSUBSCRIBE, NOTIFY, BPROPFIND,
              BPROPPATCH, POLL, BMOVE, BCOPY, BDELETE, CONNECT).

              4 additionally allow MS RPC extensions verbs (RPC_IN_DATA, RPC_OUT_DATA).

       Client value
              Override the global Client time-out value.

       CheckURL "pattern to match"
              Define a pattern that must be matched by each request sent to this listener. A request  that  does
              not match is considered to be illegal.  By default Pound accepts all requests (i.e. the pattern is
              ".*"), but you are free to limit it to something more reasonable. Please note  that  this  applies
              only to the request path - Pound will still check that the request is syntactically correct.

       Err414 "filename"
              A file with the text to be displayed if an Error 414 occurs.  Default: "Request URI is too long.".

       Err500 "filename"
              A  file  with the text to be displayed if an Error 500 occurs.  Default: "An internal server error
              occurred. Please try again later.".

       Err501 "filename"
              A file with the text to be displayed if an Error 501 occurs.  Default: "This  method  may  not  be
              used.".

       Err503 "filename"
              A  file  with  the  text  to  be  displayed  if an Error 503 occurs.  Default: "The service is not
              available. Please try again later.".

       MaxRequest nnn
              Request maximal size. All requests will be limited to these many bytes. If a request contains more
              data than allowed an error 414 is returned. Default: unlimited.

       HeadRemove "header pattern"
              Remove certain headers from the incoming requests. All occurences of the matching specified header
              will be removed. Please note  that  this  filtering  is  done  prior  to  other  checks  (such  as
              HeadRequire  or  HeadDeny),  so  you  should  not try to check for these headers in later matches.
              Multiple directives may be specified in order to remove more  than  one  header,  and  the  header
              itself may be a regular pattern (though this should be used with caution).

       AddHeader "header: to add"
              Add the defined header to the request passed to the back-end server. The header is added verbatim.
              Use multiple AddHeader directives if you need to add more than one header.

       RewriteLocation 0|1|2
              If 1 force Pound to change the Location: and Content-location: headers in responses. If they point
              to  the  back-end  itself  or  to  the listener (but with the wrong protocol) the response will be
              changed to show the virtual host in the request. Default: 1 (active).  If the value is  set  to  2
              only  the  back-end  address  is  compared;  this  is useful for redirecting a request to an HTTPS
              listener on the same server as the HTTP listener.

       RewriteDestination 0|1
              If 1 force Pound to change the Destination: header in requests. The header is changed to point  to
              the back-end itself with the correct protocol. Default: 0.

       LogLevel value
              Override the global LogLevel value.

       Service [ "name" ]
              This  defines  a  private  service (see below for service definition syntax). This service will be
              used only by this listener. The service may be optionally named, with  the  name  showing  in  the
              poundctl listings.

HTTPS Listener

       An  HTTPS  listener  defines  an  address  and  port  that  Pound  will listen on for HTTPS requests. All
       configuration directives enclosed between ListenHTTPS and End are specific to a single HTTPS listener. At
       the  very  least  you  must  specify  and address, a port and a server certificate for each listener. All
       directives defined for HTTP listeners are applicable to HTTPS listeners as well. The following additional
       directives are also available:

       Cert "certificate file"
              Specify  the  server  certificate.  The  certificate  file is the file containing the certificate,
              possibly a certificate chain and the signature for this server. This directive  is  mandatory  for
              HTTPS listeners.

              Please  note  that  multiple  Cert directives are allowed if your OpenSSL version supports SNI. In
              such cases, the first directive is the default certificate, with additional certificates  used  if
              the client requests them.

              The ordering of the directives is important: the first certificate where the CN matches the client
              request will be used, so put your directives in the most-specific-to-least  specific  order  (i.e.
              wildcard certificates after host-specific certificates).

              Cert directives must precede all other SSL-specific directives.

       ClientCert 0|1|2|3 depth
              Ask  for  the client's HTTPS certificate: 0 - don't ask (default), 1 - ask, 2 - ask and fail if no
              certificate was presented, 3 - ask but do not verify.  Depth is the depth of  verification  for  a
              client  certificate (up to 9). The default depth limit is 9, allowing for the peer certificate and
              additional 9 CA certificates that must be verified.

       Ciphers "acceptable:cipher:list"
              This is the list of ciphers that will be accepted by the SSL connection; it is  a  string  in  the
              same format as in OpenSSL ciphers(1) and SSL_CTX_set_cipher_list(3).

       SSLHonorCipherOrder 0|1
              If this value is 1, the server will broadcast a preference to use Ciphers in the order supplied in
              the Ciphers directive.  If the value is 0, the server will treat the Ciphers list as the  list  of
              Ciphers it will accept, but no preference will be indicated.  Default value is 0.

       SSLAllowClientRenegotiation 0|1|2
              If  this  value  is  0,  client  initiated renegotiation will be disabled.  This will mitigate DoS
              exploits based on client renegotiation, regardless of the patch  status  of  clients  and  servers
              related  to "Secure renegotiation".  If the value is 1, secure renegotiation is supported.  If the
              value is 2, insecure renegotiation is supported, with unpatched clients.  /fBThis can  lead  to  a
              DoS and a Man in the Middle attack!/fR  Default value is 0.

       CAlist "CAcert_file"
              Set the list of "trusted" CA's for this server. The CAcert_file is a file containing a sequence of
              CA certificates (PEM format). The names of the defined CA certificates will be sent to the  client
              on connection.

       VerifyList "Verify_file"
              Set  the  CA  (Certificate  Authority).  The  Verify_file  is  a  file  that  contains the CA root
              certificates (in PEM format).

              Please note: there is an important difference between the CAlist and the  VerifyList.  The  CAlist
              tells  the client (browser) which client certificates it should send. The VerifyList defines which
              CAs are actually used for the verification of the returned certificate.

       CRLlist "CRL_file"
              Set the CRL (Certificate Revocation List) file. The CRL_file is a file that contains the CRLs  (in
              PEM format).

       NoHTTPS11 0|1|2
              Behave  like  an  HTTP/1.0  server for HTTPS clients. If this value is 0 disable the check. If the
              value is 1 do not allow multiple requests on SSL connections. If the value is 2 (default)  disable
              multiple  requests  on  SSL  connections  only for MSIE clients. Required work-around for a bug in
              certain versions of IE.

Service

       A service is a definition of which back-end servers Pound will use  to  reply  to  incoming  requests.  A
       service  may  be  defined as part of a listener (in which case it will be used only by that listener), or
       globally (which makes it available to all listeners).  Pound will always try the private services in  the
       order defined, followed by the global ones.

       All  configuration  directives  enclosed  between  Service  and End are specific to a single service. The
       following directives are available:

       URL "pattern"
              Match the incoming request. If a request fails to match than this service will be skipped and next
              one  tried.  If  all  services  fail  to match Pound returns an error. You may define multiple URL
              conditions per service. If no URL was defined then all requests match. The matching is by  default
              case-sensitive, but this can be overridden by specifying IgnoreCase 1

       IgnoreCase 0|1
              Override the global IgnoreCase setting.

       HeadRequire "pattern"
              The  request  must  contain  at  least on header matching the given pattern.  Multiple HeadRequire
              directives may be defined per service, in which case all of them must be satisfied.

       HeadDeny "pattern"
              The request may not contain any header matching the given pattern.  Multiple  HeadDeny  directives
              may be defined per service, in which case all of them must be satisfied.

              Please  note:  if  the  listener  defined a HeadRemove directive, the matching headers are removed
              before the service matching is attempted.

       DynScale 0|1
              Enable or disable dynamic rescaling for the current service. This value will  override  the  value
              globally defined.

       Disabled 0|1
              Start Pound with this service disabled (1) or enabled (0). If started as disabled, the service can
              be later enabled with poundctl (8).

       BackEnd
              Directives enclosed between a BackEnd and the following End directives define  a  single  back-end
              server (see below for details). You may define multiple back-ends per service, in which case Pound
              will attempt to load-balance between them.

       Redirect [code] "url"
              This is a special type of back-end. Instead of sending the request to  a  back-end  Pound  replies
              immediately with a redirection to the given URL. You may define multiple redirectors in a service,
              as well as mixing them with regular back-ends.

              The address the client is redirected to is determined by the actual url you specify: if  it  is  a
              "pure" host (i.e. with no path) then the client will be redirected to the host you specified, with
              the original request path appended. If your url does contain a  path  then  the  request  path  is
              ignored.

              Examples: if you specified

                  Redirect "http://abc.example"

              and  the client requested http://xyz/a/b/c then it will be redirected to http://abc.example/a/b/c,
              but if you specified

                  Redirect "http://abc.example/index.html"

              it will be sent to http://abc.example/index.html.

              Technical note: in an ideal world Pound should reply  with  a  "307  Temporary  Redirect"  status.
              Unfortunately,  that  is  not yet supported by all clients (in particular HTTP 1.0 ones), so Pound
              currently replies by default with a "302 Found"  instead.  You  may  override  this  behaviour  by
              specifying the code to be used (301, 302 or 307).

       Emergency
              Directives  enclosed  between  an  Emergency  and the following End directives define an emergency
              back-end server (see below for details). You may define only one  emergency  server  per  service,
              which Pound will attempt to use if all backends are down.

       Session
              Directives  enclosed  between a Session and the following End directives define a session-tracking
              mechanism for the current service. See below for details.

BackEnd

       A back-end is a definition of a single back-end server Pound will use to reply to incoming requests.  All
       configuration directives enclosed between BackEnd and End are specific to a single service. The following
       directives are available:

       Address address
              The address that Pound will connect to. This can be a numeric IP address, or a symbolic host  name
              that must be resolvable at run-time. If the name cannot be resolved to a valid address, Pound will
              assume that it represents the path for a Unix-domain socket. This is a mandatory parameter.

       Port port
              The port number that Pound will connect to. This is a  mandatory  parameter  for  non  Unix-domain
              back-ends.

       HTTPS [ "cert" ]
              The  back-end is using HTTPS. If the optional parameter cert is specified, Pound will present this
              certificate to the back-end.

       Priority val
              The priority of this back-end (between 1 and 9, 5 is default). Higher priority back-ends  will  be
              used  more often than lower priority ones, so you should define higher priorities for more capable
              servers.

       TimeOut val
              Override the global TimeOut value.

       ConnTO val
              Override the global ConnTO value.

       HAport [ address ] port
              A port (and optional address) to  be  used  for  server  function  checks.  See  below  the  "High
              Availability"  section  for  a more detailed discussion. By default Pound uses the same address as
              the back-end server, but you may use a separate address if you wish. This directive  applies  only
              to non Unix-domain servers.

       Disabled 0|1
              Start  Pound  with this back-end disabled (1) or enabled (0). If started as disabled, the back-end
              can be later enabled with poundctl (8).

Emergency

       The emergency server will be used once all existing back-ends are "dead".  All  configuration  directives
       enclosed  between  Emergency  and  End  are  specific  to  a single service. The following directives are
       available:

       Address address
              The address that Pound will connect to. This can be a numeric IP address, or a symbolic host  name
              that must be resolvable at run-time. If the name cannot be resolved to a valid address, Pound will
              assume that it represents the path for a Unix-domain socket. This is a mandatory parameter.

       Port port
              The port number that Pound will connect to. This is a  mandatory  parameter  for  non  Unix-domain
              back-ends.

Session

       Defines  how  a service deals with possible HTTP sessions.  All configuration directives enclosed between
       Session and End are specific to a single service. Once a sessions is identified, Pound  will  attempt  to
       send all requests within that session to the same back-end server.

       The following directives are available:

       Type IP|BASIC|URL|PARM|COOKIE|HEADER
              What  kind  of sessions are we looking for: IP (the client address), BASIC (basic authentication),
              URL (a request parameter), PARM (a URI parameter), COOKIE (a certain cookie), or HEADER (a certain
              request header).  This is a mandatory parameter.

       TTL seconds
              How  long  can  a  session  be idle (in seconds). A session that has been idle for longer than the
              specified number of seconds will be discarded.  This is a mandatory parameter.

       ID "name"
              The session identifier. This directive is permitted only for sessions of type URL (the name of the
              request parameter we need to track), COOKIE (the name of the cookie) and HEADER (the header name).

       See below for some examples.

HIGH-AVAILABILITY

       Pound attempts to keep track of active back-end servers, and will temporarily disable servers that do not
       respond (though not necessarily dead: an overloaded server that Pound cannot establish  a  connection  to
       will be considered dead). However, every Alive seconds, an attempt is made to connect to the dead servers
       in case they have become active again. If this attempt succeeds, connections will be  initiated  to  them
       again.

       In  general  it  is  a good idea to set this time interval as low as is consistent with your resources in
       order to benefit from resurected servers at the earliest possible time. The default value of  30  seconds
       is probably a good choice.

       The clients that happen upon a dead backend server will just receive a 503 Service Unavailable message.

       The  HAport  parameter  specifies  an  additional  port (and optionally an address) that is used only for
       viability checks: if this port is specified in a  BackEnd  directive,  Pound  will  attempt  periodically
       (every  Alive  seconds)  to  connect  to this port. If the port does not respond the server is considered
       dead.  It never makes sense to have the HAport identical to the  main  back-end  port:  this  would  only
       generate  extra,  unncecessary activity (CPU, network traffic) for no good reason whatsoever.  The HAport
       is meant for applications that offer an additional health monitoring port or for installations that  wish
       to take servers off-line in a controlled manner.

       By  default  the address of the HAport health monitor is the same as that of the back-end server. You may
       specify a different address though, for example if you have a monitoring program running on another host.

HTTPS HEADERS

       If a client browser connects to Pound via HTTPS and if it presents a client certificate  Pound  adds  the
       following headers to the request it issues to the server:

       X-SSL-Subject
              Details about the certificate owner.

       X-SSL-Issuer
              Details about the certificate issuer (Certificate Authority).

       X-SSL-notBefore
              Starting date of certificate validity.

       X-SSL-notAfter
              Ending date of certificate validity.

       X-SSL-serial
              Certificate serial number (decimal).

       X-SSL-cipher
              The cipher currently in use.

       X-SSL-certificate
              The full client certificate (PEM-format multi-line)

       It is the application's responsibility to actually use these headers - Pound just passes this information
       without checking it in any way (except for signature and encryption correctness).

SECURITY

       In general, Pound does not read or write to the hard-disk. The exceptions are reading  the  configuration
       file  and  (possibly)  the server certificate file(s) and error message(s), which are opened read-only on
       startup, read, and closed, and the pid file which is opened  on  start-up,  written  to  and  immediately
       closed.   Following  this  there  is no disk access whatsoever, so using a RootJail directive is only for
       extra security bonus points.

       Pound tries to sanitise all HTTP/HTTPS requests: the request itself, the headers  and  the  contents  are
       checked  for conformance to the RFC's and only valid requests are passed to the back-end servers. This is
       not absolutely fool-proof - as the recent Apache problem with chunked  transfers  demonstrated.  However,
       given the current standards, this is the best that can be done - HTTP is an inherently weak protocol.

ADDITIONAL NOTES

       Pound uses the system log for messages (default facility LOG_DAEMON). The format is very similar to other
       web servers, so that if you want to use a log tool:

           fgrep pound /var/log/messages | your_log_tool

       Translating HTTPS to HTTP is an iffy proposition: no client information is passed to  the  server  itself
       (certificates,  etc)  and  the backend server may be misled if it uses absolute URLs. A patch for Zope is
       included in the distribution to address this issue - for other Web servers you are on your own.  May  the
       source be with you.

       Pound  deals  with  (and sanitizes) HTTP/1.1 requests. Thus even if you have an HTTP/1.0 server, a single
       connection to an HTTP/1.1 client is kept, while the connection to the back-end  server  is  re-opened  as
       necessary.

       Pound  attempts to resolve the names of the hosts that appear in various requests and/or responses.  That
       means it need a functioning resolver of some kind (be it /etc/hosts, DNS or something else).

EXAMPLES

       To translate HTTPS requests to a local HTTP server (assuming your network address is 123.123.123.123):

              ListenHTTPS
                  Address 1.2.3.4
                  Port    443
                  Cert    "/etc/pound/server.pem"

                  Service
                      BackEnd
                          Address 127.0.0.1
                          Port    80
                      End
                  End
              End

       To distribute the HTTP/HTTPS requests to three Web servers, where the third one is  a  newer  and  faster
       machine:

              ListenHTTP
                  Address 123.123.123.123
                  Port    80
              End
              ListenHTTPS
                  Address 1.2.3.4
                  Port    443
                  Cert    "/etc/pound/server.pem"
              End

              Service
                  BackEnd
                      Address 192.168.0.10
                      Port    80
                  End
                  BackEnd
                      Address 192.168.0.11
                      Port    80
                  End
                  BackEnd
                      Address 192.168.0.12
                      Port    80
                      Priority 3
                  End
              End

       To  separate  between  image requests and other Web content and send all requests for a specific URL to a
       secure server:

              ListenHTTP
                  Address 123.123.123.123
                  Port    80
              End

              # Images server(s)
              Service
                  URL ".*.(jpg|gif)"
                  BackEnd
                      Address 192.168.0.12
                      Port    80
                  End
              End

              # redirect all requests for /forbidden
              Service
                  Url         "/forbidden.*"
                  Redirect    "https://xyzzy.com"
              End

              # Catch-all server(s)
              Service
                  BackEnd
                      Address 192.168.0.10
                      Port    80
                  End
                  BackEnd
                      Address 192.168.0.11
                      Port    80
                  End
                  Session
                      Type    BASIC
                      TTL     300
                  End
              End

       Here is a more complex example: assume your static images (GIF/JPEG) are to be served from a single back-
       end  192.168.0.10.  In  addition,  192.168.0.11  is to do the hosting for www.myserver.com with URL-based
       sessions, and 192.168.0.20 (a 1GHz PIII) and 192.168.0.21 (800Mhz  Duron)  are  for  all  other  requests
       (cookie-based  sessions).   The logging will be done by the back-end servers.  The configuration file may
       look like this:

              User        "nobody"
              Group       "nogroup"
              RootJail    "/var/pound/jail"
              Alive       60
              LogLevel    0

              # Main listening ports
              ListenHTTP
                  Address 1.2.3.4
                  Port    80
                  Client  10
              End
              ListenHTTPS
                  Address 1.2.3.4
                  Port    443
                  Cert    "/etc/pound/pound.pem"
                  Client  20
              End

              # Image server
              Service
                  URL ".*.(jpg|gif)"
                  BackEnd
                      Address 192.168.0.10
                      Port    80
                  End
              End

              # Virtual host www.myserver.com
              Service
                  URL         ".*sessid=.*"
                  HeadRequire "Host:.*www.myserver.com.*"
                  BackEnd
                      Address 192.168.0.11
                      Port    80
                  End
                  Session
                      Type    URL
                      ID      "sessid"
                      TTL     120
                  End
              End

              # Everybody else
              Service
                  BackEnd
                      Address 192.168.0.20
                      Port    80
                      Priority 5
                  End
                  BackEnd
                      Address 192.168.0.21
                      Port    80
                      Priority 4
                  End
                  Session
                      Type    COOKIE
                      ID      "userid"
                      TTL     180
                  End
              End

FILES

       /var/run/pound.nnn
              this is where Pound will attempt to record its process id.

       /usr/local/etc/pound.cfg
              the default configuration file (the location may be changed when compiling - see the  F_CONF  flag
              in the Makefile).

       /usr/local/etc/pound/cert.pem
              the  certificate  file(s) for HTTPS. The location must be defined in the configuration file - this
              is only a suggestion. The file must contain a PEM-encoded certificate,  optionally  a  certificate
              chain  from a known Certificate Authority to your server certificate and a PEM-encoded private key
              (not password protected). See OpenSSL(1) for details. This file should  be  well  protected,  lest
              someone gets your server private key.

AUTHOR

       Written by Robert Segall, Apsis GmbH.

REPORTING BUGS

       Report bugs to <roseg@apsis.ch>.

       Copyright © 2002-2010 Apsis GmbH.
       This  is  free  software;  see  the  source  for  copying conditions.  There is NO warranty; not even for
       MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.