ipppd
IPPPD(8) Linux System Administration IPPPD(8)
NAME
ipppd - (ISDN) Point to Point Protocol daemon
SYNOPSIS
/usr/sbin/ipppd [ options ] [ device ]
DESCRIPTION
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 Con-
trol Protocols (NCP) for establishing and configuring different net-
work-layer protocols.
The encapsulation scheme is provided by driver code in the kernel.
ipppd provides the basic LCP, authentication support, and an NCP for
establishing and configuring the Internet Protocol (IP) (called the IP
Control Protocol, IPCP).
NOTES for (ISDN) IPPPD
This special (ISDN) PPP daemon is a modified version of pppd and pro-
vides synchronous PPP for ISDN connections.
If you need asynchronous PPP over ISDN lines use pppd instead with the
ISDN character devices, see ttyI(4).
The ipppd can handle multiple devices. This is necessary to link sev-
eral connections together to one bundle. ipppd should be started
once. It opens the devices and waits for connections. If the connec-
tions is closed ipppd reopens the device automatically (the device,
that’s it ... not the link to the remote). So you shouldn’t kill the
ipppd to close a link. Instead, trigger a hangup on the netdevice
layer by ’isdnctrl hangup <device>’.
The facility to configure the daemon via file /etc/ppp/ioptions.<dev-
name> is disabled. The ’file’ option or the command line may be used
for individual configuration.
Do not set the permissions of the program to ’setuid to root on execu-
tion’. Call the daemon as root instead. No common user should have
the need to call the daemon!
OPTIONS
<device>
Communicate over the named device. The string "/dev/" is
prepended if necessary. If no device name is given, or if the
name of the controlling terminal is given, ipppd will use the
controlling terminal, and will not fork to put itself in the
background.
<local_IP_address>:<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 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, ipppd
will not accept a different value from the peer in the IPCP
negotiation, unless the ipcp-accept-local and/or ipcp-accept-
remote options are given, respectively.
active-filter filter-expression
Specifies a packet filter to be applied to data packets to
determine which packets are to be regarded as link activity,
and therefore reset the idle timer, or cause the link to be
brought up in demand-dialling mode. This option is useful in
conjunction with the idle option if there are packets being
sent or received regularly over the link (for example, routing
information packets) which would otherwise prevent the link
from ever appearing to be idle. The filter-expression syntax
is as described for tcpdump(1), except that qualifiers which
are inappropriate for a PPP link, such as ether and arp, are
not permitted. Generally the filter expression should be
enclosed in single-quotes to prevent whitespace in the expres-
sion from being interpreted by the shell. This option is cur-
rently only available if both the kernel and ipppd were com-
piled with IPPP_FILTER defined.
-ac Disable Address/Control compression negotiation (use default,
i.e. address/control field compression disabled).
-all Don’t request or allow negotiation of any options for LCP and
IPCP (use default values).
auth Require the peer to authenticate itself before allowing network
packets to be sent or received.
bsdcomp nr,nt
Request that the peer compress packets that it sends, using the
BSD-Compress scheme, with a maximum code size of nr bits, and
agree to compress packets sent to the peer with a maximum code
size of nt bits. If nt is not specified, it defaults to the
value given for nr. Values in the range 9 to 15 may be used
for nr and nt; larger values give better compression but con-
sume more kernel memory for compression dictionaries. Alterna-
tively, a value of 0 for nr or nt disables compression in the
corresponding direction.
-bsdcomp
Disables compression; ipppd will not request or agree to com-
press packets using the BSD-Compress scheme.
callback <string>
Request the peer to call back at the location given in
<string>. Ususally this is a phone number, but it may be inter-
preted differently (or ignored) depending on the callback-type
option. If <string> is the empty string, ipppd automatically
tries to negotiate a callback type that does not need a loca-
tion to be specified.
callback-delay <n>
Callback delay for CBCP in seconds. If callback is negotiated
using CBCP, request that the peer waits at least <n> seconds
before calling back. Ignored if callback is negotiated as spec-
ified in RFC 1570. Legal range is 0..255, default is 5.
callback-cbcp
Enable callback negotiation via CBCB (default).
-callback-cbcp
Disable callback negotiation via CBCB.
no-callback-cbcp
Disable callback negotiation via CBCB.
callback-cbcp-preferred
If both CBCP and RFC 1570 style callback negotiation is
enabled, CBCP is preferred (default)
callback-rfc1570-preferred
If both CBCP and RFC 1570 style callback negotiation is
enabled, RFC 1570 style is preferred.
callback-rfc1570
Enable RFC 1570 style callback negotiation (default).
-callback-rfc1570
Disable RFC 1570 style callback negotiation.
no-callback-rfc1570
Disable RFC 1570 style callback negotiation (default).
callback-type <n>
Specifies how to interpret the location identifier given as
parameter of the callback option. Legal values are 0..4. A
value of 0 means that only callback types should be negotiated
that need no extra location id. No location id is sent to the
peer in this case. For RFC 1570 style callback negotiation,
the values 1..4 indicate how the peer should interpret the
location identifier: 1 - id is a system specific dial string,
2 - id is used for database lookup by the peer, 3 - id is a
phone number, and 4 id is a name. For CBCP callback negotia-
tion, the location id is always interpreted as a phone number.
-ccp Necessary for a few netblazers on the remote side.
noccp same as -ccp
+chap Require the peer to authenticate itself using CHAP [Crypto-
graphic Handshake Authentication Protocol] authentication.
-chap Don’t agree to authenticate using CHAP.
chap-interval <n>
If this option is given, ipppd will rechallenge the peer every
<n> seconds.
chap-max-challenge <n>
Set the maximum number of CHAP challenge transmissions to <n>
(default 10).
chap-restart <n>
Set the CHAP restart interval (retransmission timeout for chal-
lenges) to <n> seconds (default 3).
debug Increase debugging level (same as -d). If this option is
given, ipppd will log the contents of all control packets sent
or received in a readable form. The packets are logged through
syslog with facility daemon and level debug. This information
can be directed to a file by setting up /etc/syslog.conf appro-
priately (see syslog.conf(5)).
-d Increase debugging level (same as the debug option).
defaultroute
Add a default route to the system routing tables, using the
peer as the gateway, when IPCP negotiation is successfully com-
pleted. This entry is removed when the PPP connection is bro-
ken.
-defaultroute
Disable the defaultroute option. The system administrator who
wishes to prevent users from creating default routes with ipppd
can do so by placing this option in the /etc/ppp/ioptions file.
deldefaultroute
Replace default route if it already exists. Together with the
option defaultroute, this will replace any existing default
route by a new one through this ipppd’s interface when it comes
up.
-detach
Don’t fork to become a background process (otherwise ipppd will
do so if a serial device other than its controlling terminal is
specified).
domain <d>
Append the domain name <d> to the local host name for authenti-
cation 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.
file <f>
Read options from file <f> (the format is described below).
-ip Disable IP address negotiation. If this option is used, the
remote IP address must be specified with an option on the com-
mand line or in an options file.
+ip-protocol
Enable the IPCP and IP protocols. This is the default condi-
tion. This option is only needed if the default setting is -ip-
protocol.
-ip-protocol
Disable the IPCP and IP protocols. This should only be used if
you know that you are using a client which only understands IPX
and you don’t want to confuse the client with the IPCP proto-
col.
+ipx-protocol
Enable the IPXCP and IPX protocols. This is the default condi-
tion if your kernel supports IPX. This option is only needed if
the default setting is -ipx-protocol. If your kernel does not
support IPX then this option will have no effect.
-ipx-protocol
Disable the IPXCP and IPX protocols. This should only be used
if you know that you are using a client which only understands
IP and you don’t want to confuse the client with the IPXCP pro-
tocol.
ipcp-accept-local
With this option, ipppd will accept the peer’s idea of our
local IP address, even if the local IP address was specified in
an option.
ipcp-accept-remote
With this option, ipppd will accept the peer’s idea of its
(remote) IP address, even if the remote IP address was speci-
fied in an option.
ipcp-max-configure <n>
Set the maximum number of IPCP configure-request transmissions
to <n> (default 10).
ipcp-max-failure <n>
Set the maximum number of IPCP configure-NAKs returned before
starting to send configure-Rejects instead to <n> (default 10).
ipcp-max-terminate <n>
Set the maximum number of IPCP terminate-request transmissions
to <n> (default 3).
ipcp-restart <n>
Set the IPCP restart interval (retransmission timeout) to <n>
seconds (default 3).
ipparam string
Provides an extra parameter to the ip-up and ip-down scripts.
If this option is given, the string supplied is given as the
6th parameter to those scripts.
ipx-network <n>
Set the IPX network number in the IPXCP configure request frame
to <n>. There is no valid default. If this option is not speci-
fied then the network number is obtained from the peer. If the
peer does not have the network number, the IPX protocol will
not be started. This is a hexadecimal number and is entered
without any leading sequence such as 0x. It is related to the
ipxcp-accept-network option.
ipx-node <n>:<m>
Set the IPX node numbers. The two node numbers are separated
from each other with a colon character. The first number <n> is
the local node number. The second number <m> is the peer’s node
number. Each node number is a hexadecimal number, to the maxi-
mum of ten significant digits. The node numbers on the ipx-net-
work must be unique. There is no valid default. If this option
is not specified then the node number is obtained from the
peer. This option is a related to the ipxcp-accept-local and
ipxcp-accept-remote options.
ipx-router-name <string>
Set the name of the router. This is a string and is sent to the
peer as information data.
ipx-routing <n>
Set the routing protocol to be received by this option. Use a
comma-serperated list if you want to specify more than one pro-
tocol. The ’none’ option (0) may be specified as the only
instance of ipx-routing. The values may be 0 for NONE, 2 for
RIP/SAP, and 4 for NLSP.
ipxcp-accept-local
Accept the peer’s NAK for the node number specified in the ipx-
node option. If a node number was specified, and non-zero, the
default is to insist that the value be used. If you include
this option then you will permit the peer to override the entry
of the node number.
ipxcp-accept-network
Accept the peer’s NAK for the network number specified in the
ipx-network option. If a network number was specified, and non-
zero, the default is to insist that the value be used. If you
include this option then you will permit the peer to override
the entry of the node number.
ipxcp-accept-remote
Use the peer’s network number specified in the configure
request frame. If a node number was specified for the peer and
this option was not specified, the peer will be forced to use
the value which you have specified.
ipxcp-max-configure <n>
Set the maximum number of IPXCP configure request frames which
the system will send to <n>. The default is 10.
ipxcp-max-failure <n>
Set the maximum number of IPXCP NAK frames which the local sys-
tem will send before it rejects the options. The default value
is 3.
ipxcp-max-terminate <n>
Set the maximum nuber of IPXCP terminate request frames before
the local system considers that the peer is not listening to
them. The default value is 3.
kdebug n
Enable debugging code in the kernel-level PPP driver. The
argument n is a number which is the sum of the following val-
ues: 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.
lcp-echo-failure <n>
If this option is given, ipppd will presume the peer to be dead
if n LCP echo-requests are sent without receiving a valid LCP
echo-reply. If this happens, ipppd will terminate the connec-
tion. Use of this option requires a non-zero value for the
lcp-echo-interval parameter. This option can be used to enable
ipppd to terminate after the physical connection has been bro-
ken (e.g., the line hung up) in situations where no hardware
modem control lines are available.
lcp-echo-interval <n>
If this option is given, ipppd will send an LCP echo-request
frame to the peer every n seconds. With Linux, the echo-
request is sent when no packets have been received from the
peer for n seconds. Normally the peer should respond to the
echo-request by sending an echo-reply. This option can be used
with the lcp-echo-failure option to detect that the peer is no
longer connected.
lcp-max-configure <n>
Set the maximum number of LCP configure-request transmissions
to <n> (default 10).
lcp-max-failure <n>
Set the maximum number of LCP configure-NAKs returned before
starting to send configure-Rejects instead to <n> (default 10).
lcp-max-terminate <n>
Set the maximum number of LCP terminate-request transmissions
to <n> (default 3).
lcp-restart <n>
Set the LCP restart interval (retransmission timeout) to <n>
seconds (default 3).
lock Specifies that ipppd should create a UUCP-style lock file for
the serial device to ensure exclusive access to the device.
login Use the system password database for authenticating the peer
using PAP, and record the user in the system wtmp file.
-mn Disable magic number negotiation. With this option, ipppd can-
not detect a looped-back line.
+mp enables MPPP negotiation
mru <n>
Set the MRU [Maximum Receive Unit] value to <n> for negotia-
tion. ipppd 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).
-mru Disable MRU [Maximum Receive Unit] negotiation. With this
option, ipppd will use the default MRU value of 1500 bytes.
ms-dns <n>
This option sets the IP address or addresses for the Domain
Name Server. It is used by Microsoft Windows clients. The pri-
mary DNS address is specified by the first instance of the ms-
dns option. The secondary is specified by the second instance.
ms-get-dns
Implements the client side of RFC1877. If ipppd is acting as a
client to a server that implements RFC1877 such as one intended
to be used with Microsoft Windows clients, this option allows
ipppd to obtain one or two DNS (Domain Name Server) addresses
from the server. It does not do anything with these addresses
except put them in the environment (MS_DNS1 MS_DNS2) that is
passed to scripts. For compatibility with the async pppd, DNS1
DNS2 environment variables are also set. A sample resolv.conf
is created in /etc/ppp/resolv.conf. The /etc/ppp/ip-up script
should use this information to perform whatever adjustment is
necessary. Note: RFC1877 is a horrible protocol layering vio-
lation, the correct approach would be to use DHCP after the
IPCP phase.
ms-get-wins
As ms-get-dns but for WINS (Windows Internet Name Services)
server addresses. Environment variables are MS_WINS1 and
MS_WINS2.
mtu <n>
Set the MTU [Maximum Transmit Unit] value to <n>. Unless the
peer requests a smaller value via MRU negotiation, ipppd will
request that the kernel networking code send data packets of no
more than n bytes through the PPP network interface.
name <n>
Set the name of the local system for authentication purposes to
<n>.
netmask <n>
Set the interface netmask to <n>, a 32 bit netmask in "decimal
dot" notation (e.g. 255.255.255.0). If this option is given,
the value specified is ORed with the default netmask. The
default netmask is chosen based on the negotiated remote IP
address; it is the appropriate network mask for the class of
the remote IP address, ORed with the netmasks for any non
point-to-point network interfaces in the system which are on
the same network.
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).
passive
Enables the "passive" option in the LCP. With this option,
ipppd will attempt to initiate a connection; if no reply is
received from the peer, ipppd will then just wait passively for
a valid LCP packet from the peer (instead of exiting, as it
does without this option).
-p Same as the passive option.
+pap Require the peer to authenticate itself using PAP.
-pap Don’t agree to authenticate using PAP.
papcrypt
Indicates that all secrets in the /etc/ppp/pap-secrets file
which are used for checking the identity of the peer are
encrypted, and thus ipppd should not accept a password which
(before encryption) is identical to the secret from the
/etc/ppp/pap-secrets file.
pap-max-authreq <n>
Set the maximum number of PAP authenticate-request transmis-
sions to <n> (default 10).
pap-restart <n>
Set the PAP restart interval (retransmission timeout) to <n>
seconds (default 3).
pap-timeout <n>
Set the maximum time that ipppd will wait for the peer to
authenticate itself with PAP to <n> seconds (0 means no limit).
pass-filter filter-expression
Specifies a packet filter to applied to data packets being sent
or received to determine which packets should be allowed to
pass. Packets which are rejected by the filter are silently
discarded. This option can be used to prevent specific network
daemons (such as routed) using up link bandwidth, or to provide
a basic firewall capability. The filter-expression syntax is
as described for tcpdump(1), except that qualifiers which are
inappropriate for a PPP link, such as ether and arp, are not
permitted. Generally the filter expression should be enclosed
in single-quotes to prevent whitespace in the expression from
being interpreted by the shell. Note that it is possible to
apply different constraints to incoming and outgoing packets
using the inbound and outbound qualifiers. This option is cur-
rently only available if both the kernel and ipppd were com-
piled with IPPP_FILTER defined.
-pc Disable protocol field compression negotiation (use default,
i.e. protocol field compression disabled).
pidfile <filename>
Use <filename> instead of /var/run/ipppd.pid
pred1comp
Attempt to request that the peer send the local system frames
which have been compressed by the Predictor-1 compression. The
compression protocols must be loaded or this option will be
ignored.
-pred1comp
Do not accept Predictor-1 comprssion, even if the peer wants to
send this type of compression and support has been defined in
the kernel.
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.
-proxyarp
Disable the proxyarp option. The system administrator who
wishes to prevent users from creating proxy ARP entries with
ipppd can do so by placing this option in the /etc/ppp/ioptions
file.
remotename <n>
Set the assumed name of the remote system for authentication
purposes to <n>.
set_userip
You may define valid IPs in /etc/ppp/useriptab
silent With this option, ipppd will not transmit LCP packets to initi-
ate a connection until a valid LCP packet is received from the
peer (as for the ‘passive’ option with ancient versions of
ipppd).
+ua <p>
Agree to authenticate using PAP [Password Authentication Proto-
col] 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 obso-
lescent.
usefirstip
Gets the remote address from the first entry in the auth file
(if there is an IP address entry). This address should be a
full IP address not an address from a masked area. Ipppd calls
’gethostbyname()’ and negotiates the result. IP from auth file
will overwrite the remote address gotten from the interface.
’usefirstip’ is UNTESTED!
usehostname
Enforce the use of the hostname as the name of the local system
for authentication purposes (overrides the name option).
usepeerdns
Same as ms-get-dns for compatibility with async pppd.
user <u>
Set the user name to use for authenticating this machine with
the peer using PAP to <u>.
useifip
will get (if not set to 0.0.0.0) the IP address for the negoti-
ation from the attached network-interface. (also: ipppd will
try to negotiate ’pointopoint’ IP as remote IP) interface
address -> local IP pointopoint address -> remote IP
-vj Disable negotiation of Van Jacobson style TCP/IP header com-
pression (use default, i.e. no compression).
-vjccomp
Disable the connection-ID compression option in Van Jacobson
style TCP/IP header compression. With this option, ipppd will
not omit the connection-ID byte from Van Jacobson compressed
TCP/IP headers, nor ask the peer to do so.
vj-max-slots n
Sets the number of connection slots to be used by the Van
Jacobson TCP/IP header compression and decompression code to n,
which must be between 2 and 16 (inclusive).
OPTIONS FILES
Options can be taken from files as well as the command line. ipppd
reads options from the file /etc/ppp/ioptions 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 follow-
ing character. A hash (#) starts a comment, which continues until the
end of the line.
AUTHENTICATION
ipppd 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/ioptions
file, where the administrator can place options to require authentica-
tion whenever ipppd 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.
The default behaviour of ipppd is to agree to authenticate if
requested, and to not require authentication from the peer. However,
ipppd will not agree to authenticate itself with a particular protocol
if it has no secrets which could be used to do so.
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 ipppd can be both a server and
client, and that different protocols can be used in the two directions
if desired.
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 name, server name, 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, ipppd takes the best
match, i.e. the match with the fewest wildcards.
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:
if the usehostname option is given,
then the local name is the hostname of this machine (with the
domain appended, if given)
else if the name option is given,
then use the argument of the first name option seen
else if the local IP address is specified with a hostname,
then use that name
else use the hostname of this machine (with the domain appended, if
given)
When authenticating ourselves using PAP, there is also a ‘username’
which is the local name by default, but can be set with the user
option or the +ua option.
The remote name is set as follows:
if the remotename option is given,
then use the argument of the last remotename option seen
else if the remote IP address is specified with a hostname,
then use that host name
else the remote name is the null string "".
Secrets are selected from the PAP secrets file as follows:
* For authenticating the peer, look for a secret with client == user-
name specified in the PAP authenticate-request, and server == local
name.
* For authenticating ourselves to the peer, look for a secret with
client == our username, server == remote name.
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 papcrypt option is given, the first
(unencrypted) comparison is omitted, for better security.
If the login option was specified, the username and password are also
checked against the system password database. Thus, the system admin-
istrator 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. Typically, when using the login option, the secret in
/etc/ppp/pap-secrets would be "", to avoid the need to have the same
secret in two places.
Secrets are selected from the CHAP secrets file as follows:
* For authenticating the peer, look for a secret with client == name
specified in the CHAP-Response message, and server == local name.
* For authenticating ourselves to the peer, look for a secret with
client == local name, and server == name specified in the CHAP-Chal-
lenge message.
Authentication must be satisfactorily completed before IPCP (or any
other Network Control Protocol) can be started. If authentication
fails, ipppd will terminated the link (by closing LCP). If IPCP nego-
tiates an unacceptable IP address for the remote host, IPCP will be
closed. IP packets can only be sent or received when IPCP is open.
In some cases it is desirable to allow some hosts which can’t authen-
ticate 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, ipppd 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 pass-
word, it is possible to allow restricted access to hosts which refuse
to authenticate themselves.
ROUTING
When IPCP negotiation is completed successfully, ipppd 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. Communica-
tion 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
routed or gated daemons, but in most cases some further intervention
is required.
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 Inter-
net is through the ppp interface. The defaultroute option causes
ipppd to create such a default route when IPCP comes up, and delete it
when the link is terminated.
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 proxyarp option causes ipppd 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, ipppd creates a permanent,
published ARP entry with the IP address of the remote host and the
hardware address of the network interface found.
DIAGNOSTICS
Messages are sent to the syslog daemon using facility LOG_DAEMON.
(This can be overriden by recompiling ipppd 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.
The debug 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 debug-
ging is enabled at compile time, the debug option also causes other
debugging messages to be logged.
Debugging can also be enabled or disabled by sending a SIGUSR1 to the
ipppd process. This signal acts as a toggle.
FILES
/var/run/ipppd.pid
Process-ID for ipppd process on ppp interface unit n.
/etc/ppp/ip-up
A program or script which is executed when the link is avail-
able for sending and receiving IP packets (that is, IPCP has
come up). It is executed with the parameters
interface-name tty-device speed local-IP-address remote-IP-
address
and with its standard input, output and error streams redi-
rected to /dev/null.
This program or script is executed with the same real and
effective user-ID as ipppd, that is, at least the effective
user-ID and possibly the real user-ID will be root. This is so
that it can be used to manipulate routes, run privileged dae-
mons (e.g. sendmail), etc. Be careful that the contents of
the /etc/ppp/ip-up and /etc/ppp/ip-down scripts do not compro-
mise your system’s security.
/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 ipppd.
/etc/ppp/ipx-up
A program or script which is executed when the link is avail-
able for sending and receiving IPX packets (that is, IPXCP has
come up). It is executed with the parameters
interface-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 ipppd-pid
and with its standard input, output and error streams redi-
rected to /dev/null.
The local-IPX-routing-protocol and remote-IPX-routing-protocol
field may be one of the following:
NONE to indicate that there is no routing protocol
RIP to indicate that RIP/SAP should be used
NLSP to indicate that Novell NLSP should be used
RIP NLSP to indicate that both RIP/SAP and NLSP should be used
This program or script is executed with the same real and
effective user-ID as ipppd, that is, at least the effective
user-ID and possibly the real user-ID will be root. This is so
that it can be used to manipulate routes, run privileged dae-
mons (e.g. ripd), etc. Be careful that the contents of the
/etc/ppp/ipx-up and /etc/ppp/ipx-down scripts do not compromise
your system’s security.
/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 with the same parameters as the ipx-
up script, and the same security considerations apply, since it
is executed with the same effective and real user-IDs as ipppd.
/etc/ppp/auth-up
This program or script is executed after successful authentica-
tion with the following parameters: interface name, authentica-
tion user name, username of ipppd, devicename, speed, remote
number
/etc/ppp/auth-down
This program or script is executed after a disconnection with
the following parameters: interface name, authentication user
name, username of ipppd, devicename, speed, remote number
/etc/ppp/auth-fail
This program or script is executed after a authentication fail-
ure with the following parameters: interface name, authentica-
tion user name, username of ipppd, devicename, speed, remote
number, failure reason
Valid reasons are:
1 = Timeout during pap auth
2 = pap protocol rejected
3 = pap secrets invalid
9 = Timeout during chap auth
10 = chap protocol rejected
11 = chap secrets invalid
/etc/ppp/pap-secrets
Usernames, passwords and IP addresses for PAP authentication.
/etc/ppp/chap-secrets
Names, secrets and IP addresses for CHAP authentication.
/etc/ppp/ioptions
System default options for ipppd, read before user default
options or command-line options.
SEE ALSO
ttyI(4), isdnctrl(8), ipppstats(8),
RFC1144
Jacobson, V. Compressing TCP/IP headers for low-speed serial
links. 1990 February.
RFC1321
Rivest, R. The MD5 Message-Digest Algorithm. 1992 April.
RFC1332
McGregor, G. PPP Internet Protocol Control Protocol (IPCP).
1992 May.
RFC1334
Lloyd, B.; Simpson, W.A. PPP authentication protocols. 1992
October.
RFC1548
Simpson, W.A. The Point-to-Point Protocol (PPP). 1993 Decem-
ber.
RFC1549
Simpson, W.A. PPP in HDLC Framing. 1993 December
NOTES
The following signals have the specified effect when sent to the ipppd
process.
SIGINT, SIGTERM
These signals cause ipppd to terminate the link (by closing
LCP), restore the serial device settings, and exit.
SIGHUP This signal causes ipppd to terminate the link, restore the
serial device settings, and close the serial device. If the
persist option has been specified, ipppd will try to reopen the
serial device and start another connection. Otherwise ipppd
will exit.
SIGUSR2
This signal causes ipppd to renegotiate compression. This can
be useful to re-enable compression after it has been disabled
as a result of a fatal decompression error. With the BSD Com-
press scheme, fatal decompression errors generally indicate a
bug in one or other implementation.
AUTHORS
Originally written by Drew Perkins, Brad Clements, Karl Fox, Greg
Christy, Brad Parker, Paul Mackerras <paulus@cs.anu.edu.au> for
(original) pppd.
Changes for ipppd by Klaus Franken <kfr@suse.de> and Michael Hipp
<Michael.Hipp@student.uni-tuebingen.de>.
Removal of pppd specific options and polish by Frank Elsner
<Elsner@zrz.TU-Berlin.DE>.
isdn4k-utils-3.3 2003/07/01 IPPPD(8)
