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Diffstat (limited to 'openvpn/management/management-notes.txt')
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diff --git a/openvpn/management/management-notes.txt b/openvpn/management/management-notes.txt new file mode 100644 index 0000000..06fc8c1 --- /dev/null +++ b/openvpn/management/management-notes.txt @@ -0,0 +1,436 @@ +OpenVPN Management Interface Notes +---------------------------------- + +The OpenVPN Management interface allows OpenVPN to +be administratively controlled from an external program via +a TCP socket. + +The interface has been specifically designed for GUI developers +and those who would like to programmatically or remotely control +an OpenVPN daemon. + +The management interface is implemented using a client/server TCP +connection, where OpenVPN will listen on a provided IP address +and port for incoming management client connections. + +The management protocol is currently cleartext without an explicit +security layer. For this reason, it is recommended that the +management interface either listen on localhost (127.0.0.1) +or on the local VPN address. It's possible to remotely connect +to the management interface over the VPN itself, though some +capabilities will be limited in this mode, such as the ability +to provide private key passwords. + +Future versions of the management interface may allow out-of-band +connections (i.e. not over the VPN) and secured with SSL/TLS. + +The management interface is enabled in the OpenVPN +configuration file using the following directives: + +--management +--management-query-passwords +--management-log-cache + +See the man page for documentation on these directives. + +Once OpenVPN has started with the management layer enabled, +you can telnet to the management port (make sure to use +a telnet client which understands "raw" mode). + +Once connected to the management port, you can use +the "help" command to list all commands. + +COMMAND -- echo +--------------- + +The echo capability is used to allow GUI-specific +parameters to be either embedded in the OpenVPN config file +or pushed to an OpenVPN client from a server. + +Command examples: + + echo on -- turn on real-time notification of echo messages + echo all -- print the current echo history list + echo off -- turn off real-time notification of echo messages + echo on all -- atomically enable real-time notification, + plus show any messages in history buffer + +For example, suppose you are developing a OpenVPN GUI and +you want to give the OpenVPN server the ability to ask +the GUI to forget any saved passwords. + +In the OpenVPN server config file, add: + + push "echo forget-passwords" + +When the OpenVPN client receives its pulled list of directives +from the server, the "echo forget-passwords" directive will +be in the list, and it will cause the management interface +to save the "forget-passwords" string in its list of echo +parameters. + +The management client can use "echo all" to output the full +list of echoed parameters, "echo on" to turn on real-time +notification of echoed parameters via the ">ECHO:" prefix, +or "echo off" to turn off real-time notification. + +When the GUI connects to the OpenVPN management socket, it +can issue an "echo all" command, which would produce output +like this: + + 1101519562,forget-passwords + END + +Essentially the echo command allowed us to pass parameters from +the OpenVPN server to the OpenVPN client, and then to the +management client (such as a GUI). The large integer is the +unix date/time when the echo parameter was received. + +If the management client had issued the command "echo on", +it would have enabled real-time notifications of echo +parameters. In this case, our "forget-passwords" message +would be output like this: + + >ECHO:1101519562,forget-passwords + +Like the log command, the echo command can atomically show +history while simultaneously activating real-time updates: + + echo on all + +The size of the echo buffer is currently hardcoded to 100 +messages. + +COMMAND -- exit, quit +--------------------- + +Close the managment session, and resume listening on the +management port for connections from other clients. Currently, +the OpenVPN daemon can at most support a single management client +any one time. + +COMMAND -- help +--------------- + +Print a summary of commands. + +COMMAND -- hold +--------------- + +The hold command can be used to manipulate the hold flag, +or release OpenVPN from a hold state. + +If the hold flag is set on initial startup or +restart, OpenVPN will hibernate prior to initializing +the tunnel until the management interface receives +a "hold release" command. + +The --management-hold directive of OpenVPN can be used +to start OpenVPN with the hold flag set. + +The hold flag setting is persistent and will not +be reset by restarts. + +OpenVPN will indicate that it is in a hold state by +sending a real-time notification to the management +client: + + >HOLD:Waiting for hold release + +Command examples: + + hold -- show current hold flag, 0=off, 1=on. + hold on -- turn on hold flag so that future restarts + will hold. + hold off -- turn off hold flag so that future restarts will + not hold. + hold release -- leave hold state and start OpenVPN, but + do not alter the current hold flag setting. + +COMMAND -- kill +--------------- + +In server mode, kill a particlar client instance. + +Command examples: + + kill Test-Client -- kill the client instance having a + common name of "Test-Client". + kill 1.2.3.4:4000 -- kill the client instance having a + source address and port of 1.2.3.4:4000 + +Use the "status" command to see which clients are connected. + +COMMAND -- log +-------------- + +Show the OpenVPN log file. Only the most recent n lines +of the log file are cached by the management interface, where +n is controlled by the OpenVPN --management-log-cache directive. + +Command examples: + + log on -- Enable real-time output of log messages. + log all -- Show currently cached log file history. + log on all -- Atomically show all currently cached log file + history then enable real-time notification of + new log file messages. + log off -- Turn off real-time notification of log messages. + log 20 -- Show the most recent 20 lines of log file history. + +Real-time notification format: + +Real-time log messages begin with the ">LOG:" prefix followed +by the following comma-separated fields: + + (a) unix integer date/time, + (b) zero or more message flags in a single string: + I -- informational + F -- fatal error + N -- non-fatal error + W -- warning + D -- debug, and + (c) message text. + +COMMAND -- mute +--------------- + +Change the OpenVPN --mute parameter. The mute parameter is +used to silence repeating messages of the same message +category. + +Command examples: + + mute 40 -- change the mute parameter to 40 + mute -- show the current mute setting + +COMMAND -- net +-------------- + +(Windows Only) Produce output equivalent to the OpenVPN +--show-net directive. The output includes OpenVPN's view +of the system network adapter list and routing table based +on information returned by the Windows IP helper API. + +COMMAND -- password and username +-------------------------------- + + The password command is used to pass passwords to OpenVPN. + + If OpenVPN is run with the --management-query-passwords + directive, it will query the management interface for RSA + private key passwords and the --auth-user-pass + username/password. + + When OpenVPN needs a password from the management interface, + it will produce a real-time ">PASSWORD:" message. + + Example 1: + + >PASSWORD:Need 'Private Key' password + + OpenVPN is indicating that it needs a password of type + "Private Key". + + The management client should respond to this query as follows: + + password "Private Key" foo + + Example 2: + + >PASSWORD:Need 'Auth' username/password + + OpenVPN needs a --auth-user-pass password. The management + client should respond: + + username "Auth" foo + password "Auth" bar + + The username/password itself can be in quotes, and special + characters such as double quote or backslash must be escaped, + for example, + + password "Private Key" "foo\"bar" + + The escaping rules are the same as for the config file. + See the "Command Parsing" section below for more info. + + The PASSWORD real-time message type can also be used to + indicate password or other types of authentication failure: + + Example 3: The private key password is incorrect and OpenVPN + is exiting: + + >PASSWORD:Verification Failed: 'Private Key' + + Example 4: The --auth-user-pass username/password failed, + and OpenVPN is exiting: + + >PASSWORD:Verification Failed: 'Auth' + +COMMAND -- signal +----------------- + +The signal command will send a signal to the OpenVPN daemon. +The signal can be one of SIGHUP, SIGTERM, SIGUSR1, or SIGUSR2. + +Command example: + + signal SIGUSR1 -- send a SIGUSR1 signal to daemon + +COMMAND -- state +---------------- + +Show the current OpenVPN state, show state history, or +enable real-time notification of state changes. + +These are the OpenVPN states: + +CONNECTING -- OpenVPN's initial state. +WAIT -- (Client only) Waiting for initial response + from server. +AUTH -- (Client only) Authenticating with server. +GET_CONFIG -- (Client only) Downloading configuration options + from server. +ASSIGN_IP -- Assigning IP address to virtual network + interface. +ADD_ROUTES -- Adding routes to system. +CONNECTED -- Initialization Sequence Completed. +RECONNECTING -- A restart has occurred. +EXITING -- A graceful exit is in progress. + +Command examples: + + state -- Print current OpenVPN state. + state on -- Enable real-time notification of state changes. + state off -- Disable real-time notification of state changes. + state all -- Print current state history. + state 3 -- Print the 3 most recent state transitions. + state on all -- Atomically show state history while at the + same time enable real-time state notification + of future state transitions. + +The output format consists of 4 comma-separated parameters: + (a) the integer unix date/time, + (b) the state name, + (c) optional descriptive string (used mostly on RECONNECTING + and EXITING to show the reason for the disconnect), and + (d) optional TUN/TAP local IP address (shown for ASSIGN_IP + and CONNECTED). + +Real-time state notifications will have a ">STATE:" prefix +prepended to them. + +COMMAND -- status +----------------- + +Show current daemon status information, in the same format as +that produced by the OpenVPN --status directive. + +Command examples: + +status -- Show status information using the default status + format version. + +status 2 -- Show status information using status format version 2. + +COMMAND -- username +------------------- + +See the "password" section above. + +COMMAND -- verb +--------------- + +Change the OpenVPN --verb parameter. The verb parameter +controls the output verbosity, and may range from 0 (no output) +to 15 (maximum output). See the OpenVPN man page for additional +info on verbosity levels. + +Command examples: + + verb 4 -- change the verb parameter to 4 + mute -- show the current verb setting + +COMMAND -- version +------------------ + +Show the current OpenVPN and Management Interface versions. + + +COMMAND -- auth-retry +--------------------- + +Set the --auth-retry setting to control how OpenVPN responds to +username/password authentication errors. See the manual page +for more info. + +Command examples: + + auth-retry interact -- Don't exit when bad username/passwords are entered. + Query for new input and retry. + +OUTPUT FORMAT +------------- + +(1) Command success/failure indicated by "SUCCESS: [text]" or + "ERROR: [text]". + +(2) For commands which print multiple lines of output, + the last line will be "END". + +(3) Real-time messages will be in the form ">[source]:[text]", + where source is "ECHO", "FATAL", "HOLD", "INFO", "LOG", + "PASSWORD", or "STATE". + +REAL-TIME MESSAGE FORMAT +------------------------ + +The OpenVPN management interface produces two kinds of +output: (a) output from a command, or (b) asynchronous, +real-time output which can be generated at any time. + +Real-time messages start with a '>' character in the first +column and are immediately followed by a type keyword +indicating the type of real-time message. The following +types are currently defined: + +ECHO -- Echo messages as controlled by the "echo" command. + +FATAL -- A fatal error which is output to the log file just + prior to OpenVPN exiting. + +HOLD -- Used to indicate that OpenVPN is in a holding state + and will not start until it receives a + "hold release" command. + +INFO -- Informational messages such as the welcome message. + +LOG -- Log message output as controlled by the "log" command. + +PASSWORD -- Used to tell the management client that OpenVPN + needs a password, also to indicate password + verification failure. + +STATE -- Shows the current OpenVPN state, as controlled + by the "state" command. + +Command Parsing +--------------- + +OpenVPN uses the same command line lexical analyzer as is used +by the OpenVPN config file parser. + +Whitespace is a parameter separator. + +Double quotation characters ("") can be used to enclose +parameters containing whitespace + +Backslash-based shell escaping is performed, using the following +mappings + +\\ Maps to a single backslash character (\). +\" Pass a literal doublequote character ("), don't + interpret it as enclosing a parameter. +\[SPACE] Pass a literal space or tab character, don't + interpret it as a parameter delimiter. |