Provided by: rfc5766-turn-server_3.2.3.1-1_amd64 bug

GENERAL INFORMATION

       The  TURN  Server  project  contains  the  source  code  of  a TURN server and TURN client
       messaging library. Also, some extra programs provided, for testing-only purposes.

       See the INSTALL file for the building instructions.

       After the build, you will have the following binary images:

       1.     turnserver: TURN Server relay.  The  compiled  binary  image  of  the  TURN  Server
              program is located in bin/ sub-directory.

       2.     turnadmin: TURN administration tool. See README.turnadmin and turnadmin man page.

       3.     turnutils_uclient. See README.turnutils and turnutils man page.

       4.     turnutils_peer. See README.turnutils and turnutils man page.

       5.     turnutils_stunclient. See README.turnutils and turnutils man page.

       6.     turnutils_rfc5769check. See README.turnutils and turnutils man page.

       In the "examples/scripts" sub-directory, you will find the examples of command lines to be
       used to run the programs. The scripts are meant to be run  from  examples/  sub-directory,
       for example:

       $ cd examples $ ./scripts/secure_relay.sh

RUNNING THE TURN SERVER

       Options  note: turnserver has long and short option names, for most options.  Some options
       have only long form, some options have only short form. Their syntax  somewhat  different,
       if an argument is required:

       The short form must be used as this (for example):

         $ turnserver -L 12.34.56.78

       The long form equivalent must use the "=" character:

         $ turnserver --listening-ip=12.34.56.78

       If  this  is  a  flag  option  (no  argument  required) then their usage are the same, for
       example:

        $ turnserver -a

       is equivalent to:

        $ turnserver --lt-cred-mech

       =====================================

   NAME
        turnserver - a TURN relay server implementation.

   SYNOPSIS
       $ turnserver [-n | -c <config-file> ] [flags] [ --userdb=<userdb-file> | --psql-userdb=<db-conn-string> | --mysql-userdb=<db-conn-string>  | --redis-userdb=<db-conn-string> ] [-z | --no-auth | -a | --lt-cred-mech ] [options]
       $ turnserver -h

   DESCRIPTION
       Config file settings:

       -n     Do not use configuration file, use only command line parameters.

       -c     Configuration file name (default - turnserver.conf).  The format of config file can
              be  seen  in  the supplied examples/etc/turnserver.conf example file. Long names of
              the options are used as the configuration items  names  in  the  file.  If  not  an
              absolute path is supplied, then the file is searched in the following directories:

              ·  current directory

              ·  current directory etc/ sub-directory

              ·  upper directory level etc/

              ·  /etc/

              ·  /usr/local/etc/

              ·  installation directory /etc

       User database settings:

       -b, --userdb
              User  database  file  name  (default  - turnuserdb.conf), for long-term credentials
              mechanism only.  This user file database is being  dynamically  checked  while  the
              turnserver  is working, and the user accounts can be changed dynamically by editing
              the database.

       -e, --psql-userdb
              User database connection string for PostgreSQL.  This  database  can  be  used  for
              long-term  and short-term credentials mechanisms, and it can store the secret value
              for secret-based timed authentication in TURN  RESP  API.   The  connection  string
              format is like that:

              "host=<host>     dbname=<dbname>     user=<db-user>     password=<db-user-password>
              connect_timeout=<seconds>" (for 8.x or newer Postgres).

              Or:

              "postgresql://username:password@hostname:port/databasename"  (for  9.x   or   newer
              Postgres).  See the INSTALL file for more explanations and examples.

              Also, see http://www.PostgreSQL.org for full PostgreSQL documentation.

       -M, --mysql-userdb
              User  database  connection  string for MySQL or MariaDB.  This database can be used
              for long-term and short-term credentials mechanisms, and it can  store  the  secret
              value  for  secret-based  timed  authentication  in  TURN RESP API.  The connection
              string format is like that:

              "host=<host>     dbname=<dbname>     user=<db-user>     password=<db-user-password>
              connect_timeout=<seconds>" See the INSTALL file for more explanations and examples.

              Also, see http://www.mysql.org or http://mariadb.org for full MySQL documentation.

       -N, --redis-userdb
              User database connection string for Redis.  This database can be used for long-term
              and short-term credentials mechanisms, and  it  can  store  the  secret  value  for
              secret-based  timed  authentication in TURN RESP API.  The connection string format
              is like that:

              "ip=<ip-addr> dbname=<db-number> password=<db-password>  connect_timeout=<seconds>"
              See the INSTALL file for more explanations and examples.

              Also, see http://redis.io for full Redis documentation.

       Flags:

       -v, --verbose
              Moderate verbose mode.

       -V, --Verbose
              Extra verbose mode, very annoying and not recommended.

       -o, --daemon
              Run server as daemon.

       -f, --fingerprint
              Use  fingerprints  in  the  TURN  messages.  If  an  incoming  request  contains  a
              fingerprint, then TURN server will always add fingerprints to the messages in  this
              session, regardless of the per-server setting.

       -a, --lt-cred-mech
              Use  long-term  credentials  mechanism  (this one you need for WebRTC usage).  This
              option can be used with either flat file user database or PostgreSQL DB or MySQL DB
              or Redis for user keys storage.

       -A, --st-cred-mech
              Use  the  short-term  credentials  mechanism.  This option requires a PostgreSQL or
              MySQL or Redis DB for short term passwords storage.

       -z, --no-auth
              Do not use any credentials mechanism, allow anonymous access.  Opposite to  -a  and
              -A  options. This is default option when no authentication-related options are set.
              By default, no credential mechanism is used - any user is allowed.

       --use-auth-secret
              TURN REST API flag.  Flag that sets a special WebRTC authorization option  that  is
              based  upon  authentication  secret. The feature purpose is to support "TURN Server
              REST API" as described in the TURN  REST  API  section  below.   This  option  uses
              timestamp as part of combined username: usercombo -> "user_id:timestamp", turn user
              -> usercombo, turn password -> base64(hmac(secret key,  usercombo)).   This  allows
              TURN  credentials  to  be  accounted  for  a specific user id.  If you don't have a
              suitable id, the timestamp alone can  be  used.   This  option  is  just  turns  on
              secret-based  authentication.   The actual value of the secret is defined either by
              option static-auth-secret, or  can  be  found  in  the  turn_secret  table  in  the
              database.   This option can be used with long-term credentials mechanisms only - it
              does not make much sense with the short-term mechanism.

       --dh566
              Use 566 bits predefined DH TLS key. Default size of the key is 1066.

       --dh2066
              Use 2066 bits predefined DH TLS key. Default size of the key is 1066.

       --no-sslv2
              Do not allow SSLv2 protocol.

       --no-sslv3
              Do not allow SSLv3 protocol.

       --no-tlsv1
              Do not allow TLSv1 protocol.

       --no-tlsv1_1
              Do not allow TLSv1.1 protocol.

       --no-tlsv1_2
              Do not allow TLSv1.2 protocol.

       --no-udp
              Do not start UDP client listeners.

       --no-tcp
              Do not start TCP client listeners.

       --no-tls
              Do not start TLS client listeners.

       --no-dtls
              Do not start DTLS client listeners.

       --no-udp-relay
              Do not allow UDP relay endpoints defined in RFC 5766, use only TCP relay  endpoints
              as defined in RFC 6062.

       --no-tcp-relay
              Do  not allow TCP relay endpoints defined in RFC 6062, use only UDP relay endpoints
              as defined in RFC 5766.

       --stale-nonce
              Use extra security with nonce value having limited lifetime (600 secs).

       --no-stdout-log
              Flag to prevent stdout log messages.  By default, all log  messages  are  going  to
              both  stdout  and  to  the configured log file. With this option everything will be
              going to the log file only (unless the log file itself is stdout).

       --syslog
              With this flag, all log will be redirected to the system log (syslog).

       --secure-stun
              Require authentication of the STUN Binding request.  By default,  the  clients  are
              allowed anonymous access to the STUN Binding functionality.

       -S, --stun-only
              Run  as  STUN  server  only, all TURN requests will be ignored.  Option to suppress
              TURN functionality, only STUN requests will be processed.

       --no-stun
              Run as TURN server only, all STUN requests will be  ignored.   Option  to  suppress
              STUN functionality, only TURN requests will be processed.

       --no-loopback-peers
              Disallow peers on the loopback addresses (127.x.x.x and ::1).

       --no-multicast-peers
              Disallow peers on well-known broadcast addresses (224.0.0.0 and above, and FFXX:*).

       --sha256
              Require  SHA256  digest function to be used for the message integrity.  By default,
              the server uses SHA1 hashes. With this option, the  server  requires  the  stronger
              SHA256  hashes.  The  client  application must support SHA256 hash function if this
              option is used. If the server obtains a message  from  the  client  with  a  weaker
              (SHA1) hash function then the server returns error code 426.

       --mobility
              Mobility with ICE (MICE) specs support.

       --no-cli
              Turn  OFF  the  CLI support. By default it is always ON.  See also options --cli-ip
              and --cli-port.

       --server-relay
              Server relay. NON-STANDARD AND DANGEROUS OPTION.  Only for those applications  when
              we  want to run server applications on the relay endpoints.  This option eliminates
              the IP permissions check on the packets  incoming  to  the  relay  endpoints.   See
              http://tools.ietf.org/search/rfc5766#section-17.2.3 .

       --udp-self-balance
              (recommended  for  older  Linuxes  only)  Automatically  balance  UDP  traffic over
              auxiliary servers (if configured). The load balancing is using the ALTERNATE-SERVER
              mechanism.  The  TURN  client  must  support 300 ALTERNATE-SERVER response for this
              functionality.

       -h     Help.

       Options with required values:

       -d, --listening-device
              Listener interface device.  (NOT RECOMMENDED. Optional functionality, Linux  only).
              The  turnserver process must have root privileges to bind the listening endpoint to
              a device. If turnserver must run as a process without root privileges, then just do
              not use this setting.

       -L, --listening-ip
              Listener  IP  address  of  relay  server.  Multiple listeners can be specified, for
              example: -L ip1 -L ip2 -L ip3 If no IP(s) specified, then all IPv4 and IPv6  system
              IPs  will  be used for listening.  The same ip(s) can be used as both listening and
              relay ip(s).

       -p, --listening-port
              TURN listener port for UDP and TCP listeners (Default: 3478).  Note: actually,  TLS
              &  DTLS  sessions can connect to the "plain" TCP & UDP port(s), too - if allowed by
              configuration.

       --tls-listening-port
              TURN listener port for TLS and DTLS listeners  (Default:  5349).   Note:  actually,
              "plain"  TCP & UDP sessions can connect to the TLS & DTLS port(s), too - if allowed
              by configuration. The TURN server "automatically" recognizes the type  of  traffic.
              Actually,  two  listening  endpoints  (the  "plain"  one  and  the  "tls"  one) are
              equivalent in terms of functionality; but we keep both endpoints to satisfy the RFC
              5766 specs.  For secure TCP connections, we currently support SSL version 3 and TLS
              versions 1.0, 1.1, 1.2. SSL2 "encapsulation mode" is also  supported.   For  secure
              UDP connections, we support DTLS version 1.

       --alt-listening-port
              Alternative listening port for UDP and TCP listeners; default (or zero) value means
              "listening port plus one".  This is needed for STUN CHANGE_REQUEST -  in  RFC  5780
              sense  or  in  old  RFC  3489  sense - for NAT behavior discovery). The TURN Server
              supports CHANGE_REQUEST only if it is started  with  more  than  one  listening  IP
              address  of the same family (IPv4 or IPv6). The CHANGE_REQUEST is only supported by
              UDP protocol, other protocols are listening on that endpoint only for "symmetry".

       --alt-tls-listening-port
              Alternative listening port for TLS and DTLS protocols.   Default  (or  zero)  value
              means "TLS listening port plus one".

       --aux-server
              Auxiliary  STUN/TURN  server listening endpoint.  Aux servers have almost full TURN
              and STUN functionality.  The (minor) limitations are:

              1)  Auxiliary servers do not have alternative ports and they do  not  support  STUN
                  RFC 5780 functionality (CHANGE REQUEST).

              2)  Auxiliary servers also are never returning ALTERNATIVE-SERVER reply.

       Valid  formats  are  1.2.3.4:5555  for  IPv4  and  [1:2::3:4]:5555 for IPv6.  There may be
       multiple aux-server options, each will be used for listening to client requests.

       -i, --relay-device
              Relay interface device for relay sockets (NOT RECOMMENDED. Optional, Linux only).

       -E, --relay-ip
              Relay address (the local IP address that will be used to relay the packets  to  the
              peer).  Multiple  relay  addresses may be used: -E ip1 -E ip2 -E ip3 The same IP(s)
              can be used as both listening IP(s) and relay IP(s).  If no relay IP(s)  specified,
              then  the  turnserver  will  apply  the default policy: it will decide itself which
              relay addresses to be used, and it will  always  be  using  the  client  socket  IP
              address as the relay IP address of the TURN session (if the requested relay address
              family is the same as the family of the client socket).

       -X, --external-ip
              TURN Server public/private address mapping, if the server is behind NAT.   In  that
              situation, if a -X is used in form "-X <ip>" then that ip will be reported as relay
              IP address of all allocations. This scenario works only in a simple case  when  one
              single  relay  address is be used, and no CHANGE_REQUEST functionality is required.
              That single relay address must  be  mapped  by  NAT  to  the  'external'  IP.   The
              "external-ip"  value,  if not empty, is returned in XOR-RELAYED-ADDRESS field.  For
              that 'external' IP, NAT must forward ports directly (relayed  port  12345  must  be
              always  mapped  to the same 'external' port 12345).  In more complex case when more
              than one IP address is involved, that option must be used several times, each entry
              must  have  form  "-X  <public-ip/private-ip>",  to  map  all  involved  addresses.
              CHANGE_REQUEST (RFC5780 or RFC3489) NAT  discovery  STUN  functionality  will  work
              correctly,  if  the addresses are mapped properly, even when the TURN server itself
              is behind A NAT.  By default, this value is empty, and no address mapping is used.

       -m, --relay-threads
              Number of relay threads to handle  the  established  connections  (in  addition  to
              authentication  thread and the listener thread).  If set to 0 then application runs
              relay process in a single thread, in the same thread with the listener process (the
              authentication  thread  will  still be a separate thread). In older systems (before
              Linux kernel 3.9), the number of UDP threads is  always  one  threads  per  network
              listening endpoint - unless "-m 0" or "-m 1" is set.

       --min-port
              Lower bound of the UDP port range for relay endpoints allocation.  Default value is
              49152, according to RFC 5766.

       --max-port
              Upper bound of the UDP port range for relay endpoints allocation.  Default value is
              65535, according to RFC 5766.

       -u, --user
              Long-term security mechanism credentials user account, in the column-separated form
              username:key.  Multiple user accounts may used in the command  line.   The  key  is
              either  the  user  password,  or  the key is generated by turnadmin command. In the
              second case, the key must be prepended with 0x symbols.  The key is calculated over
              the user name, the realm, and the user password.  This setting may not be used with
              TURN REST API or with short-term credentials mechanism.

       -r, --realm
              Realm to be used for all users. Must be used with long-term  credentials  mechanism
              or with TURN REST API.

       -C, --rest-api-separator
              This  is the username/timestamp separator symbol (character) in TURN REST API.  The
              default value is :.

       -q, --user-quota
              Per-user allocations quota: how many concurrent allocations a user can create.

       -Q, --total-quota
              Total allocations quota: global limit on concurrent allocations.

       --static-auth-secret
              Static authentication secret value (a string) for TURN REST API only.  If not  set,
              then the turn server will try to use the dynamic value in turn_secret table in user
              database (if present). The database-stored value can be  changed  on-the-fly  by  a
              separate  program,  so  this  is  why  that  other mode is dynamic. Multiple shared
              secrets can be used (both in the database and in the "static" fashion).

       -s, --max-bps
              Max bytes-per-second bandwidth a TURN session  is  allowed  to  handle  (input  and
              output  network  streams are treated separately). Anything above that limit will be
              dropped or temporary suppressed (within the available buffer limits).

       --cert Certificate  file,  PEM  format.  Same  file  search  rules  applied  as  for   the
              configuration file. If both --no-tls and --no-dtls options are specified, then this
              parameter is not needed.  Default value is turn_server_cert.pem.

       --pkey Private  key  file,  PEM  format.  Same  file  search  rules  applied  as  for  the
              configuration file. If both --no-tls and --no-dtls options are specified, then this
              parameter is not needed.  Default value is turn_server_pkey.pem.

       --pkey-pwd
              If the private key file is encrypted, then this password to be used.

       --cipher-list
              Allowed OpenSSL cipher list for TLS/DTLS connections.  Default value is "DEFAULT".

       --CA-file
              CA  file  in  OpenSSL  format.   Forces  TURN  server  to  verify  the  client  SSL
              certificates.   By  default,  no  CA  is  set  and  no  client certificate check is
              performed.

       --ec-curve-name
              Curve name for EC ciphers, if supported by OpenSSL library  (TLS  and  DTLS).   The
              default value is prime256v1.

       --dh-file
              Use  custom  DH  TLS  key,  stored  in  PEM  format in the file.  Flags --dh566 and
              --dh2066 are ignored when the DH key is taken from a file.

       -l, --log-file
              Option to set the full path name of the log file.  By default, the turnserver tries
              to open a log file in /var/log/turnserver, /var/log, /var/tmp, /tmp and . (current)
              directories (which file open operation succeeds first that file will be used). With
              this option you can set the definite log file name.  The special names are "stdout"
              and "-" - they will force everything  to  the  stdout.  Also,  "syslog"  name  will
              redirect  everything  into the system log (syslog), as if the option "--syslog" was
              set.

       --alternate-server
              Option to set the "redirection" mode. The value of this option will be the  address
              of  the alternate server for UDP & TCP service in form of <ip>[:<port>]. The server
              will send this value in the attribute ALTERNATE-SERVER, with error 300, on ALLOCATE
              request,  to  the  client.   Client  will receive only values with the same address
              family as the client network endpoint address family.  See RFC 5389  and  RFC  5766
              for  ALTERNATE-SERVER  functionality description.  The client must use the obtained
              value for subsequent TURN communications.   If  more  than  one  --alternate-server
              options  are  provided,  then the functionality can be more accurately described as
              "load-balancing" than a mere "redirection".  If the port number  is  omitted,  then
              the  default  port  number  3478 for the UDP/TCP protocols will be used.  Colon (:)
              characters in IPv6 addresses may  conflict  with  the  syntax  of  the  option.  To
              alleviate  this conflict, literal IPv6 addresses are enclosed in square brackets in
              such resource identifiers, for example: [2001:db8:85a3:8d3:1319:8a2e:370:7348]:3478
              .   Multiple  alternate  servers  can  be set. They will be used in the round-robin
              manner. All servers in the pool are considered of equal weight and the load will be
              distributed  equally. For example, if we have 4 alternate servers, then each server
              will receive 25% of ALLOCATE requests. An alternate TURN server address can be used
              more  than  one  time  with  the  alternate-server  option,  so  this  can  emulate
              "weighting" of the servers.

       --tls-alternate-server
              Option to set alternative server for TLS & DTLS services in form of <ip>:<port>. If
              the  port  number  is  omitted,  then the default port number 5349 for the TLS/DTLS
              protocols will be used. See the previous option for the functionality description.

       -O, --redis-statsdb
              Redis status and statistics database connection string, if used (default  -  empty,
              no Redis stats DB used). This database keeps allocations status information, and it
              can be also used  for  publishing  and  delivering  traffic  and  allocation  event
              notifications.   This  database  option can be used independently of --redis-userdb
              option, and  actually  Redis  can  be  used  for  status/statistics  and  MySQL  or
              PostgreSQL  can  be used for the user database.  The connection string has the same
              parameters as redis-userdb connection string.

       --max-allocate-timeout
              Max time, in seconds, allowed for full allocation  establishment.   Default  is  60
              seconds.

       --denied-peer-ip=<IPaddr[-IPaddr]>

       --allowed-peer-ip=<IPaddr[-IPaddr]>  Options  to  ban  or  allow  specific ip addresses or
       ranges of ip addresses. If an ip address is specified as both allowed and denied, then the
       ip  address is considered to be allowed. This is useful when you wish to ban a range of ip
       addresses, except for a few specific ips within that range.  This can be used when you  do
       not  want  users  of  the  turn server to be able to access machines reachable by the turn
       server, but would otherwise be unreachable from the internet (e.g. when the turn server is
       sitting  behind  a  NAT).  The  'white" and "black" peer IP ranges can also be dynamically
       changed in the database.  The allowed/denied addresses (white/black lists) rules are  very
       simple:

              1)  If there is no rule for an address, then it is allowed;

              2)  If  there  is  an  "allowed" rule that fits the address then it is allowed - no
                  matter what;

              3)  If there is no "allowed" rule that fits the address, and if there is a "denied"
                  rule that fits the address, then it is denied.

       --pidfile
              File  name to store the pid of the process.  Default is /var/run/turnserver.pid (if
              superuser account is used) or /var/tmp/turnserver.pid .

       --proc-user
              User name to run the process. After the initialization, the turnserver process will
              make an attempt to change the current user ID to that user.

       --proc-group
              Group  name  to  run  the process. After the initialization, the turnserver process
              will make an attempt to change the current group ID to that group.

       --cli-ip
              Local system IP address to be used for CLI management  interface.   The  turnserver
              process  can  be accessed for management with telnet, at this IP address and on the
              CLI port (see the next parameter).  Default value is 127.0.0.1. You can use  telnet
              or putty (in telnet mode) to access the CLI management interface.

       --cli-port
              CLI management interface listening port. Default is 5766.

       --cli-password
              CLI access password. Default is empty (no password).

       --cli-max-output-sessions
              Maximum  number  of  output  sessions in ps CLI command.  This value can be changed
              on-the-fly in CLI. The default value is 256.

       --ne=[1|2|3]
              Set network engine type for the process (for internal purposes).

       ==================================

LOAD BALANCE AND PERFORMANCE TUNING

       This topic is covered in the wiki page:

       http://code.google.com/p/rfc5766-turn-server/wiki/turn_performance_and_load_balance

       ===================================

WEBRTC USAGE

       This is a set of notes for the WebRTC users:

       1)  WebRTC uses long-term authentication mechanism, so you  have  to  use  -a  option  (or
           --lt-cred-mech).   WebRTC  relaying  will  not  work  with  anonymous  access  or with
           short-term authentication.  With -a option,  do  not  forget  to  set  the  realm  (-r
           option). You will also have to set up the user accounts, for that you have a number of
           options:

               a) command-line options (-u).

               b) userdb config file.

               c) a database table (PostgreSQL or MySQL). You will have to set keys with
               turnadmin utility (see docs and wiki for turnadmin). You cannot use open passwords
               in the database.

               d) Redis key/value pair(s), if Redis is used. You key use either keys or
               open passwords with Redis; see turndb/testredisdbsetup.sh file.

               e) You also can use the TURN REST API. You will need shared secret(s) set
               either  through the command line option, or through the config file, or through
               the database table or Redis key/value pairs.

       2)  Usually WebRTC uses fingerprinting (-f).

       3)  -v option may be nice to see the connected clients.

       4)  -X is needed if you are running your TURN server behind a NAT.

       5)  --min-port and --max-port may be needed if you want to limit the relay endpoints ports
           number range.

       ===================================

TURN REST API

       In  WebRTC,  the browser obtains the TURN connection information from the web server. This
       information is a secure information - because it contains the necessary TURN  credentials.
       As  these  credentials  are  transmitted  over  the  public  networks, we have a potential
       security breach.

       If we have to  transmit  a  valuable  information  over  the  public  network,  then  this
       information  has  to  have  a  limited lifetime. Then the guy who obtains this information
       without permission will be able to perform only limited damage.

       This is how the idea of TURN REST API - time-limited TURN  credentials  -  appeared.  This
       security mechanism is based upon the long-term credentials mechanism. The main idea of the
       REST API is that the web  server  provides  the  credentials  to  the  client,  but  those
       credentials  can  be  used  only  limited time by an application that has to create a TURN
       server connection.

       The "classic" long-term credentials mechanism (LTCM) is described here:

       http://tools.ietf.org/html/rfc5389#section-10.2
       http://tools.ietf.org/html/rfc5389#section-15.4

       For  authentication,  each  user  must know two things: the username and the password. The
       nonce and the realm values are supplied by the  TURN  server.   But  LTCM  is  not  saying
       anything  about  the nature and about the persistence of the username and of the password;
       and this is used by the REST API.

       In the TURN REST API, there is no persistent passwords for users.  A  user  has  just  the
       username.  The  password  is  always  temporary,  and  it  is  generated by the web server
       on-demand, when the user accesses the WebRTC page. And,  actually,  a  temporary  one-time
       session only, username is provided to the user, too.

       The temporary user is generated as:

       temporary-username="username" + ":" + "timestamp"

       where username is the persistent user name, and the timestamp format is just seconds sinse
       1970 - the same value as time(NULL) function returns.

       The temporary password is obtained as HMAC-SHA1 function over the temporary username, with
       shared secret as the HMAC key, and then the result is encoded:

       temporary-password = base64_encode(hmac-sha1(shared-secret, temporary-username))

       Both the TURN server and the web server know the same shared secret. How the shared secret
       is distributed among the involved entities is left to the WebRTC deployment details - this
       is beyond the scope of the TURN REST API.

       So,  a timestamp is used for the temporary password calculation, and this timestamp can be
       retrieved from the temporary username. This information is valuable, but  only  temporary,
       while  the  timestamp  is  not  expired.  Without  knowledge  of  the shared secret, a new
       temporary password cannot be generated.

       This is all formally described in Justin's Uberti TURN  REST  API  document  that  can  be
       obtained   following  the  link  "TURN  REST  API"  in  the  TURN  Server  project's  page
       http://code.google.com/p/rfc5766-turn-server/.

       Once the temporary username and password are obtained by the client (browser) application,
       then  the  rest is just 'classic" long-term credentials mechanism.  For developers, we are
       going to describe it step-by-step below:

              ·  a new TURN client sends a request command to the TURN server.

              ·  TURN server sees that this is a new client and the message is not authenticated.

              ·  the TURN server generates a random nonce string, and return the error 401 to the
                 client, with nonce and realm included.

              ·  the  client  sees  the  401  error  and  it  extracts  two values from the error
                 response: the nonce and the realm.

              ·  the client uses username, realm and password to produce a key:

                       key = MD5(username ":" realm ":" SASLprep(password))
              (SASLprep is described here: http://tools.ietf.org/html/rfc4013)

              ·  the client forms a new request, adds username, realm and nonce to  the  request.
                 Then, the client calculates and adds the integrity field to the request. This is
                 the trickiest part of the process, and it is described in  the  end  of  section
                 15.4: http://tools.ietf.org/html/rfc5389#section-15.4

              ·  the  client,  optionally,  adds the fingerprint field. This may be also a tricky
                 procedure, described in section 15.5 of the same document.  WebRTC usually  uses
                 fingerprinted TURN messages.

              ·  the TURN server receives the request, reads the username.

              ·  then  the TURN server checks that the nonce and the realm in the request are the
                 valid ones.

              ·  then the TURN server calculates the key.

              ·  then the TURN server calculates the integrity field.

              ·  then the TURN server compares the calculated integrity field with  the  received
                 one - they must be the same. If the integrity fields differ, then the request is
                 rejected.

       In subsequent communications, the client may go with exactly the same  sequence,  but  for
       optimization  usually  the  client,  having  already  information  about  realm and nonce,
       pre-calculates the integrity string for each request,  so  that  the  401  error  response
       becomes  unnecessary.   The TURN server may use "--stale-nonce" option for extra security:
       in some time, the nonce expires and the client will obtain 438 error response with the new
       nonce, and the client will have to start using the new nonce.

       In  subsequent  communications,  the  sever  and  the  client  will always assume the same
       password - the original password becomes the session parameter and is never  expiring.  So
       the  password is not changing while the session is valid and unexpired. So, if the session
       is properly maintained, it may go forever, even if the  user  password  has  been  already
       changed  (in the database). The session simply is using the old password. Once the session
       got disconnected, the client will have to use the  new  password  to  re-connect  (if  the
       password has been changed).

       An  example  when  a  new shared secret is generated every hour by the TURN server box and
       then   supplied   to   the   web   server,   remotely,   is   provided   in   the   script
       examples/scripts/restapi/shared_secret_maintainer.pl .

       A  very  important thing is that the nonce must be totally random and it must be different
       for different clients and different sessions.

       ===================================

DATABASES

       For the user database, the turnserver has the following options:

       1)  Users can be set in the command line, with multiple -u or --user options.   Obviously,
           only  a  few  users  can  be  set  that  way,  and their credentials are fixed for the
           turnserver process lifetime.

       2)  Users can be set in turnusers.conf flat file DB. The turnserver  process  periodically
           re-reads  this  file,  so  the  user  accounts  may be changed while the turnserver is
           running.  But still a relatively small (up to a hundred ?)  number  of  users  can  be
           handled that way.

       3)  Users  can  be  stored  in  PostgreSQL  database,  if the turnserver was compiled with
           PostgreSQL support. Each  time  turnserver  checks  user  credentials,  it  reads  the
           database  (asynchronously,  of  course,  so  that  the  current flow of packets is not
           delayed in any way), so any change in the database content is immediately  visible  by
           the  turnserver.  This is the way if you need the best scalability. The schema for the
           database can be found in schema.sql file.  For long-term credentials, you have to  set
           the  "keys"  for the users; the "keys" are generated by the turnadmin utility. For the
           key generation, you need username, password and the realm.  All users in the  database
           must  use  the  same realm value; if down the road you will decide to change the realm
           name, then you will have to re-generate all user keys (that can be  done  in  a  batch
           script).  If  you are using short-term credentials, then you use open passwords in the
           database; you will have to make sure that nobody can access the  database  outside  of
           the TURN server box.

       4)  The  same  is  true  for MySQL database. The same schema file is applicable.  The same
           considerations are applicable.

       5)  The same is true for the Redis database, but  the  Redis  database  has  aa  different
           schema  -  it can be found (in the form of explanation) in schema.userdb.redis.  Also,
           in Redis you can store both "keys" and open passwords (for long  term  credentials)  -
           the  "open  password"  option  is  less  secure  but  more convenient for low-security
           environments.  For short-term credentials, you will use open passwords only.  See  the
           file turndb/testredisdbsetup.sh as an example.

       6)  Of  course,  the  turnserver can be used in non-secure mode, when users are allowed to
           establish sessions anonymously. But in most cases (like WebRTC) that will not work.

       For the status and statistics database, there are two choices:

       1)  The simplest choice is not to use it. Do not  set  --redis-statsdb  option,  and  this
           functionality will be simply ignored.

       2)  If  you  choose  to  use it, then set the --redis-statsdb option. This may be the same
           database as in --redis-userdb option, or it may be a different database. You may  want
           to  use  different  database  for  security  or convenience reasons. Also, you can use
           different database management systems for the user database and  for  the  ststus  and
           statistics  database. For example, you can use MySQL as the user database, and you can
           use redis for the statistics. Or you can use Redis for both.

       So, we have 6  choices  for  the  user  management,  and  2  choices  for  the  statistics
       management.  These two are totally independent. So, you have overall 6*2=12 ways to handle
       persistent information, choose any for your convenience.

       You do not have to handle the database information "manually" - the turnadmin program  can
       handle  everything for you. For PostgreSQL and MySQL you will just have to create an empty
       database with schema.sql SQL script. With Redis, you do not have to do even  that  -  just
       run turnadmin and it will set the users for you (see the turnadmin manuals).

       =================================

LIBRARIES

       In the lib/ sub-directory the build process will create TURN client messaging library.  In
       the include/ sub-directory, the necessary include files will be placed.  The  C++  wrapper
       for the messaging functionality is located in TurnMsgLib.h header.  An example of C++ code
       can be found in stunclient.c file.

       =================================

DOCS

       After installation, run the command:

       $ man turnserver

       or in the project root directory:

       $ man -M man turnserver

       to see the man page.

       In the docs/html subdirectory of the original archive  tree,  you  will  find  the  client
       library    reference.    After    the    installation,    it    will    be    placed    in
       PREFIX/share/doc/turnserver/html.

       =================================

LOGS

       When the TURN Server starts, it makes efforts to create a log file turn_<pid>.log  in  the
       following directories:

              ·  /var/log

              ·  /log/

              ·  /var/tmp

              ·  /tmp

              ·  current directory

       If  all  efforts  failed (due to the system permission settings) then all log messages are
       sent only to the standard output of the process.

       This behavior can be controlled by --log-file, --syslog and --no-stdout-log options.

       =================================

TELNET CLI

       The turnserver process provides a telnet CLI access as  statistics  and  basic  management
       interface.  By  default,  the  turnserver starts a telnet CLI listener on IP 127.0.0.1 and
       port 5766. That can be changed by the command-cline options of the turnserver process (see
       --cli-ip  and  --cli-port  options).  The  full list of telnet CLI commands is provided in
       "help" command output in the telnet CLI.

       =================================

CLUSTERS

       TURN Server can be a part of the cluster installation. But, to  support  the  "even  port"
       functionality  (RTP/RTCP  streams  pairs) the client requests from a particular IP must be
       delivered to the same TURN Server instance, so it requires some networking setup massaging
       for  the cluster. The reason is that the RTP and RTCP relaying endpoints must be allocated
       on the same relay IP. It would be possible to design a scheme with  the  application-level
       requests forwarding (and we may do that later) but it would affect the performance.

       =================================

FILES

       /etc/turnserver.conf

       /etc/turnuserdb.conf

       /usr/local/etc/turnserver.conf

       /usr/local/etc/turnuserdb.conf

       =================================

DIRECTORIES

       /usr/local/share/turnserver

       /usr/local/share/doc/turnserver

       /usr/local/share/examples/turnserver

       =================================

STANDARDS

       obsolete STUN RFC 3489

       new STUN RFC 5389

       TURN RFC 5766

       TURN-TCP extension RFC 6062

       TURN IPv6 extension RFC 6156

       STUN/TURN test vectors RFC 5769

       STUN NAT behavior discovery RFC 5780

       =================================

SEE ALSO

       turnadmin, turnutils

       ======================================

   WEB RESOURCES
       project page:

       http://code.google.com/p/rfc5766-turn-server/

       Wiki page:

       http://code.google.com/p/rfc5766-turn-server/wiki/Readme

       forum:

       https://groups.google.com/forum/?fromgroups=#!forum/turn-server-project-rfc5766-turn-server/

       ======================================

   AUTHORS
       Oleg Moskalenko <mom040267@gmail.com>

       Gabor Kovesdan http://kovesdan.org/

       Daniel Pocock http://danielpocock.com/

       John Selbie (jselbie@gmail.com)

       Lee Sylvester <lee@designrealm.co.uk>

       Erik Johnston <erikj@openmarket.com>

       Roman Lisagor <roman@demonware.net>

       Vladimir Tsanev <tsachev@gmail.com>

       Po-sheng Lin <personlin118@gmail.com>

       Peter Dunkley <peter.dunkley@crocodilertc.net>

       Mutsutoshi Yoshimoto <mutsutoshi.yoshimoto@mixi.co.jp>

                                          28 March 2014                                   TURN(1)