+Messages are sent to the syslog daemon using facility LOG_DAEMON.
+(This can be overriden by recompiling pppd 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 \fIdebug\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 or if
+authentication fails.
+If debugging is enabled at compile time, the \fIdebug\fR option also
+causes other debugging messages to be logged.
+.LP
+Debugging can also be enabled or disabled by sending a SIGUSR1 signal
+to the pppd process. This signal acts as a toggle.
+.SH EXIT STATUS
+The exit status of pppd is set to indicate whether any error was
+detected, or the reason for the link being terminated. The values
+used are:
+.TP
+.B 0
+Pppd has detached, or otherwise the connection was successfully
+established and terminated at the peer's request.
+.TP
+.B 1
+An immediately fatal error of some kind occurred, such as an essential
+system call failing, or running out of virtual memory.
+.TP
+.B 2
+An error was detected in processing the options given, such as two
+mutually exclusive options being used.
+.TP
+.B 3
+Pppd is not setuid-root and the invoking user is not root.
+.TP
+.B 4
+The kernel does not support PPP, for example, the PPP kernel driver is
+not included or cannot be loaded.
+.TP
+.B 5
+Pppd terminated because it was sent a SIGINT, SIGTERM or SIGHUP
+signal.
+.TP
+.B 6
+The serial port could not be locked.
+.TP
+.B 7
+The serial port could not be opened.
+.TP
+.B 8
+The connect script failed (returned a non-zero exit status).
+.TP
+.B 9
+The command specified as the argument to the \fIpty\fR option could
+not be run.
+.TP
+.B 10
+The PPP negotiation failed, that is, it didn't reach the point where
+at least one network protocol (e.g. IP) was running.
+.TP
+.B 11
+The peer system failed (or refused) to authenticate itself.
+.TP
+.B 12
+The link was established successfully and terminated because it was
+idle.
+.TP
+.B 13
+The link was established successfully and terminated because the
+connect time limit was reached.
+.TP
+.B 14
+Callback was negotiated and an incoming call should arrive shortly.
+.TP
+.B 15
+The link was terminated because the peer is not responding to echo
+requests.
+.TP
+.B 16
+The link was terminated by the modem hanging up.
+.TP
+.B 17
+The PPP negotiation failed because serial loopback was detected.
+.TP
+.B 18
+The init script failed (returned a non-zero exit status).
+.TP
+.B 19
+We failed to authenticate ourselves to the peer.
+.SH SCRIPTS
+Pppd invokes scripts at various stages in its processing which can be
+used to perform site-specific ancillary processing. These scripts are
+usually shell scripts, but could be executable code files instead.
+Pppd does not wait for the scripts to finish. The scripts are
+executed as root (with the real and effective user-id set to 0), so
+that they can do things such as update routing tables or run
+privileged daemons. Be careful that the contents of these scripts do
+not compromise your system's security. Pppd runs the scripts with
+standard input, output and error redirected to /dev/null, and with an
+environment that is empty except for some environment variables that
+give information about the link. The environment variables that pppd
+sets are:
+.TP
+.B DEVICE
+The name of the serial tty device being used.
+.TP
+.B IFNAME
+The name of the network interface being used.
+.TP
+.B IPLOCAL
+The IP address for the local end of the link. This is only set when
+IPCP has come up.
+.TP
+.B IPREMOTE
+The IP address for the remote end of the link. This is only set when
+IPCP has come up.
+.TP
+.B PEERNAME
+The authenticated name of the peer. This is only set if the peer
+authenticates itself.
+.TP
+.B SPEED
+The baud rate of the tty device.
+.TP
+.B ORIG_UID
+The real user-id of the user who invoked pppd.
+.TP
+.B PPPLOGNAME
+The username of the real user-id that invoked pppd. This is always set.
+.P
+For the ip-down and auth-down scripts, pppd also sets the following
+variables giving statistics for the connection:
+.TP
+.B CONNECT_TIME
+The number of seconds from when the PPP negotiation started until the
+connection was terminated.
+.TP
+.B BYTES_SENT
+The number of bytes sent (at the level of the serial port) during the
+connection.
+.TP
+.B BYTES_RCVD
+The number of bytes received (at the level of the serial port) during
+the connection.
+.TP
+.B LINKNAME
+The logical name of the link, set with the \fIlinkname\fR option.
+.P
+Pppd invokes the following scripts, if they exist. It is not an error
+if they don't exist.
+.TP
+.B /etc/ppp/auth-up
+A program or script which is executed after the remote system
+successfully authenticates itself. It is executed with the parameters
+.IP
+\fIinterface-name peer-name user-name tty-device speed\fR
+.IP
+Note that this script is not executed if the peer doesn't authenticate
+itself, for example when the \fInoauth\fR option is used.
+.TP
+.B /etc/ppp/auth-down
+A program or script which is executed when the link goes down, if
+/etc/ppp/auth-up was previously executed. It is executed in the same
+manner with the same parameters as /etc/ppp/auth-up.
+.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
+.IP
+\fIinterface-name tty-device speed local-IP-address
+remote-IP-address ipparam\fR
+.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 in the same manner and with the same parameters as the ip-up
+script.
+.TP
+.B /etc/ppp/ipv6-up
+Like /etc/ppp/ip-up, except that it is executed when the link is available
+for sending and receiving IPv6 packets. It is executed with the parameters
+.IP
+\fIinterface-name tty-device speed local-link-local-address
+remote-link-local-address ipparam\fR
+.TP
+.B /etc/ppp/ipv6-down
+Similar to /etc/ppp/ip-down, but it is executed when IPv6 packets can no
+longer be transmitted on the link. It is executed with the same parameters
+as the ipv6-up script.
+.TP
+.B /etc/ppp/ipx-up
+A program or script which is executed when the link is available for
+sending and receiving IPX packets (that is, IPXCP has come up). It is
+executed with the parameters
+.IP
+\fIinterface-name tty-device speed network-number local-IPX-node-address
+remote-IPX-node-address local-IPX-routing-protocol remote-IPX-routing-protocol
+local-IPX-router-name remote-IPX-router-name ipparam pppd-pid\fR
+.IP
+The local-IPX-routing-protocol and remote-IPX-routing-protocol field
+may be one of the following:
+.IP
+NONE to indicate that there is no routing protocol
+.br
+RIP to indicate that RIP/SAP should be used
+.br
+NLSP to indicate that Novell NLSP should be used
+.br
+RIP NLSP to indicate that both RIP/SAP and NLSP should be used
+.TP
+.B /etc/ppp/ipx-down
+A program or script which is executed when the link is no longer
+available for sending and receiving IPX packets. This script can be
+used for undoing the effects of the /etc/ppp/ipx-up script. It is
+invoked in the same manner and with the same parameters as the ipx-up
+script.