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+.\" manual page [] for pppd 2.0
+.\" $Id: pppd.8,v 1.7 1994/06/09 01:50:48 paulus Exp $
+.\" SH section heading
+.\" SS subsection heading
+.\" LP paragraph
+.\" IP indented paragraph
+.\" TP hanging label
+.TH PPPD 8
+.SH NAME
+pppd \- Point to Point Protocol daemon
+.SH SYNOPSIS
+.B pppd
+[
+.I options
+] [
+.I tty_name
+] [
+.I speed
+]
+.SH DESCRIPTION
+.LP
+The Point-to-Point Protocol (PPP) provides a method for transmitting
+datagrams over serial point-to-point links.  PPP
+is composed of three parts: a method for encapsulating datagrams over
+serial links, an extensible Link Control Protocol (LCP), and
+a family of Network Control Protocols (NCP) for establishing
+and configuring different network-layer protocols.
+.LP
+The encapsulation scheme is provided by driver code in the kernel.
+.B pppd
+provides the basic LCP, authentication support, and an
+NCP for establishing and configuring the Internet Protocol (IP)
+(called the IP Control Protocol, IPCP).
+.SH FREQUENTLY USED OPTIONS
+.TP
+.I <tty_name>
+Communicate over the named device.  The string "/dev/"
+is prepended if necessary.  If no device name is given,
+.I pppd
+will use the controlling terminal, and will not fork to put itself in
+the background.
+.TP
+.I <speed>
+Set the baud rate to <speed>.  On systems such as 4.4BSD and NetBSD,
+any speed can be specified.  Other systems (e.g. SunOS) allow only a
+limited set of speeds.
+.TP
+.B asyncmap \fI<map>
+Set the async character map to <map>.
+This map describes which control characters cannot be successfully
+received over the serial line.
+.I pppd
+will ask the peer to send these characters as a 2-byte escape sequence.
+The argument is a 32 bit hex number
+with each bit representing a character to escape. 
+Bit 0 (00000001) represents the character 0x00;
+bit 31 (80000000) represents the character 0x1f or ^_.
+If multiple \fBasyncmap\fR options are
+given, the values are ORed together.
+If no \fBasyncmap\fR option is given, no async character map will be
+negotiated for the receive direction; the peer will then escape
+\fIall\fR control characters.
+.TP
+.B auth
+Require the peer to authenticate itself before allowing network
+packets to be sent or received.
+.TP
+.B connect \fI<p>
+Use the executable or shell command specified by \fI<p>\fR to set up the
+serial line.  This script would typically use the "chat" program to
+dial the modem and start the remote ppp session.
+.TP
+.B crtscts
+Use hardware flow control (i.e. RTS/CTS) to control the flow of data on
+the serial port.
+.TP
+.B xonxoff
+Use software flow control (i.e. XON/XOFF) to control the flow of data on
+the serial port.  This option is not implemented on BSD or Ultrix systems
+at present.
+.TP
+.B -crtscts
+A synonym for \fBxonxoff\fR.
+.TP
+.B defaultroute
+Add a default route to the system routing tables, using the peer as
+the gateway, when IPCP negotiation is successfully completed.
+This entry is removed when the PPP connection is broken.
+.TP
+.B disconnect \fI<p>
+Run the executable or shell command specified by \fI<p>\fR after
+\fIpppd\fR has terminated the link.  This script could, for example,
+issue commands to the modem to cause it to hang up if hardware modem
+control signals were not available.
+.TP
+.B escape \fIxx,yy,...
+Specifies that certain characters should be escaped on transmission
+(regardless of whether the peer requests them to be escaped with its
+async control character map).  The characters to be escaped are
+specified as a list of hex numbers separated by commas.  Note that
+almost any character can be specified for the \fBescape\fR option,
+unlike the \fBasyncmap\fR option which only allows control characters
+to be specified.  The characters which may not be escaped are those
+with hex values 0x20 - 0x3f or 0x5e.
+.TP
+.B file \fI<f>
+Read options from file <f> (the format is described below).
+.TP
+.B lock
+Specifies that \fIpppd\fR should use a UUCP-style lock on the serial
+device to ensure exclusive access to the device.
+.TP
+.B mru \fI<n>
+Set the MRU [Maximum Receive Unit] value to <n> for negotiation.
+.I pppd
+will ask the peer to send packets of no more than <n> bytes.
+The minimum MRU value is 128. 
+The default MRU value is 1500.  A value of 296 is recommended for slow
+links (40 bytes for TCP/IP header + 256 bytes of data).
+.TP
+.B netmask \fI<n>
+Set the interface netmask to <n>, a 32 bit netmask in "decimal dot" notation
+(e.g. 255.255.255.0).
+.TP
+.B passive
+Enables the "passive" option in the LCP.  With this option,
+.I pppd
+will attempt to initiate a connection; if no reply is received from
+the peer,
+.I pppd
+will then just wait passively for a valid LCP packet from the peer
+(instead of exiting, as it does without this option).
+.TP
+.B silent
+With this option,
+.I pppd
+will not transmit LCP packets to initiate a connection until a valid
+LCP packet is received from the peer (as for the "passive" option with
+old versions of \fIpppd\fR).
+.SH OPTIONS
+.TP
+.I <local_IP_address>\fB:\fI<remote_IP_address>
+Set the local and/or remote interface IP addresses.  Either one may be
+omitted.  The IP addresses can be specified with a host name or in
+decimal dot notation (e.g. 150.234.56.78).  The default local
+address is the (first) IP address of the system (unless the
+.B noipdefault
+option is given).  The remote address will be obtained from the peer
+if not specified in any option.  Thus, in simple cases, this option is
+not required.
+If a local and/or remote IP address is specified with this option,
+.I pppd
+will not accept a different value from the peer in the IPCP
+negotiation, unless the
+.B ipcp-accept-local
+and/or
+.B ipcp-accept-remote
+options are given, respectively.
+.TP
+.B -all
+Don't request or allow negotiation of any options for LCP and IPCP (use
+default values).
+.TP
+.B -ac
+Disable Address/Control compression negotiation (use default, i.e.
+address/control field disabled).
+.TP
+.B -am
+Disable asyncmap negotiation (use the default asyncmap, i.e. escape
+all control characters).
+.TP
+.B -as \fI<n>
+Same as
+.B asyncmap \fI<n>
+.TP
+.B -d
+Increase debugging level (same as the \fBdebug\fR option).
+.TP
+.B -detach
+Don't fork to become a background process (otherwise
+.I pppd
+will do so if a serial device is specified).
+.TP
+.B -ip
+Disable IP address negotiation (with this option, the remote IP
+address must be specified with an option on the command line or in an
+options file).
+.TP
+.B -mn
+Disable magic number negotiation.  With this option,
+.I pppd
+cannot detect a looped-back line.
+.TP
+.B -mru
+Disable MRU [Maximum Receive Unit] negotiation (use default, i.e. 1500).
+.TP
+.B -p
+Same as the
+.B passive
+option.
+.TP
+.B -pc
+Disable protocol field compression negotiation (use default, i.e.
+protocol field compression disabled).
+.TP
+.B +ua \fI<p>
+Agree to authenticate using PAP [Password Authentication Protocol] if
+requested by the peer, and
+use the data in file <p> for the user and password to send to the
+peer. The file contains the remote user name, followed by a newline,
+followed by the remote password, followed by a newline.  This option
+is obsolescent.
+.TP
+.B +pap
+Require the peer to authenticate itself using PAP.
+.TP
+.B -pap
+Don't agree to authenticate using PAP.
+.TP
+.B +chap
+Require the peer to authenticate itself using CHAP [Cryptographic
+Handshake Authentication Protocol] authentication.
+.TP
+.B -chap
+Don't agree to authenticate using CHAP.
+.TP
+.B -vj
+Disable negotiation of Van Jacobson style IP header compression (use
+default, i.e. no compression).
+.TP
+.B debug
+Increase debugging level (same as \fB\-d\fR).
+If this
+option is given, \fIpppd\fR will log the contents of all control
+packets sent or received in a readable form.  The packets are logged
+through syslog with facility \fIdaemon\fR and level \fIdebug\fR.  This
+information can be directed to a file by setting up /etc/syslog.conf
+appropriately (see syslog.conf(5)).  (If \fIpppd\fR is compiled with
+extra debugging enabled, it will log messages using facility
+\fIlocal2\fR instead of \fIdaemon\fR).
+.TP
+.B domain \fI<d>
+Append the domain name <d> to the local host name for authentication
+purposes.  For example, if gethostname() returns the name porsche, but the
+fully qualified domain name is porsche.Quotron.COM, you would use the
+domain option to set the domain name to Quotron.COM.
+.TP
+.B modem
+Use the modem control lines.  On Ultrix, this option implies hardware
+flow control, as for the \fBcrtscts\fR option.  (This option is not fully
+implemented.)
+.TP
+.B kdebug \fIn
+Enable debugging code in the kernel-level PPP driver.  The argument
+\fIn\fR is a number which is the sum of the following values: 1 to
+enable general debug messages, 2 to request that the contents of
+received packets be printed, and 4 to request that the contents of
+transmitted packets be printed.
+.TP
+.B local
+Don't use the modem control lines.
+.TP
+.B mtu \fI<n>
+Set the MTU [Maximum Transmit Unit] value to \fI<n>\fR.  Unless the
+peer requests a smaller value via MRU negotiation, \fIpppd\fR will
+request that the kernel networking code send data packets of no more
+than \fIn\fR bytes through the PPP network interface. 
+.TP
+.B name \fI<n>
+Set the name of the local system for authentication purposes to <n>.
+.TP
+.B user \fI<u>
+Set the user name to use for authenticating this machine with the peer
+using PAP to <u>.
+.TP
+.B usehostname
+Enforce the use of the hostname as the name of the local system for
+authentication purposes (overrides the
+.B name
+option).
+.TP
+.B remotename \fI<n>
+Set the assumed name of the remote system for authentication purposes
+to <n>.
+.TP
+.B proxyarp
+Add an entry to this system's ARP [Address Resolution Protocol] table
+with the IP address of the peer and the Ethernet address of this
+system.
+.TP
+.B login
+Use the system password database for authenticating the peer using
+PAP.
+.TP
+.B noipdefault
+Disables the default behaviour when no local IP address is specified,
+which is to determine (if possible) the local IP address from the
+hostname.  With this option, the peer will have to supply the local IP
+address during IPCP negotiation (unless it specified explicitly on the
+command line or in an options file).
+.TP
+.B lcp-echo-interval \fI<n>
+If this option is given, \fIpppd\fR will send an LCP echo-request
+frame to the peer every \fIn\fR seconds.  Under Linux, the
+echo-request is sent when no packets have been received from the peer
+for \fIn\fR seconds.  Normally the peer should respond to the
+echo-request by sending an echo-reply.  This option can be used with
+the \fIlcp-echo-failure\fR option to detect that the peer is no longer
+connected.
+.TP
+.B lcp-echo-failure \fI<n>
+If this option is given, \fIpppd\fR will presume the peer to be dead
+if \fIn\fR LCP echo-requests are sent without receiving a valid LCP
+echo-reply.  If this happens, \fIpppd\fR will terminate the
+connection.  Use of this option requires a non-zero value for the
+\fIlcp-echo-interval\fR parameter.  This option can be used to enable
+\fIpppd\fR to terminate after the physical connection has been broken
+(e.g., the modem has hung up) in situations where no hardware modem
+control lines are available.
+.TP
+.B lcp-restart \fI<n>
+Set the LCP restart interval (retransmission timeout) to <n> seconds
+(default 3).
+.TP
+.B lcp-max-terminate \fI<n>
+Set the maximum number of LCP terminate-request transmissions to <n>
+(default 3).
+.TP
+.B lcp-max-configure \fI<n>
+Set the maximum number of LCP configure-request transmissions to <n>
+(default 10).
+.TP
+.B lcp-max-failure \fI<n>
+Set the maximum number of LCP configure-NAKs returned before starting
+to send configure-Rejects instead to <n> (default 10).
+.TP
+.B ipcp-restart \fI<n>
+Set the IPCP restart interval (retransmission timeout) to <n> seconds
+(default 3).
+.TP
+.B ipcp-max-terminate \fI<n>
+Set the maximum number of IPCP terminate-request transmissions to <n>
+(default 3).
+.TP
+.B ipcp-max-configure \fI<n>
+Set the maximum number of IPCP configure-request transmissions to <n>
+(default 10).
+.TP
+.B ipcp-max-failure \fI<n>
+Set the maximum number of IPCP configure-NAKs returned before starting
+to send configure-Rejects instead to <n> (default 10).
+.TP
+.B pap-restart \fI<n>
+Set the PAP restart interval (retransmission timeout) to <n> seconds
+(default 3).
+.TP
+.B pap-max-authreq \fI<n>
+Set the maximum number of PAP authenticate-request transmissions to
+<n> (default 10).
+.TP
+.B chap-restart \fI<n>
+Set the CHAP restart interval (retransmission timeout for challenges)
+to <n> seconds (default 3).
+.TP
+.B chap-max-challenge \fI<n>
+Set the maximum number of CHAP challenge transmissions to <n> (default
+10).
+.TP
+.B chap-interval \fI<n>
+If this option is given,
+.I pppd
+will rechallenge the peer every <n> seconds.
+.TP
+.B ipcp-accept-local
+With this option,
+.I pppd
+will accept the peer's idea of our local IP address, even if the
+local IP address was specified in an option.
+.TP
+.B ipcp-accept-remote
+With this option,
+.I pppd
+will accept the peer's idea of its (remote) IP address, even if the
+remote IP address was specified in an option.
+.SH OPTIONS FILES
+Options can be taken from files as well as the command line.  
+.I pppd
+reads options from the files /etc/ppp/options and ~/.ppprc before
+looking at the command line.  An options file is parsed into a series
+of words, delimited by whitespace.  Whitespace can be included in a
+word by enclosing the word in quotes (").  A backslash (\\) quotes the
+following character.  A hash (#) starts a comment, which continues
+until the end of the line.
+.SH AUTHENTICATION
+.I pppd
+provides system administrators with sufficient access control that PPP
+access to a server machine can be provided to legitimate users without
+fear of compromising the security of the server or the network it's
+on.  In part this is provided by the /etc/ppp/options file, where the
+administrator can place options to require authentication whenever
+.I pppd
+is run, and in part by the PAP and CHAP secrets files, where the
+administrator can restrict the set of IP addresses which individual
+users may use.
+.LP
+The default behaviour of
+.I pppd
+is to agree to authenticate if requested, and to not
+require authentication from the peer.  However, 
+.I pppd
+will not agree to
+authenticate itself with a particular protocol if it has no secrets
+which could be used to do so.
+.LP
+Authentication is based on secrets, which are selected from secrets
+files (/etc/ppp/pap-secrets for PAP, /etc/ppp/chap-secrets for CHAP).
+Both secrets files have the same format, and both can store secrets
+for several combinations of server (authenticating peer) and client
+(peer being authenticated).  Note that
+.I pppd
+can be both a server
+and client, and that different protocols can be used in the two
+directions if desired.
+.LP
+A secrets file is parsed into words as for a options file.  A secret
+is specified by a line containing at least 3 words, in the order
+client, server, secret.  Any following words on the same line are
+taken to be a list of acceptable IP addresses for that client.  If
+there are only 3 words on the line, it is assumed that any IP address
+is OK; to disallow all IP addresses, use "-".  If the secret starts
+with an `@', what follows is assumed to be the name of a file from
+which to read the secret.  A "*" as the client or server name matches
+any name.  When selecting a secret, \fIpppd\fR takes the best match, i.e.
+the match with the fewest wildcards.
+.LP
+Thus a secrets file contains both secrets for use in authenticating
+other hosts, plus secrets which we use for authenticating ourselves to
+others.  Which secret to use is chosen based on the names of the host
+(the `local name') and its peer (the `remote name').  The local name
+is set as follows:
+.TP 3
+if the \fBusehostname\fR option is given,
+then the local name is the hostname of this machine
+(with the domain appended, if given)
+.TP 3
+else if the \fBname\fR option is given,
+then use the argument of the first \fBname\fR option seen
+.TP 3
+else if the local IP address is specified with a hostname,
+then use that name
+.TP 3
+else use the hostname of this machine (with the domain appended, if given)
+.LP
+When authenticating ourselves using PAP, there is also a `username'
+which is the local name by default, but can be set with the \fBuser\fR
+option or the \fB+ua\fR option.
+.LP
+The remote name is set as follows:
+.TP 3
+if the \fBremotename\fR option is given,
+then use the argument of the last \fBremotename\fR option seen
+.TP 3
+else if the remote IP address is specified with a hostname,
+then use that host name
+.TP 3
+else the remote name is the null string "".
+.LP
+Secrets are selected from the PAP secrets file as follows:
+.TP 2
+*
+For authenticating the peer, look for a secret with client ==
+username specified in the PAP authenticate-request, and server ==
+local name.
+.TP 2
+*
+For authenticating ourselves to the peer, look for a secret with
+client == our username, server == remote name.
+.LP
+When authenticating the peer with PAP, a secret of "" matches any
+password supplied by the peer.  If the password doesn't match the
+secret, the password is encrypted using crypt() and checked against
+the secret again; thus secrets for authenticating the peer can be
+stored in encrypted form.  If the \fBlogin\fR option was specified, the
+username and password are also checked against the system password
+database.  Thus, the system administrator can set up the pap-secrets
+file to allow PPP access only to certain users, and to restrict the
+set of IP addresses that each user can use.
+.LP
+Secrets are selected from the CHAP secrets file as follows:
+.TP 2
+*
+For authenticating the peer, look for a secret with client == name
+specified in the CHAP-Response message, and server == local name.
+.TP 2
+*
+For authenticating ourselves to the peer, look for a secret with
+client == local name, and server == name specified in the
+CHAP-Challenge message.
+.LP
+Authentication must be satisfactorily completed before IPCP (or any
+other Network Control Protocol) can be started.  If authentication
+fails, \fIpppd\fR will terminated the link (by closing LCP).  If IPCP
+negotiates an unacceptable IP address for the remote host, IPCP will
+be closed.  IP packets can only be sent or received when IPCP is open.
+.LP
+In some cases it is desirable to allow some hosts which can't
+authenticate themselves to connect and use one of a restricted set of
+IP addresses, even when the local host generally requires
+authentication.  If the peer refuses to authenticate itself when
+requested, \fIpppd\fR takes that as equivalent to authenticating with
+PAP using the empty string for the username and password.  Thus, by
+adding a line to the pap-secrets file which specifies the empty string
+for the client and password, it is possible to allow restricted access
+to hosts which refuse to authenticate themselves.
+.SH ROUTING
+.LP
+When IPCP negotiation is completed successfully,
+.I pppd
+will inform the kernel of the local and remote IP addresses for the
+ppp interface.  This is sufficient to create a
+host route to the remote end of the link, which will enable the peers
+to exchange IP packets.  Communication with other machines generally
+requires further modification to routing tables and/or ARP (Address
+Resolution Protocol) tables.  In some cases this will be done
+automatically through the actions of the \fIrouted\fR or \fIgated\fR
+daemons, but in most cases some further intervention is required.
+.LP
+Sometimes it is desirable
+to add a default route through the remote host, as in the case of a
+machine whose only connection to the Internet is through the ppp
+interface.  The \fBdefaultroute\fR option causes \fIpppd\fR to create such a
+default route when IPCP comes up, and delete it when the link is
+terminated.
+.LP
+In some cases it is desirable to use proxy ARP, for example on a
+server machine connected to a LAN, in order to allow other hosts to
+communicate with the remote host.  The \fBproxyarp\fR option causes \fIpppd\fR
+to look for a network interface on the same subnet as the remote host
+(an interface supporting broadcast and ARP, which is up and not a
+point-to-point or loopback interface).  If found, \fIpppd\fR creates a
+permanent, published ARP entry with the IP address of the remote host
+and the hardware address of the network interface found.
+.SH EXAMPLES
+.LP
+In the simplest case, you can connect the serial ports of two machines
+and issue a command like
+.IP
+pppd /dev/ttya 9600 passive
+.LP
+to each machine, assuming there is no \fIgetty\fR running on the
+serial ports.  If one machine has a \fIgetty\fR running, you can use
+\fIkermit\fR or \fItip\fR on the other machine to log in to the first
+machine and issue a command like
+.IP
+pppd passive
+.LP
+Then exit from the communications program (making sure the connection
+isn't dropped), and issue a command like
+.IP
+pppd /dev/ttya 9600
+.LP
+The process of logging in to the other machine and starting \fIpppd\fR
+can be automated by using the \fBconnect\fR option to run \fIchat\fR,
+for example:
+.IP
+pppd /dev/ttya 38400 connect 'chat "" "" "login:" "username"
+"Password:" "password" "% " "exec pppd passive"'
+.LP
+(Note however that running chat like this will leave the password
+visible in the parameter list of pppd and chat.)
+.LP
+If your serial connection is any more complicated than a piece of
+wire, you may need to arrange for some control characters to be
+escaped.  In particular, it is often useful to escape XON (^Q) and
+XOFF (^S), using \fBasyncmap a0000\fR.  If the path includes a telnet,
+you probably should escape ^] as well (\fBasyncmap 200a0000\fR).
+If the path includes an rlogin, you will need to use the \fBescape
+ff\fR option on the end which is running the rlogin client, since many
+rlogin implementations are not
+transparent; they will remove the sequence [0xff, 0xff, 0x73, 0x73,
+followed by any 8 bytes] from the stream.
+.SH DIAGNOSTICS
+.LP
+Messages are sent to the syslog daemon using facility LOG_DAEMON.
+(This can be overriden by recompiling \fIpppd\fR with the macro
+LOG_PPP defined as the desired facility.)  In order to see the error
+and debug messages, you will need to edit your /etc/syslog.conf file
+to direct the messages to the desired output device or file.
+.LP
+The \fBdebug\fR option causes the contents of all control packets sent
+or received to be logged, that is, all LCP, PAP, CHAP or IPCP packets.
+This can be useful if the PPP negotiation does not succeed.
+If debugging is enabled at compile time, \fIpppd\fR uses facility
+LOG_LOCAL2 instead of LOG_DAEMON, and the \fBdebug\fR option
+causes additional debugging messages to be logged.
+.LP
+Debugging can also be enabled by sending a
+SIGUSR1 to the
+.I pppd
+process.
+Debugging may be disabled by sending a SIGUSR2 to the
+.I pppd
+process.
+.SH FILES
+.TP
+.B /var/run/ppp\fIn\fB.pid \fR(BSD), \fB/etc/ppp/ppp\fIn\fB.pid \fR(SunOS)
+Process-ID for \fIpppd\fR process on ppp interface unit \fIn\fR.
+.TP
+.B /etc/ppp/ip-up
+A program or script which is executed when the link is available for
+sending and receiving IP packets (that is, IPCP has come up).  It is
+executed with the parameters \fIinterface-name tty-device speed
+local-IP-address remote-IP-address\fR.
+.IP
+This program or script is executed with the same real and effective
+user-ID as \fIpppd\fR, that is, at least the effective user-ID and
+possibly the real user-ID will be \fBroot\fR.  This is so that it can
+be used to manipulate routes, run privileged daemons (e.g.
+\fBsendmail\fR), etc.  Be careful that the contents of the
+/etc/ppp/ip-up and /etc/ppp/ip-down scripts do not compromise your
+system's security.
+.TP
+.B /etc/ppp/ip-down
+A program or script which is executed when the link is no longer
+available for sending and receiving IP packets.  This script can be
+used for undoing the effects of the /etc/ppp/ip-up script.  It is
+invoked with the same parameters as the ip-up script, and the same
+security considerations apply, since it is executed with the same
+effective and real user-IDs as \fIpppd\fR.
+.TP
+.B /etc/ppp/pap-secrets
+Usernames, passwords and IP addresses for PAP authentication.
+.TP
+.B /etc/ppp/chap-secrets
+Names, secrets and IP addresses for CHAP authentication.
+.TP
+.B /etc/ppp/options
+System default options for
+.I pppd,
+read before user default options or command-line options.
+.TP
+.B ~/.ppprc
+User default options, read before command-line options.
+.TP
+.B /etc/ppp/options.\fIttyname
+System default options for the serial port being used, read after
+command-line options.
+.SH SEE ALSO
+.TP
+.B RFC1144
+Jacobson, V.
+.I Compressing TCP/IP headers for low-speed serial links.
+1990 February.
+.TP
+.B RFC1321
+Rivest, R.
+.I The MD5 Message-Digest Algorithm.
+1992 April.
+.TP
+.B RFC1332
+McGregor, G.
+.I PPP Internet Protocol Control Protocol (IPCP).
+1992 May.
+.TP
+.B RFC1334
+Lloyd, B.; Simpson, W.A.
+.I PPP authentication protocols.
+1992 October.
+.TP
+.B RFC1548
+Simpson, W.A.
+.I The Point\-to\-Point Protocol (PPP).
+1993 December.
+.TP
+.B RFC1549
+Simpson, W.A.
+.I PPP in HDLC Framing.
+1993 December
+.SH NOTES
+The following signals have the specified effect when sent to the
+.I pppd
+process.
+.TP
+.B SIGINT, SIGTERM
+These signals cause \fIpppd\fR to terminate the link (by closing LCP),
+restore the serial device settings, and exit.
+.TP
+.B SIGHUP
+Indicates that the physical layer has been disconnected.  \fIpppd\fR
+will attempt to restore the serial device settings (this may produce
+error messages on Suns), and then exit.
+.SH BUGS
+The use of the modem control lines and the effects of the \fBmodem\fR
+and \fBlocal\fR options are not well defined.
+.SH AUTHORS
+Drew Perkins,
+Brad Clements,
+Karl Fox,
+Greg Christy,
+Brad Parker (brad@fcr.com),
+Paul Mackerras (paulus@cs.anu.edu.au)