-*- Fundamental -*-

Sections

  [<servername> - <clientaddr>]
  [<clientaddr>]
  [<servername>]   usually [SERVER]
  [DEFAULT]

Keys are looked up in that order.  <servername> must not
be a valid IPv4 or IPv6 address.

Exceptional settings:

  server

     Specifies <servername>.
     Is looked up in [SERVER] and [DEFAULT] only.
     If not specified there, it is SERVER.

  password

     Looked up in the usual way, but used by client to
     determine its own <clientaddr>s.

     The client will create a local interface, and try to communicate
     with the server, for Each (<servername>,<clientaddr>) pair for
     which the config search yields a password.

     On the server: clients with no password are ignored.

Capped settings:

     Values in <servername> are a cap (maximum) on those from the
     other sections (including DEFAULT):

  max_batch_down
     Size limit for response payloads (server only) [65536 bytes]

  max_queue_time
     Discard downwards packets after this long (server only) [10 s]

  http_timeout
     (On server) return with empty payload any http request oustanding
      for this long
     (On client) give up on any http request outstanding for
      for this long plus http_timeout_grace
     Client's effective timeout must be at least server's (checked).
     [30 s]

  target_requests_outstanding   
     (On server) whenever number of outstanding requests for
      a client exceeds this, return oldest with empty payload
     (On client) try to keep this many requests outstanding.
     Must match between client and server (checked).  [3]

Ordinary settings, used by client and server:

  ipif
     Command to run to create and communicate with local network
     interface.  Passed to sh -c.  Must speak SLIP on stdin/stdout.
     The following additional interpolations aare substituted:
                       %(local)s      %(peer)s       %(rnet)s
          on server    <vaddr>        <vrelay>       <vnetwork>
          on client    <client>       <vaddr>        <vroutes>
     ["userv root ipif %(local)s,%(peer)s,%(mtu)s,slip %(rnets)s"]

  addrs
     Public IP (v4 or v6) address(es) of the server;
     space-separated.
     (On server) mandatory; used for bind.  No default.
     (On client) used only to construct default url.

  vnetwork
     Private network range (<prefix>/<length>).  Must contain all
     <client>s.  Must contain <vaddr> and <vrelay>, and used
     to compute their defaults.  [172.24.230.192/28]

  vaddr
     Address of server's virtual interface.

  vrelay
     Virtual point-to-point address used for tunnel routing
     (does not appear in packets).
     [first host entry in <vnetwork> other than <vaddr>,
      so 172.24.230.194]

  port
     Public port number of the server.  [80]
     (On server) used for bind.
     (On client) used only to construct default url.

  mtu
     Must match exactly.  (checked) [1500 bytes]

Ordinary settings, used by client only:

  http_timeout_grace
     See http_timeout.  [5 s]

  max_requests_outstanding
     Client will hold off sending more requests than this to
     server even if it has data to send.  [6]

  max_batch_up
     Size limit for request payloads. [4000 bytes]

  http_retry
     If a request fails, wait this long before considering it
     "finished" - to limit rate of futile requests.  [5 s]

  url
     Public url of server.
     [http://<first-entry-in-addrs>:<port>/]

  vroutes
     Virtual addresses (in CIDR syntax) to be found at the server
     end, space-separated.  Routes to those will be created on
     the client.  [""]