identifying the type of command or response contained. Keywords in
client commands are not case-sensitive; the server always uses uppercase
for its keywords.
-.SS "Server responses"
-For client command, the server responds with zero or more
+.SS "Simple commands"
+For simple client command, the server responds with zero or more
.B INFO
lines, followed by either an
.B OK
code is followed by a machine-readable explanation of why the command
failed.
.PP
-In addition, there are three types of asynchronous messages which
-aren't associated with any particular command. The
+Simple command processing is strictly synchronous: the server reads a
+command, processes it, and responds, before reading the next command.
+All commands can be run as simple commands. Long-running commands
+(e.g.,
+.B ADD
+and
+.BR PING )
+block the client until they finish, but the rest of the server continues
+running.
+.SS "Asynchronous messages"
+There are three types of asynchronous messages which
+aren't associated with any particular command.
+.PP
+The
.B WARN
message contains a machine-readable message warning of an error
encountered while processing a command, unexpected or unusual behaviour
by a peer, or a possible attack by an adversary. Under normal
-conditions, the server shouldn't emit any warnings. The
+conditions, the server shouldn't emit any warnings.
+.PP
+The
.B TRACE
message contains a human-readable tracing message containing diagnostic
information. Trace messages are controlled using the
.B TRACE
administration command (see below). Support for tracing can be disabled
when the package is being configured, and may not be available in your
-version. Finally, the
+version.
+.PP
+Finally, the
.B NOTE
message is a machine-readable notification about some routine but
interesting event such as creation or destruction of peers.
The presence of asynchronous messages can be controlled using the
.B WATCH
command.
+.SS "Background commands"
+Some commands (e.g.,
+.B ADD
+and
+.BR PING )
+take a long time to complete. To prevent these long-running commands
+from tying up a server connection, they can be run in the background.
+Not all commands can be run like this: the ones that can provide a
+.B \-background
+option, which must be supplied with a
+.IR tag .
+.PP
+A command may fail before it starts running in the background. In this
+case, the server emits a
+.B FAIL
+response, as usual. To indicate that a command has started running in
+the background, the server emits a response of the form
+.BI "BGDETACH " tag \fR,
+where
+.I tag
+is the value passed to the
+.B \-background
+option. From this point on, the server is ready to process more
+commands and reply to them.
+.PP
+Responses to background commands are indicated by a line beginning with
+one of the tokens
+.BR BGOK ,
+.BR BGFAIL ,
+or
+.BR BGINFO ,
+followed by the command tag. These correspond to the
+.BR OK ,
+.BR FAIL ,
+and
+.B INFO
+responses for simple commands:
+.B BGINFO
+indicates information from a background command which has not completed
+yet; and
+.B BGOK
+and
+.B BGFAIL
+indicates that a background command succeeded or failed, respectively.
+.PP
+A background command will never issue an
+.B OK
+response: it will always detach and then issue a
+.B BGOK
+response.
.SS "Network addresses"
A network address is a sequence of words. The first is a token
identifying the network address family. The length of an address and
be contacted. The following options are recognised.
.RS
.TP
-.BI "-tunnel " tunnel
+.BI "\-background " tag
+Run the command in the background, using the given
+.IR tag .
+.TP
+.BI "\-keepalive " time
+Send a no-op packet if we've not sent a packet to the peer in the last
+.I time
+interval. This is useful for persuading port-translating firewalls to
+believe that the `connection' is still active. The
+.I time
+is expressed as a nonnegative integer followed optionally by
+.BR d ,
+.BR h ,
+.BR m ,
+or
+.BR s
+for days, hours, minutes, or seconds respectively; if no suffix is
+given, seconds are assumed.
+.TP
+.BI "\-tunnel " tunnel
Use the named tunnel driver, rather than the default.
.RE
.TP
Causes the server to disassociate itself from its terminal and become a
background task. This only works once. A warning is issued.
.TP
+.BI "EPING \fR[" options "\fR] " peer
+Sends an encrypted ping to the peer, and expects an encrypted response.
+This checks that the peer is running (and not being impersonated), and
+that it can encrypt and decrypt packets correctly. Options and
+responses are the same as for the
+.B PING
+command.
+.TP
+.BI "FORCEKX " peer
+Requests the server to begin a new key exchange with
+.I peer
+immediately.
+.TP
.B "HELP"
Causes the server to emit an
.B INFO
.B USER
notification to all interested administration clients.
.TP
+.BI "PING \fR[" options "\fR] " peer
+Send a transport-level ping to the peer. The ping and its response are
+not encrypted or authenticated. This command, possibly in conjunction
+with tracing, is useful for ensuring that UDP packets are actually
+flowing in both directions. See also the
+.B EPING
+command.
+.IP
+An
+.B INFO
+line is printed describing the outcome:
+.RS
+.TP
+.BI "ping-ok " millis
+A response was received
+.I millis
+after the ping was sent.
+.TP
+.BI "ping-timeout"
+No response was received within the time allowed.
+.TP
+.BI "ping-peer-died"
+The peer was killed (probably by another admin connection) before a
+response was received.
+.RE
+.IP
+Options recognized for this command are:
+.RS
+.TP
+.BI "\-background " tag
+Run the command in the background, using the given
+.IR tag .
+.TP
+.BI "\-timeout " time
+Wait for
+.I time
+seconds before giving up on a response. The default is 5 seconds. (The
+time format is the same as for the
+.B "ADD \-keepalive"
+option.)
+.RE
+.TP
.B "PORT"
Emits an
.B INFO
server. If you've allowed your server to allocate a port dynamically,
this is how to find out which one it chose.
.TP
+.B "RELOAD"
+Instructs the server to recheck its keyring files. The server checks
+these periodically anyway but it may be necessary to force a recheck,
+for example after adding a new peer key.
+.TP
.B "QUIT"
Instructs the server to exit immediately. A warning is sent.
.TP
.SH "ERROR MESSAGES"
The following
.B FAIL
+(or
+.BR BGFAIL )
messages are sent to clients as a result of errors during command
processing.
.TP
(For any command.) The command couldn't be understood: e.g., the number
of arguments was wrong.
.TP
+.BI "bad-time-spec " word
+The
+.I word
+is not a valid time interval specification. Acceptable time
+specifications are nonnegative integers followed optionally by
+.BR d ,
+.BR h ,
+.BR m ,
+or
+.BR s ,
+for days, hours, minutes, or seconds, respectively.
+.TP
.BI "bad-trace-option " char
(For
.BR TRACE .)
There is already a peer named
.IR peer .
.TP
+.B "ping-send-failed"
+The attempt to send a ping packet failed, probably due to lack of
+encryption keys.
+.TP
.BI "resolve-error " hostname
(For
.BR ADD .)
.RB ` \- '
if none is relevant.
.TP
-.BI "PEER \- unexpected-source " address\fR...
-A packet arrived from
-.I address
-(a network address \(en see above), but no peer is known at that
-address. This may indicate a misconfiguration, or simply be a result of
-one end of a connection being set up before the other.
-.TP
.BI "PEER " peer " bad-packet no-type"
An empty packet arrived. This is very strange.
.TP
(in hex) isn't understood. Probably a strange random packet from
somewhere; could be an unlikely bug.
.TP
+.BI "PEER " peer " corrupt-encrypted-ping"
+The peer sent a ping response which matches an outstanding ping, but its
+payload is wrong. There's definitely a bug somewhere.
+.TP
+.BI "PEER " peer " corrupt-transport-ping"
+The peer (apparently) sent a ping response which matches an outstanding
+ping, but its payload is wrong. Either there's a bug, or the bad guys
+are playing tricks on you.
+.TP
.BI "PEER " peer " decrypt-failed"
An encrypted IP packet failed to decrypt. It may have been mangled in
transit, or may be a very old packet from an expired previous session
successive session keys, so this shouldn't occur unless the key exchange
takes ages or fails.
.TP
+.BI "PEER " peer " malformed-encrypted-ping"
+The peer sent a ping response which is hopelessly invalid. There's
+definitely a bug somewhere.
+.TP
+.BI "PEER " peer " malformed-transport-ping"
+The peer (apparently) sent a ping response which is hopelessly invalid.
+Either there's a bug, or the bad guys are playing tricks on you.
+.TP
.BI "PEER " peer " packet-build-failed"
There wasn't enough space in our buffer to put the packet we wanted to
send. Shouldn't happen.
.BI "PEER " peer " socket-write-error \-\- " message
An error occurred attempting to send a network packet. We lost that
one.
+.TP
+.BI "PEER " peer " unexpected-encrypted-ping 0x" id
+The peer sent an encrypted ping response whose id doesn't match any
+outstanding ping. Maybe it was delayed for longer than the server was
+willing to wait, or maybe the peer has gone mad.
+.TP
+.BI "PEER \- unexpected-source " address\fR...
+A packet arrived from
+.I address
+(a network address \(en see above), but no peer is known at that
+address. This may indicate a misconfiguration, or simply be a result of
+one end of a connection being set up before the other.
+.TP
+.BI "PEER " peer " unexpected-transport-ping 0x" id
+The peer (apparently) sent a transport ping response whose id doesn't
+match any outstanding ping. Maybe it was delayed for longer than the
+server was willing to wait, or maybe the peer has gone mad; or maybe
+there are bad people trying to confuse you.
.SS "SERVER warnings"
These indicate problems concerning the server process as a whole.
.TP
~mdw / tripe / blobdiff