PPPD：
http://blog.csdn.net/skdkjzz/article/details/22209875
1、我的平台：SIMCOM 5360E 中国联通3G
首先是WCDMA脚本：
root@njqy:/etc/ppp/peers# cat kj_wcdma
#/etc/ppp/peers/wcdma
#This is pppd script, used SIMCOM 5360(Union)
/dev/ttyUSB3
115200
crtscts
modem
debug
nodetach
usepeerdns
defaultroute
user "3gnet"
connect '/usr/sbin/chat -s -v -f /etc/ppp/peers/wcdma-connect-chat'
root@njqy:/etc/ppp/peers#
wcdma-connect-chat脚本：
root@njqy:/etc/ppp/peers# cat wcdma-connect-chat
#/etc/ppp/wcdma-connect-chat
TIMEOUT 5
ABORT "DELAYED"
ABORT "BUSY"
ABORT "ERROR"
ABORT "NO DIALTONE"
ABORT "NO CARRIER" #异常处理
#"AT
#'OK-+++\c-OK' ATH0
'' AT
OK AT+CFUN=1 #实现基本的全功能模式
OK AT+CNAOP=2 #设置为WCDMA
OK AT+CNMP=14 #设置WCDMA模式
OK AT+CGDCONT=1,"IP","3gnet",,0,0 #VPN服务器
OK ATDT*99# #联通3G特殊号码
CONNECT ''
root@njqy:/etc/ppp/peers#
2、PPPD在man中详解：
NAME
pppd - 点对点协议守护进程
总览 SYNOPSIS
pppd [tty_name ] [ speed ] [ options ]
描述
点对点协议 (PPP) 提供一种在点对点串列线路上传输资料流 (datagrams)的方法。PPP是由三个部份所组成的：一个在串列线路上封装(encapsulating)资料流的方法，一个可延伸的连结控制协定(LinkControlProtocol:LCP)，以及一些用来建立并配置不同网路层协定的网路控制协定(NetworkControlProtocols:NCP)
封装的机制(scheme)是由核心中的驱动程式码来提供。pppd提供基本的LCP，验证(authentication)的支援，以及一个用来建立并配置网际网路协定(InternatProtocol(IP))（叫做IP控制协定，IPCP）的NCP。
常用选项 FREQUENTLY USED OPTIONS
- <tty_name>
在该名称的设备上进行通讯。如果需要的话可以前置一个 "/dev/"字串。如果没有给设备名称，pppd将会使用控制台的终端机(controllingteriminal)，并且产生(fork)出来时将不会把自己放到背景去。- <speed>
将波特率设为speed。在像是4.4BSD以及NetBSA的系统上，可以指定任何速率。其他系统(e.g.SunOs)只允许有限的几种速率。- asyncmap<map>
把非同步(async)字元设为对照到。这个对照表描述哪些控制字元不能在串列线路上成功地接收。pppd将会要求彼端以两个位元组的逸出序列(escapesequence)来传送这些字元。其参数是32位元的十六进位数字而每个位元代表一个得避开(escape)的字元。位元0(00000001) 代表字元0x00；位元31(80000000)代表字元0x1f或是^_。如果给了多个asyncmap选项，这些数值会以逻辑的或(OR)合在一起。如果没有给asyncmap选项，将没有非同步字元对照表会被加以协商来导引接收。这样彼端将会避开所有的控制字元。- auth
- 要求彼端在允许传送或接收网路封包之前先验证它自己。 This option is the default if the system has a default route. If neither this option nor thenoauth option is specified, pppd will only allow the peer to use IP addresses to which the system does not already have a route.
- callname
- Read options from the file /etc/ppp/peers/name. This file may contain privileged options, such asnoauth, even if pppd is not being run by root. The name string may not begin with / or include .. as a pathname component. The format of the options file is described below.
- connectscript
使用以所指定的可执行指令或是shell指令来设定串列线路。这个指令稿一般会使用"chat"程式来拨数据机并开始远端ppp区段作业(session)。 A value for this option from a privileged source cannot be overridden by a non-privileged user.- crtscts
- 使用硬体流量控制(i.e.RTS/CTS)来控制串列埠上的资料流。 If neither thecrtscts, thenocrtscts, the cdtrcts nor the nocdtrcts option is given, the hardware flow control setting for the serial port is left unchanged. Some serial ports (such as Macintosh serial ports) lack a true RTS output. Such serial ports use this mode to implement unidirectional flow control. The serial port will suspend transmission when requested by the modem (via CTS) but will be unable to request the modem stop sending to the computer. This mode retains the ability to use DTR as a modem control line.
- defaultroute
当IPCP协商完全成功时，增加一个预设递送路径到系统的递送表，将彼端当作闸道器使用。这个项目在ppp连线中断後会移除。- disconnectscript
在pppd已经终结该连线之後执行以所指定的可执行指令或是shell指令。这个指令稿可以用来，例如，如果硬体的数据机控制信号无法使用时，发出指令给数据机使其挂断电话。 The disconnect script is not run if the modem has already hung up. A value for this option from a privileged source cannot be overridden by a non-privileged user.- escapexx,yy,...
指定在传输上确实应该要避开的字元（不管对方是否有用它的非同步控制字元对照表要求避开它们）。这些要被避开的字元是以用逗号隔开的一串十六进位数字指定的。要注意到几乎任何字元都可以用escape选项指定避开，不像asyncmap选项只允许指定控制字元。不能避开的字元是那些有十六进位值0x20-0x3f或是0x5e者。- filename
从档案里读取选项（其格式叙述在後） The file must be readable by the user who has invoked pppd.- initscript
- Run the executable or shell command specified byscript to initialize the serial line. This script would typically use the chat(8) program to configure the modem to enable auto answer. A value for this option from a privileged source cannot be overridden by a non-privileged user.
- lock
- 指定pppd应该在此串列设备上使用UUCP式的锁定以确定对该设备为互斥(exclusive)存取。
- mrun
- 把MRU[MaximumReceiveUnit最大接收单元]的值设为 n来进行协商。pppd将会要求彼端传送不比位元组更长的封包。最小的MRU值是128。预设的MRU值则是 1500。对於慢速线路上的建议值是296（其中40个位元组给TCP/IP表头+256个位元组的资料）。
(Note that for IPv6 MRU must be at least 1280) - mtun
将MTU[MaximumTransmitUnit最大传输单元]的值设为n。除非彼端经由MRU协商要求一个更小的值，pppd 将会要求核心网路程式码透过PPP网路界面所传送的资料封包不超过n个位元组。
(Note that for IPv6 MTU must be at least 1280)- passive
在LCP中开启"passive"选项。加上这个选项，pppd将会试图初使一个连线；如果没有从彼端接收到回应，那麽 pppd将只会被动地等待从彼端所传来的一个有效LCP封包（代替结束离开，就像它在没有这个选项时所作的）。
选项 OPTIONS
- <local_IP_address>:<remote_IP_address>
设定本地以及／或是远端界面的IP位址。两者之中的任何一个都可以省略。该IP位址可以利用主机名称或者是十进位数值加小数点符号指定(e.g.150.234.56.78)。预设的本地位址是系统的（第一个）IP位址（除非有加上 noipdefault选项）。远端位址如果没有在任何选项中指定的话将从彼端取得。因此，在简单的案例中，这个选项不是必须的。如果有一个本地以及／或是远端的IP位址以这个选项加以指定的话，pppd将不会接受在IPCP协商中从彼端所传来不同的值，除非加上ipcp-accept-local 以及／或是ipcp-accept-remote选项，个别地。- ipv6<local_interface_identifier>,<remote_interface_identifier>
- Set the local and/or remote 64-bit interface identifier. Either one may be omitted. The identifier must be specified in standard ascii notation of IPv6 addresses (e.g. ::dead:beef). If the ipv6cp-use-ipaddr option is given, the local identifier is the local IPv4 address (see above). On systems which supports a unique persistent id, such as EUI-48 derived from the Ethernet MAC address,ipv6cp-use-persistent option can be used to replace the ipv6 <local>,<remote> option. Otherwise the identifier is randomized.
- active-filterfilter-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 theidleoption 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. Thefilter-expression syntax is as described for tcpdump(1), except that qualifiers which are inappropriate for a PPP link, such asether andarp, 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. This option is currently only available under NetBSD, and then only if both the kernel and pppd were compiled with PPP_FILTER defined.
- allow-ipaddress(es)
- Allow peers to use the given IP address or subnet without authenticating themselves. The parameter is parsed as for each element of the list of allowed IP addresses in the secrets files (see the AUTHENTICATION section below).
- bsdcompnr,nt
- Request that the peer compress packets that it sends, using the BSD-Compress scheme, with a maximum code size ofnr bits, and agree to compress packets sent to the peer with a maximum code size ofnt bits. If nt is not specified, it defaults to the value given fornr. Values in the range 9 to 15 may be used for nr and nt; larger values give better compression but consume more kernel memory for compression dictionaries. Alternatively, a value of 0 fornr or nt disables compression in the corresponding direction. Usenobsdcomp or bsdcomp 0 to disable BSD-Compress compression entirely.
- cdtrcts
- Use a non-standard hardware flow control (i.e. DTR/CTS) to control the flow of data on the serial port. If neither thecrtscts, the nocrtscts, the cdtrcts nor thenocdtrcts option is given, the hardware flow control setting for the serial port is left unchanged. Some serial ports (such as Macintosh serial ports) lack a true RTS output. Such serial ports use this mode to implement true bi-directional flow control. The sacrifice is that this flow control mode does not permit using DTR as a modem control line.
- chap-intervaln
如果有给这个选项，pppd将会每n 秒重新盘查彼端。- chap-max-challengen
将CHAP盘查(challenge)传输的最大数目设为n（预设为10）。- chap-restartn
将CHAP重新开始的间隔（重新传输的时间限制）设为n 秒钟（预设为3）。- connect-delayn
- Wait for upn milliseconds after the connect script finishes for a valid PPP packet from the peer. At the end of this time, or when a valid PPP packet is received from the peer, pppd will commence negotiation by sending its first LCP packet. The default value is 1000 (1 second). This wait period only applies if the connect orptyoption is used.
- debug
- 递增侦错层级（与-d相同）。如果加上这个选项，pppd 将以可供阅读的格式记录所有传送或接收的控制封包内容。这些封包透过syslog以facilitydaemon还有level debug加以记录。该资讯可以适当设定/etc/syslog.conf 来导向到一个档案去。（参阅syslog.conf(5)）。(如果 pppd以开启扩充侦错(extradebugging)编译的话，它将会使用facilitylocal2取代daemon来记录讯息）。
- default-asyncmap
- Disable asyncmap negotiation, forcing all control characters to be escaped for both the transmit and the receive direction.
- default-mru
- Disable MRU [Maximum Receive Unit] negotiation. With this option, pppd will use the default MRU value of 1500 bytes for both the transmit and receive direction.
- deflatenr,nt
- Request that the peer compress packets that it sends, using the Deflate scheme, with a maximum window size of2**nr bytes, and agree to compress packets sent to the peer with a maximum window size of2**nt bytes. If nt is not specified, it defaults to the value given fornr. Values in the range 9 to 15 may be used for nr and nt; larger values give better compression but consume more kernel memory for compression dictionaries. Alternatively, a value of 0 fornr or nt disables compression in the corresponding direction. Usenodeflate ordeflate 0 to disable Deflate compression entirely. (Note: pppd requests Deflate compression in preference to BSD-Compress if the peer can do either.)
- demand
- Initiate the link only on demand, i.e. when data traffic is present. With this option, the remote IP address must be specified by the user on the command line or in an options file. Pppd will initially configure the interface and enable it for IP traffic without connecting to the peer. When traffic is available, pppd will connect to the peer and perform negotiation, authentication, etc. When this is completed, pppd will commence passing data packets (i.e., IP packets) across the link.
The demand option implies thepersist option. If this behaviour is not desired, use the nopersist option after thedemand option. The idle and holdoff options are also useful in conjuction with thedemand option.
- domaind
新增领域名称到本地主机名称以支援验证。例如，如果gethostname()回应porsche这个名称，但是完整合格的领域名称是porsche.Quotron.COM的话，你可以使用 domain选项来将领域名称设为Quotron.COM。
Pppd would then use the name porsche.Quotron.COM for looking up secrets in the secrets file, and as the default name to send to the peer when authenticating itself to the peer. This option is privileged.- dryrun
- With thedryrun option, pppd will print out all the option values which have been set and then exit, after parsing the command line and options files and checking the option values, but before initiating the link. The option values are logged at level info, and also printed to standard output unless the device on standard output is the device that pppd would be using to communicate with the peer.
- dump
- With thedump option, pppd will print out all the option values which have been set. This option is like thedryrun option except that pppd proceeds as normal rather than exiting.
- endpoint<epdisc>
- Sets the endpoint discriminator sent by the local machine to the peer during multilink negotiation to<epdisc>. The default is to use the MAC address of the first ethernet interface on the system, if any, otherwise the IPv4 address corresponding to the hostname, if any, provided it is not in the multicast or locally-assigned IP address ranges, or the localhost address. The endpoint discriminator can be the string null or of the formtype:value, where type is a decimal number or one of the stringslocal, IP, MAC, magic, orphone. The value is an IP address in dotted-decimal notation for theIP type, or a string of bytes in hexadecimal, separated by periods or colons for the other types. For the MAC type, the value may also be the name of an ethernet or similar network interface. This option is currently only available under Linux.
- hide-password
- When logging the contents of PAP packets, this option causes pppd to exclude the password string from the log. This is the default.
- holdoffn
- Specifies how many seconds to wait before re-initiating the link after it terminates. This option only has any effect if thepersist or demand option is used. The holdoff period is not applied if the link was terminated because it was idle.
- idlen
- Specifies that pppd should disconnect if the link is idle forn seconds. The link is idle when no data packets (i.e. IP packets) are being sent or received. Note: it is not advisable to use this option with thepersist option without the demand option. If the active-filteroption is given, data packets which are rejected by the specified activity filter also count as the link being idle.
- ipcp-accept-local
- 加上这个选项的话，pppd将会接受彼端对於本地IP位址的意见，即使本地的IP位址已经在某个选项中指定。
- ipcp-accept-remote
- 加上这个选项的话，pppd将会接受彼端对於它的IP位址的意见，即使远端的IP位址已经在某个选项中指定。
- ipcp-max-configuren
将IPCP配置要求(configure-request)传输的最大数目设为n（预设为10）。- ipcp-max-failuren
- 将开始传送配置拒绝(configure-Rejects)之前的IPCP配置未接收(configure-NAKs)的最大数目以取代n（预设为10）。
- ipcp-max-terminaten
将IPCP终结要求(terminate-request)传输的最大数目设为 n（预设为3）。- ipcp-restartn
将IPCP重新开始的间隔（重新传输的时间限制）设为n 秒钟（预设为3）。- ipparamstring
- Provides an extra parameter to the ip-up and ip-down scripts. If this option is given, thestring supplied is given as the 6th parameter to those scripts.
- ipv6cp-max-configuren
- Set the maximum number of IPv6CP configure-request transmissions ton (default 10).
- ipv6cp-max-failuren
- Set the maximum number of IPv6CP configure-NAKs returned before starting to send configure-Rejects instead ton (default 10).
- ipv6cp-max-terminaten
- Set the maximum number of IPv6CP terminate-request transmissions ton (default 3).
- ipv6cp-restartn
- Set the IPv6CP restart interval (retransmission timeout) ton seconds (default 3).
- ipx
- Enable the IPXCP and IPX protocols. This option is presently only supported under Linux, and only if your kernel has been configured to include IPX support.
- ipx-networkn
- Set the IPX network number in the IPXCP configure request frame ton, a hexadecimal number (without a leading 0x). There is no valid default. If this option is not specified, the network number is obtained from the peer. If the peer does not have the network number, the IPX protocol will not be started.
- ipx-noden:m
- Set the IPX node numbers. The two node numbers are separated from each other with a colon character. The first numbern is the local node number. The second number m is the peer's node number. Each node number is a hexadecimal number, at most 10 digits long. The node numbers on the ipx-network must be unique. There is no valid default. If this option is not specified then the node numbers are obtained from the peer.
- ipx-router-name<string>
- Set the name of the router. This is a string and is sent to the peer as information data.
- ipx-routingn
- Set the routing protocol to be received by this option. More than one instance ofipx-routing may be specified. 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-configuren
- Set the maximum number of IPXCP configure request frames which the system will send ton. The default is 10.
- ipxcp-max-failuren
- Set the maximum number of IPXCP NAK frames which the local system will send before it rejects the options. The default value is 3.
- ipxcp-max-terminaten
- 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.
- kdebugn
- 开启核心层级中的PPP驱动程式侦错码。The argument values depend on the specific kernel driver, but in general a value of 1 will enable general kernel debug messages. (Note that these messages are usually only useful for debugging the kernel driver itself.) For the Linux 2.2.x kernel driver, 参数n是一个由下列值所组合的数字：1开启一般侦错讯息，2要求印出所接收到的封包内容，而4要求印出传输的封包内容。 On most systems, messages printed by the kernel are logged by syslog(1) to a file as directed in the /etc/syslog.conf configuration file.
- ktune
- Enables pppd to alter kernel settings as appropriate. Under Linux, pppd will enable IP forwarding (i.e. set /proc/sys/net/ipv4/ip_forward to 1) if theproxyarp option is used, and will enable the dynamic IP address option (i.e. set /proc/sys/net/ipv4/ip_dynaddr to 1) in demand mode if the local address changes.
- lcp-echo-failuren
如果有给这个选项，那麽如果传送n个LCP回应要求没有接收到有效的LCP回应回覆的话pppd将会推测彼端是死掉的。如果发生这种情形，pppd将会终结该连线。这个选项的使用要求一个非零的lcp-echo-interval参数值。这个选项可以用在硬体数据机控制线路无法使用的情况下当实际连线被中断之後（e.g.,数据机已经挂断）终结 pppd的执行。- lcp-echo-intervaln
- 如果有给这个选项，pppd每秒将会送出一个LCP回应要求(echo-request)封包(frame)给彼端。在Linux系统下，回应要求在n秒内没有从彼端接收到封包时会被送出。一般彼端应该以传送一个回应回覆(echo-reply)来反应该回应要求。这个选项可以与lcp-echo-failure选项一起使用来侦测不再连线的彼端。
- lcp-max-configuren
将LCP配置要求(configure-request)传输的最大数目设为n（预设为10）。- lcp-max-failuren
将开始传送配置拒绝(configure-Rejects)之前的LCP配置未接收(configure-NAKs)的最大数目设置为n（预设为10）。- lcp-max-terminaten
将LCP终结要求(terminate-request)传输的最大数目设为n（预设为3）。- lcp-restartn
- 将LCP重新开始的间隔（重新传输的时间限制）设为秒钟（预设为3）。
- linknamename
- Sets the logical name of the link toname. Pppd will create a file namedppp-name.pid in /var/run (or /etc/ppp on some systems) containing its process ID. This can be useful in determining which instance of pppd is responsible for the link to a given peer system. This is a privileged option.
- local
- 不要使用数据机控制线路。 With this option, pppd will ignore the state of the CD (Carrier Detect) signal from the modem and will not change the state of the DTR (Data Terminal Ready) signal.
- logfdn
- Send log messages to file descriptorn. Pppd will send log messages to at most one file or file descriptor (as well as sending the log messages to syslog), so this option and thelogfile option are mutually exclusive. The default is for pppd to send log messages to stdout (file descriptor 1), unless the serial port is already open on stdout.
- logfilefilename
- Append log messages to the filefilename (as well as sending the log messages to syslog). The file is opened with the privileges of the user who invoked pppd, in append mode.
- login
- 使用系统密码资料库验证使用PAP的彼端。 and record the user in the system wtmp file. Note that the peer must have an entry in the /etc/ppp/pap-secrets file as well as the system password database to be allowed access.
- maxconnectn
- Terminate the connection when it has been available for network traffic forn seconds (i.e. n seconds after the first network control protocol comes up).
- maxfailn
- Terminate aftern consecutive failed connection attempts. A value of 0 means no limit. The default value is 10.
- modem
- 使用数据机控制线路。This option is the default. With this option, pppd will wait for the CD (Carrier Detect) signal from the modem to be asserted when opening the serial device (unless a connect script is specified), and it will drop the DTR (Data Terminal Ready) signal briefly when the connection is terminated and before executing the connect script. 在Ultrix上，这个选项会实作硬体流量控制，像crtsct选项作的。
- mp
- Enables the use of PPP multilink; this is an alias for the `multilink' option. This option is currently only available under Linux.
- mpshortseq
- Enables the use of short (12-bit) sequence numbers in multilink headers, as opposed to 24-bit sequence numbers. This option is only available under Linux, and only has any effect if multilink is enabled (see the multilink option).
- mrrun
- Sets the Maximum Reconstructed Receive Unit ton. The MRRU is the maximum size for a received packet on a multilink bundle, and is analogous to the MRU for the individual links. This option is currently only available under Linux, and only has any effect if multilink is enabled (see the multilink option).
- ms-dns<addr>
- If pppd is acting as a server for Microsoft Windows clients, this option allows pppd to supply one or two DNS (Domain Name Server) addresses to the clients. The first instance of this option specifies the primary DNS address; the second instance (if given) specifies the secondary DNS address. (This option was present in some older versions of pppd under the namedns-addr.)
- ms-wins<addr>
- If pppd is acting as a server for Microsoft Windows or "Samba" clients, this option allows pppd to supply one or two WINS (Windows Internet Name Services) server addresses to the clients. The first instance of this option specifies the primary WINS address; the second instance (if given) specifies the secondary WINS address.
- multilink
- Enables the use of the PPP multilink protocol. If the peer also supports multilink, then this link can become part of a bundle between the local system and the peer. If there is an existing bundle to the peer, pppd will join this link to that bundle, otherwise pppd will create a new bundle. See the MULTILINK section below. This option is currently only available under Linux.
- namename
- 将本地系统的名称设为用来进行验证。 This is a privileged option. With this option, pppd will use lines in the secrets files which havename as the second field when looking for a secret to use in authenticating the peer. In addition, unless overridden with theuser option,name will be used as the name to send to the peer when authenticating the local system to the peer. (Note that pppd does not append the domain name toname.)
- netmaskn
把该界面网路掩码设为，这是一个以″十进位数值加小数点″("decimaldot")符号表示的32位元网路掩码 (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. (Note: on some platforms, pppd will always use 255.255.255.255 for the netmask, if that is the only appropriate value for a point-to-point interface.)- noaccomp
- Disable Address/Control compression in both directions (send and receive).
- noauth
- Do not require the peer to authenticate itself. This option is privileged.
- nobsdcomp
- Disables BSD-Compress compression;pppd will not request or agree to compress packets using the BSD-Compress scheme.
- noccp
- Disable CCP (Compression Control Protocol) negotiation. This option should only be required if the peer is buggy and gets confused by requests from pppd for CCP negotiation.
- nocrtscts
- Disable hardware flow control (i.e. RTS/CTS) on the serial port. If neither thecrtscts nor thenocrtscts nor the cdtrcts nor the nocdtrcts option is given, the hardware flow control setting for the serial port is left unchanged.
- nocdtrcts
- This option is a synonym fornocrtscts. Either of these options will disable both forms of hardware flow control.
- nodefaultroute
- Disable thedefaultroute option. The system administrator who wishes to prevent users from creating default routes with pppd can do so by placing this option in the /etc/ppp/options file.
- nodeflate
- Disables Deflate compression; pppd will not request or agree to compress packets using the Deflate scheme.
- nodetach
- Don't detach from the controlling terminal. Without this option, if a serial device other than the terminal on the standard input is specified, pppd will fork to become a background process.
- noendpoint
- Disables pppd from sending an endpoint discriminator to the peer or accepting one from the peer (see the MULTILINK section below). This option should only be required if the peer is buggy.
- noip
- Disable IPCP negotiation and IP communication. This option should only be required if the peer is buggy and gets confused by requests from pppd for IPCP negotiation.
- noipv6
- Disable IPv6CP negotiation and IPv6 communication. This option should only be required if the peer is buggy and gets confused by requests from pppd for IPv6CP negotiation.
- noipdefault
- 关闭在没有指定本地IP位址时所进行的预设动作，这是用来由从主机名称决定（如果可能的话）决定本地IP位址。加上这个选项的话，彼端将必须在进行IPCP协商时（除非在指令列或在选项档中明确地指定它）提供本地的 IP位址。
- noipx
- Disable the IPXCP and IPX protocols. This option should only be required if the peer is buggy and gets confused by requests from pppd for IPXCP negotiation.
- noktune
- Opposite of thektune option; disables pppd from changing system settings.
- nolog
- Do not send log messages to a file or file descriptor. This option cancels thelogfdand logfile options.
- nomagic
- Disable magic number negotiation. With this option, pppd cannot detect a looped-back line. This option should only be needed if the peer is buggy.
- nomp
- Disables the use of PPP multilink. This option is currently only available under Linux.
- nompshortseq
- Disables the use of short (12-bit) sequence numbers in the PPP multilink protocol, forcing the use of 24-bit sequence numbers. This option is currently only available under Linux, and only has any effect if multilink is enabled.
- nomultilink
- Disables the use of PPP multilink. This option is currently only available under Linux.
- nopcomp
- Disable protocol field compression negotiation in both the receive and the transmit direction.
- nopersist
- Exit once a connection has been made and terminated. This is the default unless thepersist ordemand option has been specified.
- nopredictor1
- Do not accept or agree to Predictor-1 compression.
- noproxyarp
- Disable theproxyarp option. The system administrator who wishes to prevent users from creating proxy ARP entries with pppd can do so by placing this option in the /etc/ppp/options file.
- notty
- Normally, pppd requires a terminal device. With this option, pppd will allocate itself a pseudo-tty master/slave pair and use the slave as its terminal device. Pppd will create a child process to act as a `character shunt' to transfer characters between the pseudo-tty master and its standard input and output. Thus pppd will transmit characters on its standard output and receive characters on its standard input even if they are not terminal devices. This option increases the latency and CPU overhead of transferring data over the ppp interface as all of the characters sent and received must flow through the character shunt process. An explicit device name may not be given if this option is used.
- novj
- Disable Van Jacobson style TCP/IP header compression in both the transmit and the receive direction.
- novjccomp
- Disable the connection-ID compression option in Van Jacobson style TCP/IP header compression. With this option, pppd will not omit the connection-ID byte from Van Jacobson compressed TCP/IP headers, nor ask the peer to do so.
- 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 pppd should not accept a password which, before encryption, is identical to the secret from the /etc/ppp/pap-secrets file.
- pap-max-authreqn
将PAP验证要求(authenticate-request)传输的最大数目设为n（预设为10）。- pap-restartn
将PAP重新开始的间隔（重新传输的时间限制）设为n 秒钟（预设为3）。- pap-timeoutn
- Set the maximum time that pppd will wait for the peer to authenticate itself with PAP ton seconds (0 means no limit).
- pass-filterfilter-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. Thefilter-expression syntax is as described for tcpdump(1), except that qualifiers which are inappropriate for a PPP link, such asether 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 andoutbound qualifiers. This option is currently only available under NetBSD, and then only if both the kernel and pppd were compiled with PPP_FILTER defined.
- persist
- Do not exit after a connection is terminated; instead try to reopen the connection.
- pluginfilename
- Load the shared library object filefilename as a plugin. This is a privileged option.
- predictor1
- Request that the peer compress frames that it sends using Predictor-1 compression, and agree to compress transmitted frames with Predictor-1 if requested. This option has no effect unless the kernel driver supports Predictor-1 compression.
- privgroupgroup-name
- Allows members of groupgroup-name to use privileged options. This is a privileged option. Use of this option requires care as there is no guarantee that members ofgroup-name cannot use pppd to become root themselves. Consider it equivalent to putting the members ofgroup-name in the kmem or disk group.
- proxyarp
- 以彼端的IP位址以及该系统的乙太网路位址增加一个项目到系统的ARP[AddressResolutionProtocol位址解译协定]表格。 This will have the effect of making the peer appear to other systems to be on the local ethernet.
- ptyscript
- Specifies that the commandscript is to be used to communicate rather than a specific terminal device. Pppd will allocate itself a pseudo-tty master/slave pair and use the slave as its terminal device. Thescript will be run in a child process with the pseudo-tty master as its standard input and output. An explicit device name may not be given if this option is used. (Note: if therecord option is used in conjuction with the pty option, the child process will have pipes on its standard input and output.)
- receive-all
- With this option, pppd will accept all control characters from the peer, including those marked in the receive asyncmap. Without this option, pppd will discard those characters as specified in RFC1662. This option should only be needed if the peer is buggy.
- recordfilename
- Specifies that pppd should record all characters sent and received to a file namedfilename. This file is opened in append mode, using the user's user-ID and permissions. This option is implemented using a pseudo-tty and a process to transfer characters between the pseudo-tty and the real serial device, so it will increase the latency and CPU overhead of transferring data over the ppp interface. The characters are stored in a tagged format with timestamps, which can be displayed in readable form using the pppdump(8) program.
- remotenamename
- 将远端系统的假设名称设为以进行验证。
- refuse-chap
- With this option, pppd will not agree to authenticate itself to the peer using CHAP.
- refuse-pap
- With this option, pppd will not agree to authenticate itself to the peer using PAP.
- require-chap
- Require the peer to authenticate itself using CHAP [Challenge Handshake Authentication Protocol] authentication.
- require-pap
- Require the peer to authenticate itself using PAP [Password Authentication Protocol] authentication.
- show-password
- When logging the contents of PAP packets, this option causes pppd to show the password string in the log message.
- silent
- 加上这个选项，pppd将不会传输LCP封包来初使一个连线一直到从彼端接收到一个有效的LCP封包。（就像是给旧版pppd使用的"passive"选项）。
- sync
- Use synchronous HDLC serial encoding instead of asynchronous. The device used by pppd with this option must have sync support. Currently supports Microgate SyncLink adapters under Linux and FreeBSD 2.2.8 and later.
- updetach
- With this option, pppd will detach from its controlling terminal once it has successfully established the ppp connection (to the point where the first network control protocol, usually the IP control protocol, has come up).
- usehostname
- 强迫主机名称使用本地系统的名称来进行验证。（这会盖过name选项）。 This option is not normally needed since thename option is privileged.
- usepeerdns
- Ask the peer for up to 2 DNS server addresses. The addresses supplied by the peer (if any) are passed to the /etc/ppp/ip-up script in the environment variables DNS1 and DNS2. In addition, pppd will create an /etc/ppp/resolv.conf file containing one or two nameserver lines with the address(es) supplied by the peer.
- username
- 将使用者名称设为以便让使用PAP的彼端验证这台机器时使用。
- vj-max-slotsn
- Sets the number of connection slots to be used by the Van Jacobson TCP/IP header compression and decompression code ton, which must be between 2 and 16 (inclusive).
- welcomescript
- Run the executable or shell command specified byscript before initiating PPP negotiation, after the connect script (if any) has completed. A value for this option from a privileged source cannot be overridden by a non-privileged user.
- xonxoff
- 使用软体流量控制(i.e.XON/XOFF)来控制串列埠上的资料流。
选项文件 OPTIONS FILES
选项可以从档案取出使用就如同使用命令列一般。pppd在查看指令列之前先从档案/etc/ppp/options以及~/.ppprc读取选项。ttyname (in that order) before processing the options on the command line. (In fact, the command-line options are scanned to find the terminal name before the options.ttyname file is read.) In forming the name of the options.ttyname file, the initial /dev/ is removed from the terminal name, and any remaining / characters are replaced with dots.
一个选项档案以空白字元为界被剖析成一串单字。空白字元可以用双引号(")包括在一个单字里。倒斜线引用其後的字元。而hash (#)符号开始一段注解持续到该行结束。 There is no restriction on using thefile or call options within an options file.
安全 SECURITY
pppd 提供系统管理人员充份的存取控制能力这表示以PPP存取一台伺服机器可以提供给合法的使用者使用而不必担心危及该伺服器或所在网路的安全性。这有一部份是以/etc/ppp/options档案来提供，在这里系统管理人员可以放置在执行pppd的时候用来要求验证的选项，而部份是由PAP以及CHAP暗号档案来提供，其中系统管理人员可以限制个别的使用者可以使用的一群IP位址。
The default behaviour of pppd is to allow an unauthenticated peer to use a given IP address only if the system does not already have a route to that IP address. For example, a system with a permanent connection to the wider internet will normally have a default route, and thus all peers will have to authenticate themselves in order to set up a connection. On such a system, theauth option is the default. On the other hand, a system where the PPP link is the only connection to the internet will not normally have a default route, so the peer will be able to use almost any IP address without authenticating itself.
As indicated above, some security-sensitive options are privileged, which means that they may not be used by an ordinary non-privileged user running a setuid-root pppd, either on the command line, in the user's ~/.ppprc file, or in an options file read using thefile option. Privileged options may be used in /etc/ppp/options file or in an options file read using thecall option. If pppd is being run by the root user, privileged options can be used without restriction.
When opening the device, pppd uses either the invoking user's user ID or the root UID (that is, 0), depending on whether the device name was specified by the user or the system administrator. If the device name comes from a privileged source, that is, /etc/ppp/options or an options file read using thecall option, pppd uses full root privileges when opening the device. Thus, by creating an appropriate file under /etc/ppp/peers, the system administrator can allow users to establish a ppp connection via a device which they would not normally have permission to access. Otherwise pppd uses the invoking user's real UID when opening the device.
AUTHENTICATION
Authentication is the process whereby one peer convinces the other of its identity. This involves the first peer sending its name to the other, together with some kind of secret information which could only come from the genuine authorized user of that name. In such an exchange, we will call the first peer the "client" and the other the "server". The client has a name by which it identifies itself to the server, and the server also has a name by which it identifies itself to the client. Generally the genuine client shares some secret (or password) with the server, and authenticates itself by proving that it knows that secret. Very often, the names used for authentication correspond to the internet hostnames of the peers, but this is not essential.
At present, pppd supports two authentication protocols: the Password Authentication Protocol (PAP) and the Challenge Handshake Authentication Protocol (CHAP). PAP involves the client sending its name and a cleartext password to the server to authenticate itself. In contrast, the server initiates the CHAP authentication exchange by sending a challenge to the client (the challenge packet includes the server's name). The client must respond with a response which includes its name plus a hash value derived from the shared secret and the challenge, in order to prove that it knows the secret.
The PPP protocol, being symmetrical, allows both peers to require the other to authenticate itself. In that case, two separate and independent authentication exchanges will occur. The two exchanges could use different authentication protocols, and in principle, different names could be used in the two exchanges.
pppd预设的动作是如果有要求就同意进行验证，并且不要求从彼端做验证。然而如果没有可以用来验证的暗号则pppd将不会同意以特殊的协定来验证它自己。
验证的基础是由暗号档案选择的暗号（/etc/ppp/pap-secrets是给PAP使用的，/etc/ppp/chap-secrets则是给CHAP使用）。这两个暗号档案都具有相同的格式，而且两者都可以储放暗号给数种伺服器（验证彼端）及客户（被验证端）组合使用。注意pppd 可以最为伺服端以及客户端，而且如果需要的话两方可以使用不同的协定。
一个暗号档案如同选项档案一般被剖析成单字。一个暗号是由最少包含3个单字的一行所指定，依序是客户，伺服器，暗号。在同一行中任何跟在其後的单字都被当作是给客户的可接受IP位址列表。如果该行只有3个单字，这假设任何IP位址都可以；不允许所有的IP位址的话，使用"-"。如果暗号是以'@'开始，其後所接的单字将被假设为可以从中读取暗号的档案名称。而以一个 "*"字元作为客户或伺服端的名称会符合任何名称。在选择一个暗号时，pppd会选择最符合的，i.e.最少万用字元的那个。
如此一个暗号档案包含用来验证其它主机，以及用来为其它主机验证自己两者的暗号。选择使用哪个暗号是根据该主机（’本地名称 ’）以及其彼端（’远端名称’）而定。本地名称的设定如下：
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, pppd takes the best match, i.e. the match with the fewest wildcards.
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, or if the first word is "-", then all IP addresses are disallowed. To allow any address, use "*". A word starting with "!" indicates that the specified address isnot acceptable. An address may be followed by "/" and a number n, to indicate a whole subnet, i.e. all addresses which have the same value in the most significantn bits. In this form, the address may be followed by a plus sign ("+") to indicate that one address from the subnet is authorized, based on the ppp network interface unit number in use. In this case, the host part of the address will be set to the unit number plus one.
Thus a secrets file contains both secrets for use in authenticating other hosts, plus secrets which we use for authenticating ourselves to others. When pppd is authenticating the peer (checking the peer's identity), it chooses a secret with the peer's name in the first field and the name of the local system in the second field. The name of the local system defaults to the hostname, with the domain name appended if thedomain option is used. This default can be overridden with the name option, except when theusehostname option is used.
When pppd is choosing a secret to use in authenticating itself to the peer, it first determines what name it is going to use to identify itself to the peer. This name can be specified by the user with theuser option. If this option is not used, the name defaults to the name of the local system, determined as described in the previous paragraph. Then pppd looks for a secret with this name in the first field and the peer's name in the second field. Pppd will know the name of the peer if CHAP authentication is being used, because the peer will have sent it in the challenge packet. However, if PAP is being used, pppd will have to determine the peer's name from the options specified by the user. The user can specify the peer's name directly with the remotename option. Otherwise, if the remote IP address was specified by a name (rather than in numeric form), that name will be used as the peer's name. Failing that, pppd will use the null string as the peer's name.
当以PAP验证彼端时，一个""暗号符合任何由彼端所提供密码。如果密码不符合暗号，密码被以crypt()编码并且再次检查暗号；因此验证彼端的暗号可以编码方式储放。
如果指定有login选项，使用者名称以及密码也会被以系统的密码资料库检查。因此系统管理人员可以设定pap-secrets档案以便只允许某些使用者以PPP 连线，并且限制每个使用者可以使用一些IP位址。 Typically, when using thelogin option, the secret in /etc/ppp/pap-secrets would be "", which will match any password supplied by the peer. This avoids the need to have the same secret in two places.
验证必须在IPCP（或任何其它网路控制协定）开始之前被完全地满足。如果验证失败，pppd将会终结连线（关闭LCP）。如果 IPCP协商出一个无法接受的远端主机IP位址，IPCP将会关闭。 IP封包只有在IPCP打开的时候才能传送或接收。
即使本地主机一般会要求验证，在某些案例中会希望允一些无法验证它们自己的主机连线并使用所限制的IP位址其中之一。如果彼在被要求时拒绝验证它自己，pppd将会把它当成等於是在使用者名称以及密码上使用空字串来以PAP验证。所以，藉由增加一行指定空字串为客户以及密码到pap-secrets档案去，允许拒绝验证自己的主机进行有限制的存取是可能的。
路由 ROUTING
当IPCP协商成功地完成时，pppd将会通知核心该ppp界面本地以及远端的IP位址。这足够用来建立一个主机到该连线远端的递送路径，该路径将使两端能交换IP封包。与其它的机器进行通讯往往需要更进一步地修改递送表格(routingtables)以及／或是 ARP（位址解译协定）表格。在某些案例中这将透过routed或是 gated隐形程式的动作自动地完成，但是在大部分的案例中需要更进一步的介入。
有时候会希望透过远端主机来增加一个预设递送路径，像是在一台只透过ppp界面连线到Internet的机器。此defaultroute选项使得pppd在IPCP完成时建立起这麽一个预设的递送路径，并且在该线路被终结时将之删除。
在某些情况下会希望使用proxyARP，例如在一台连结到区域网路的伺服机器上，为了能够允许其它的主机与远端主机进行通讯。 proxyarp选项引发pppd去寻找一个与远端主机在相同子网路上的网路界面（一个支援广播(boardcast)以及ARP的界面，不但要是可用的并且不是一个点对点或回授界面）。如果找到，pppd会以该远端主机的IP位址以及所找到的网路界面之硬体位址建立一个永久的，公开的ARP项目。
When the demand option is used, the interface IP addresses have already been set at the point when IPCP comes up. If pppd has not been able to negotiate the same addresses that it used to configure the interface (for example when the peer is an ISP that uses dynamic IP address assignment), pppd has to change the interface IP addresses to the negotiated addresses. This may disrupt existing connections, and the use of demand dialling with peers that do dynamic IP address assignment is not recommended.
MULTILINK
Multilink PPP provides the capability to combine two or more PPP links between a pair of machines into a single `bundle', which appears as a single virtual PPP link which has the combined bandwidth of the individual links. Currently, multilink PPP is only supported under Linux.
Pppd detects that the link it is controlling is connected to the same peer as another link using the peer's endpoint discriminator and the authenticated identity of the peer (if it authenticates itself). The endpoint discriminator is a block of data which is hopefully unique for each peer. Several types of data can be used, including locally-assigned strings of bytes, IP addresses, MAC addresses, randomly strings of bytes, or E-164 phone numbers. The endpoint discriminator sent to the peer by pppd can be set using the endpoint option.
In circumstances the peer may send no endpoint discriminator or a non-unique value. The optional bundle option adds an extra string which is added to the peer's endpoint discriminator and authenticated identity when matching up links to be joined together in a bundle. The bundle option can also be used to allow the establishment of multiple bundles between the local system and the peer. Pppd uses a TDB database in /var/run/pppd.tdb to match up links.
Assuming that multilink is enabled and the peer is willing to negotiate multilink, then when pppd is invoked to bring up the first link to the peer, it will detect that no other link is connected to the peer and create a new bundle, that is, another ppp network interface unit. When another pppd is invoked to bring up another link to the peer, it will detect the existing bundle and join its link to it. Currently, if the first pppd terminates (for example, because of a hangup or a received signal) the bundle is destroyed.
范例 EXAMPLES
The following examples assume that the /etc/ppp/options file contains theauthoption (as in the default /etc/ppp/options file in the ppp distribution).
Probably the most common use of pppd is to dial out to an ISP. This can be done with a command such as
- pppd call isp
where the /etc/ppp/peers/isp file is set up by the system administrator to contain something like this:
- ttyS0 19200 crtscts
connect '/usr/sbin/chat -v -f /etc/ppp/chat-isp'
noauth
In this example, we are using chat to dial the ISP's modem and go through any logon sequence required. The /etc/ppp/chat-isp file contains the script used by chat; it could for example contain something like this:
- ABORT "NO CARRIER"
ABORT "NO DIALTONE"
ABORT "ERROR"
ABORT "NO ANSWER"
ABORT "BUSY"
ABORT "Username/Password Incorrect"
"" "at"
OK "at&d0&c1"
OK "atdt2468135"
"name:" "^Umyuserid"
"word:" "\qmypassword"
"ispts" "\q^Uppp"
"~-^Uppp-~"
See the chat(8) man page for details of chat scripts.
Pppd can also be used to provide a dial-in ppp service for users. If the users already have login accounts, the simplest way to set up the ppp service is to let the users log in to their accounts and run pppd (installed setuid-root) with a command such as
- pppd proxyarp
To allow a user to use the PPP facilities, you need to allocate an IP address for that user's machine and create an entry in /etc/ppp/pap-secrets or /etc/ppp/chap-secrets (depending on which authentication method the PPP implementation on the user's machine supports), so that the user's machine can authenticate itself. For example, if Joe has a machine called "joespc" which is to be allowed to dial in to the machine called "server" and use the IP address joespc.my.net, you would add an entry like this to /etc/ppp/pap-secrets or /etc/ppp/chap-secrets:
- joespcserver "joe's secret" joespc.my.net
Alternatively, you can create a username called (for example) "ppp", whose login shell is pppd and whose home directory is /etc/ppp. Options to be used when pppd is run this way can be put in /etc/ppp/.ppprc.
如果你的串列连线比直接以线路连接更复杂的话，你可能会需要做些调整以便避开一些控制字元。特别是，通常避开XON(^Q)以及 XOFF(^S)是有用的，可以使用asyncmapa0000。如果该路径包含telnet的话，你可能应该也要避开^](asyncmap200a0000)。如果该路径包含rlogin的话，你将需要在执行rlogin的客户端上使用escapeff选项，因为许多rlogin的实作并非是透通的；它们将会从资料流中移除[0xff,0xff,0x73,0x73,跟随的任何 8位元组]这些序列。
诊断 DIAGNOSTICS
讯息使用facilityLOG_DAEMON送到syslog隐形程式。（这个可以藉著以所要的facility定义LOG_PPP巨集来重新编译pppd 加以改变。）为了能够看到错误以及侦错讯息，你将需要编辑你的 /etc/syslog.conf档案来将讯息导向到所希望的设备或档案。
debug选项使得所有送出以及接收的控制封包内容都被记录下来，这是指所有的LCP,PAP,CHAP,或是IPCP封包。如果PPP协商没有成功的话那麽这可能会有用。如果在编译时期开启侦错功能的话，pppd会使用facilityLOG_LOCAL2来取代LOG_DAEMON，而且debug选项会使得额外的侦错讯息被记录下来。
侦错功能也可以藉著传送一个SIGUSR1到pppd程序来启动。侦错功能可以藉著传送一个SIGUSR2到pppd程序来关闭。
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:
- 0
- Pppd has detached, or otherwise the connection was successfully established and terminated at the peer's request.
- 1
- An immediately fatal error of some kind occurred, such as an essential system call failing, or running out of virtual memory.
- 2
- An error was detected in processing the options given, such as two mutually exclusive options being used.
- 3
- Pppd is not setuid-root and the invoking user is not root.
- 4
- The kernel does not support PPP, for example, the PPP kernel driver is not included or cannot be loaded.
- 5
- Pppd terminated because it was sent a SIGINT, SIGTERM or SIGHUP signal.
- 6
- The serial port could not be locked.
- 7
- The serial port could not be opened.
- 8
- The connect script failed (returned a non-zero exit status).
- 9
- The command specified as the argument to thepty option could not be run.
- 10
- The PPP negotiation failed, that is, it didn't reach the point where at least one network protocol (e.g. IP) was running.
- 11
- The peer system failed (or refused) to authenticate itself.
- 12
- The link was established successfully and terminated because it was idle.
- 13
- The link was established successfully and terminated because the connect time limit was reached.
- 14
- Callback was negotiated and an incoming call should arrive shortly.
- 15
- The link was terminated because the peer is not responding to echo requests.
- 16
- The link was terminated by the modem hanging up.
- 17
- The PPP negotiation failed because serial loopback was detected.
- 18
- The init script failed (returned a non-zero exit status).
- 19
- We failed to authenticate ourselves to the peer.
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:
- DEVICE
- The name of the serial tty device being used.
- IFNAME
- The name of the network interface being used.
- IPLOCAL
- The IP address for the local end of the link. This is only set when IPCP has come up.
- IPREMOTE
- The IP address for the remote end of the link. This is only set when IPCP has come up.
- PEERNAME
- The authenticated name of the peer. This is only set if the peer authenticates itself.
- SPEED
- The baud rate of the tty device.
- ORIG_UID
- The real user-id of the user who invoked pppd.
- PPPLOGNAME
- The username of the real user-id that invoked pppd. This is always set. For the ip-down and auth-down scripts, pppd also sets the following variables giving statistics for the connection:
- CONNECT_TIME
- The number of seconds from when the PPP negotiation started until the connection was terminated.
- BYTES_SENT
- The number of bytes sent (at the level of the serial port) during the connection.
- BYTES_RCVD
- The number of bytes received (at the level of the serial port) during the connection.
- LINKNAME
- The logical name of the link, set with thelinkname option. Pppd invokes the following scripts, if they exist. It is not an error if they don't exist.
- /etc/ppp/auth-up
- A program or script which is executed after the remote system successfully authenticates itself. It is executed with the parameters
- interface-name peer-name user-name tty-device speed
- Note that this script is not executed if the peer doesn't authenticate itself, for example when thenoauth option is used.
- /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.
- /etc/ppp/ip-up
- 当线路可以传送以及接收IP封包时（也就是IPCP完成时）执行的一支程式或指令稿。它是以界面的名称、终端设备、速度、本地-IP-位址、远端-IP-位址为参数执行。
- interface-name tty-device speed local-IP-address remote-IP-address ipparam
- /etc/ppp/ip-down
- 当线路不再允许传送以及接收IP封包时执行的一支程式或指令稿。这个指令稿可以用来回复/etc/ppp/ip-up指令稿的影响。它以与ip-up指令稿相同的参数启动。
- /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
- interface-name tty-device speed local-link-local-address remote-link-local-address ipparam
- /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.
- /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
- 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 pppd-pid
- 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 - /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.
文件 FILES
- /var/run/pppn.pid(BSD or Linux), /etc/ppp/pppn.pid (others)
- 在ppp界面单元n上的ppp程序之Process-ID。
- /var/run/ppp-name.pid(BSD or Linux), /etc/ppp/ppp-name.pid (others)
- Process-ID for pppd process for logical linkname (see the linkname option).
- /etc/ppp/pap-secrets
由PAP验证所使用的使用者名称、密码以及IP位址。 This file should be owned by root and not readable or writable by any other user. Pppd will log a warning if this is not the case.- /etc/ppp/chap-secrets
由CHAP验证所使用的名称、暗号以及IP位址。
As for /etc/ppp/pap-secrets, this file should be owned by root and not readable or writable by any other user. Pppd will log a warning if this is not the case.- /etc/ppp/options
pppd的系统预设选项，在使用者预设选项或指令列选项之前读取。- ~/.ppprc
使用者预设选项，在指令列选项之前读取。- /etc/ppp/options.ttyname
所要使用之串列埠的系统预设选项，在指令列之後读取。read after ~/.ppprc. In forming thettyname part of this filename, an initial /dev/ is stripped from the port name (if present), and any slashes in the remaining part are converted to dots.- /etc/ppp/peers
- A directory containing options files which may contain privileged options, even if pppd was invoked by a user other than root. The system administrator can create options files in this directory to permit non-privileged users to dial out without requiring the peer to authenticate, but only to certain trusted peers.
参见 SEE ALSO
- RFC1144
- Jacobson, V.Compressing TCP/IP headers for low-speed serial links. February 1990.
- RFC1321
- Rivest, R.The MD5 Message-Digest Algorithm. April 1992.
- RFC1332
- McGregor, G.PPP Internet Protocol Control Protocol (IPCP). May 1992.
- RFC1334
- Lloyd, B.; Simpson, W.A.PPP authentication protocols. October 1992.
- RFC1661
- Simpson, W.A.The Point-to-Point Protocol (PPP). July 1994.
- RFC1662
- Simpson, W.A.PPP in HDLC-like Framing. July 1994.
- RFC2472
Haskin, D. IP Version 6 over PPP December 1998.
3、CHAT手册：
最近在做pppd程序测试，在修改chat脚本pppd-on-dialer文件时出现了一些小问题，虽然chat脚本似乎并不难懂，但是要精通掌握还是需要花费一点精力的。虽然后来chat脚本问题基本已经解决了，但是为了彻底搞懂chat脚本，在baidu、google能用的关键字都用了结果只有找到一个官方的英文说明，就是没有中文。为了以后参阅花了1个白天3个夜晚的时间将文件翻译成中文。英文水平有限，难免有理解偏差之处，抛砖引玉啦：
CAT中文帮助
名称
chat–调制解调器的自动对话脚本
命令格式
chat [options] script
描述
Chat程序定义了一个计算机和调制解调器之间对话交流，其主要目的是用来在本地PPPD和远端PPPD程序之间建立连接。
选项
-f <chat file>
从chat file文件读取chat脚本。这个选项的使用与chat的脚本参数互斥（mutually exclusive）。 使用者必须具有该文件的读取权限。在文件中允许多线（multiple lines）设定。应该以空格或tab键来分隔字符串。
-l <lock file>
依所指示的锁定文件执行UUCP式的锁定。
如果无法建立该文件那么chat程序将会失败。只有在chat程序因为任何原因而执行失败的情况下该锁定文件才会被删除。 如果该脚本执行成功则锁定文件将会留在磁盘上。当pppd程序不再希望使用串行设备时该锁定文件将会被删除。
不应该同时使用chat以及pppd的锁定选项来使用锁定文件。他们是互斥的选项而且如果你两个都使用将会引起其中一个或者 另一个程序无法获得所需的锁定而失败。
-t <timeout>
对于要接收的预期字符串（expected string）设定的超时限制。如果在该时间限制内没有接收到该字符串的话就不发送回复 字符串（reply string）。可以发送一个变通（alternate）的回复或者如果没有变通的回复字符串则该脚本运行失败。 一个失败的脚本会导致chat程序以一个非零错误代码结束。你也可以使用TIMEOUT字符串来指定超时限制。
-r <report file>
设置报告字符串输出文件。如果你使用REPORT关键字，由此产生的字符串将写入该文件中。 如果没有使用该选项而且你仍使用了REPORT关键字，输出字符串将用标准错误文件记录。
-e
打开echo选项。Echoing使用ECHO关键字在chat脚本的指定位置打开或者关闭。 当echoing被使能，所有调制解调器的输出内容将记录到标准错误文件中。
-E
使能环境变量替换chat脚本中的使用标准的$xxx语法的变量。
-v
要求chat脚本以冗长（verbose）模式执行。 chat程序将记录chat脚本的执行状态，包括所有从调制解调器中接收到的文字以及发送给调制解调器的字符串。 默认记录到SYSLOG去；记录方法可能会通过-S或者-s标志改变。
-V
要求chat脚本使用标准错误的详细模式下执行。 chat程序将记录所有从调制解调器中接收到的文本和发送给调制解调器的字符串到标准错误设备中。 该设备通常是运行chat或pppd程序的本地控制台。
-s
使用标准错误。所有由“-v”产生的日志信息和所有的错误信息将发送到标准错误。
-S
不使用SYSLOG。默认情况下，错误信息被发送到SYSLOG。-S的使用将阻止由’-v’产生的日志信息和错误信息发送到SYSLOG。
-T <phone number>
传递一个任意字符串，通常为一个电话号码，将用于替换发送字符串中的/T替换元字符。
-U <phone number 2>
传递第二个字符串，通常是一个电话号码，将用于替换发送字符串中的/U替换元字符。 当对ISDN终端适配器进行拨号时是非常有用的，它需要两个号码。
script
如果脚本没有以-f选项指定在文件里那么该脚本会如参数般被包含在chat程序里。
CHAT脚本
chat脚本定义通信过程。
一个脚本包含一个或多个“期待对方送出（expect-send）”的配对字符串（pairs of string）， 以空格隔开，还有一个选择性的“期待对方送出的候补（subexpect-subsend）”配对字符串，以短线（dash）隔开。像下面这个例子：
ogin:-BREAK-ogin: ppp ssword: hello2u2
这一行指示chat程序应该期待“ogin:”这个字符串。如果在所分配的时间间隔内接收登录提示失败的话， 那它就送出一个中断程序（break sequence）给远端然后期待“ogin:”这个字符串。 如果第一个“ogin:”被接收到那么中断程序就不会产生。
一旦它接收到该登录提示则chat程序将送出ppp这个字符串然后期待“ssword:”这个提示。 当他接收到到密码提示后，他将会送出密码hello2u2。
一般在回复字符串后面会跟着送出一个回车（carriage return）。 在“期待”字符串里除非以/r字符指令（character sequence）指定为必须否则不会期待它的出现。
期待系列（expect sequence）应该只包含辨识字符串所需要的信息。 因为它一般是存放在磁盘文件里，它不应该包含可变信息。 通常不会以时间字符串（time strings），网络识别字符串（network identification strings），或者其他变化的数据做期待字符串。
为了修正在初始化过程中（initial sequence）可能会传送错误的字符，所以寻找字符串“ogin:”而不是“login:”。 开头的“l”字符可能接收错误而你永远找不到该字符串，即使它已经被系统发送。 同样的原因，脚本寻找“ogin:”而不是“login:”以及“ssword:”而不是“password:”。
一个非常简单的脚本看起来可能像这样：
ogin: ppp ssword: hello2u2
换句话说，期待 …ogin:，发送 ppp，期待 …ssword:，再送出hello2u2。
在实际使用上，简单的脚本是罕见的，至少在原先的字符串没有被接收时应该把候补期待（subexpect sequences）包括进来。 例如，考虑下面这个例子：
ogin:--ogin: ppp ssword: hello2u2
这会是个比前面所用的简单脚本跟好的脚本。它会寻找相同的login:提示，然而， 如果没有接收到的话，会发送出一个单独的返回序列（return sequence）并且再次寻找login:。 如果线路干扰掩盖掉第一个login提示那么接着送出空线路（empty line）经常将会再次产生登录提示。
注释
注释可以嵌入在chat脚本中。注释是一个第一列以“#”字符开头的行。注释行仅仅被chat程序忽略。 如果一个“#”出现在期待指令的第一个字母中，你应该引用该字符串。如果你想等待一个以“#”字符开头的提示符，你必须像这样写：
# 现在等待注销的提示和发送字符串
'# ' logout
从文件中发送数据（SENDING DATA FROM A FILE）
如果发送字符串以“@”符号开头，那么该字符串的其余部分被视为一个文件名称用以获取发送字符串。 如果读取文件的最后一个字符是换行字符，它被删除。该文件可以是一个命名管道（或者FIFO）而不是一个普通文件。 这就提供chat和其他程序通信的一个方法，例如，一个程序提供提示用户和接收用户的密码输入。
ABORT字符串
许多调制解调器以字符串来回报呼叫的状态。这个字符串可能是CONNECTED或者是NO CARRIER或者是BUSY。 通常要是调制解调器连接远端失败的话应该会希望结束脚本。困难的是脚本不会确切地知道它可能接收到那个调制解调器字符串。 在初次尝试时，它可能接收到BUSY然而下次它可能接收到NO CARRIER。
这个“失败”字符串可以用ABORT指令指定到脚本中。像下面这个例子一样写到脚本里：
ABORT BUSY ABORT 'NO CARRIER' '' ATZ OK ATDT5551212 CONNECT
这个指令不会期待什么；而且接着发送ATZ这个字符串。对此期待的回应是OK这个字符串。 当它接收到OK时，字符串ADTD5551212就进行拨号。期待字符串是CONNECT。 如果接收到字串CONNECT那么就会执行脚本其余部分。 然而，要是调制解调器发现电话忙线，他将会发送出BUSY这个字符串。 这会使得该字符串符合失败字符命令(abort character)。 这个脚本将会因为它发现一个失败字符串(abort string)而失败(fail)。 如果他接收到的是NO CARRIER字符串，它也会因为同样的原因而失败。 不是可以接收到字符串就是字符串将终结chat脚本。
CLR_ABORT字符串
这个指令允许清除以前的ABORT字符串设置。ABORT字符串被保存在一个预定大小的数组内（在编译时）； CLR_ABORT将清除条目的空间回收，以便新的字符串可以使用这些空间。
SAY字符串
SAY指令允许脚本在终端上通过标准错误发送字符串给用户。 如果chat正在被pppd运行，而pppd是作为一个守护进程（同它的控制终端分离）运行，标准错误通常被重定向到文件/etc/ppp/connect-errors中。
SAY字符串必须使用单引号或者双引号。如果字符串中需要输出回车和换行，你必须明确地将它们添加到您的字符串。
SAY字符串可以用来提供那些你使用了“ECHO OFF”但是仍想让用户知道发生什么的脚本段落的进度信息。一个例子是：
ABORT BUSY
ECHO OFF
SAY "Dialling your ISP.../n"
'' ATDT5551212
TIMEOUT 120
SAY "Waiting up to 2 minutes for connection ... "
CONNECT ''
SAY "Connected, now logging in ...0
ogin: account
ssword: pass
$ SAY "Logged in OK ...0 etc ...
这段脚本将目前唯一的SAY字符串发送给用户，所有脚本的详细信息将保持隐藏。例如，如果上面这段脚本运行，用户将看到：
Dialling your ISP...
Waiting up to 2 minutes for connection ... Connected, now logging in ...
Logged in OK ...
REPORT字符串
报告字符串类似于ABORT字符串。所不同的是，字符串和所有字符到下一个控制字符如回车，都被写入报告文件。
报告字符串可以用来分离调制解调器的连接字符串中的发送速率和返回该值给chat用户。 报告字符串的分析产生逻辑结合其他字符串过程像寻找期待字符串。 同样的字符串在报告指令和中止指令中的作用可能不是非常有用，但是，他是可能的。
报告字符串并没有改变程序的完成代码。
这些“报告”字符串被脚本中的REPORT指令所指定。方法如以下示例脚本：
REPORT CONNECT ABORT BUSY '' ATDT5551212 CONNECT '' ogin: account
该脚本不期望什么；接着发送字符串ATDT5551212拨打电话期望的字符串是CONNECT。 如果接收到字符串CONNECT脚本的其余部分将被执行。此外程序将字符串“CONNECT”和跟随它之后的任何字符如连接速率写入预期文件。
CLR_REPORT字符串
这个指令允许清除以前的REPORT字符串设置。REPORT字符串被保存在一个预定大小的数组内（在编译时）； CLR_REPORT将清除条目的空间回收，以便新的字符串可以使用这些空间。
ECHO
Echo选项控制是否将调制解调器的输出ECHO到标准错误。该选项可以通过-e选项设置，但它同样可以被ECHO关键字控制。 “期待-发送”对使用ECHO ON使能ECHO，使用ECHO OFF关闭ECHO。使用这个关键字你可以选择哪部分对话应该是可见的。 如下面脚本：
ABORT 'BUSY'
ABORT 'NO CARRIER'
OK/r/n ATD1234567
/r/n /c
ECHO ON
CONNECT /c
ogin: account
所有调制解调器的输出结果、配置和拨号是不可见的，但是从CONNECT（或者BUSY）消息之后所有都被echo。
HANGUP
挂断（HANGUP）选项控制调制解调器挂断是否被视作错误。这个选项对拨号系统脚本是非常有用的，挂断并给你系统回电。 HANGUP选项可以是ON或者OFF。
当HANGUP设置为OFF并且调制解调器挂断（例如，登录一个回电系统的第一阶段之后），chat将继续运行脚本（例如，等待一个来电和第二阶段登录提示）。 只要来电被连接，你应该使用HANGUP ON指令重新安装正常挂断信号行为。这里是一个简单的脚本例子：
ABORT 'BUSY'
OK/r/n ATD1234567
/r/n /c
CONNECT /c
'Callback login:' call_back_ID
HANGUP OFF
ABORT "Bad Login"
'Callback Password:' Call_back_password
TIMEOUT 120
CONNECT /c
HANGUP ON
ABORT "NO CARRIER"
ogin:--BREAK--ogin: real_account
etc ...
TIMEOUT
初始超时值是45秒。这可以用-t参数来修改。你也可以指定“TIMEOUT 0”。
要对下一个期待字符串改变超时值的话，可以使用下面这个例子：
ATZ OK ATDT5551212 CONNECT TIMEOUT 10 ogin:--ogin: TIMEOUT 5 assword: hello2u2
这将会在在期待“login:”提示的时候把超时限制改成10秒。超时限制接着在它寻找密码提示时被改成5秒。
超时限制一旦改变就会持续作用直到它再度被改变。
传送EOT
EOT这个特别的回复字符串指示chat程序应该发送一个EOT字符到远端去。这是一般的文件结束（End-of-file）字符命令。 在EOT后面并不会跟着发送出去一个返回字符（return character）。这个EOT指令可以用^D指令嵌入到发送的字符串里。
产生中断（GENERATING BREAK）
BREAK这个特殊的回复字符串将会使得一个中断情况被送出。这个中断是发送端的一个特殊信号。 接收端一般对此的处理时改变传输率。它可以用来循环测试远端可能的传输率直到你能够接到有效的登录提示。 这个中断命令可以用/K命令嵌入到发送字符串里。
转义指令（ESCAPE SEQUENCES）
期待以及回复字符串可以包含转义指令。所有这种指令在回复字符串中都是合法的。有许多在期待字符串中是合法的。 那些在期待指令中无效的会被指出。
'' 期待或送出一个空字串(null string)。如果你送出一个空字符串那么它还会送出一个返回字符（/r）。 这个指令可以是一对省略符号(apostrophe)或者也可以是引用字符。
/b 代表一个退位(backspace)字符。
/c 抑制在回复字符串结尾的新列(newline)字符。这是送出结尾没有返回字符的字符串的唯一方法。 它必须在发送字符串的结尾。例如，这个指令hello/c将会简单地送出字符h，e，l，l，o。（在期待字符串中无效。）
/d 延迟一秒钟。该程序使用最长延迟为一秒的sleep(1)。（在期待字符串中无效。）
/K 插入一个中断（在期待字串中无效。）
/n 发送一个新列(newline)或换行(linefeed)字元。
/N 送出一个空字符(null character)。同样的指令可以用/0代替。（在期待字符串中无效。）
/p 暂停一小段时间。延迟1/10秒。（在期待字符串中无效。）
/q 抑制字符串写往SYSLOG文件。该??????字串被记录到自己的空间。（在期待字符串中无效。）
/r 传送或期待一个回车字符
/s 代替字符串中的空格。这个可以用在不愿引用包含空格的字符串时。HI TIM和HI/sTIM是相同的。
/t 传送或期待一个定位(tab)字符。
/T 发送-T选项指定的电话号码字符串(在期待中无效)
/U 发送-U选项指定的电话号码字符串2(在期待中无效)
// 传送或期待一个反斜线(backslash)字符。
/ddd 将八进制数字(ddd)转换(collapse)成单一的ASCII字符并将其送出。（某些字符在期待字符串中无效。）
^C 替换含有以C代表之控制字符的指令。例如，字符DC1(17)是以^Q表示。（某些字符在期待字符串中无效。）
环境变量（ENVIRONMENT VARIABLES）
环境变量在chat脚本中是可用的，如果-E选项在命令行被指定。“$”字符用来引用用来替换的环境变量的。 如果替换失败，那是因为要求的环境变量没有设置，变量不被替换。
结束码（TERMINATION CODES）
chat随着下面的结束码终止运行。
0 程序正常终止。这表明脚本没有错误得到正常执行。
1 一个或者多个参数是无效字符串或者期待字符串大于内部缓存。这表明该程序没有正确执行。
2 一个错误发生在程序执行期间。这可能是由于读或写由于某个原因失败或者chat接收到类似SIGINT的信号量。
3 没有被选发送字符串的情况下发生了一个超时事件。这意味着你没有编写正确脚本执行条件或者发生某些突发事件而致期待字符串不能出现。
4 第一个字符串标记为ABORT条件发生。
5 第二个字符串标记为ABORT条件发生。
6 第三个字符串标记为ABORT条件发生。
7 第四个字符串标记为ABORT条件发生。
... 其他结束码也被认为是一个ABORT条件明显字符串。
使用结束码，有可能确定哪些事件终止了脚本。可以决定是否选择字符串“BUSY”而不是“NO DIAL TONE”。 虽然第一个事件可能会重试，第二个事件在重试过程中成功的机会不大。
参阅（SEE ALSO）
关于chat脚本的其他资料可以在UUCP文件里找到。chat脚本的概念由uucico程序所使用的脚本来的。
uucico(1), uucp(1)
版权（COPYRIGHT）
chat程序是个公益程序（public domain）。这并非是GNU public license。如果它毁掉了你可以保留每块碎片。
