你必须以 root 身份签入来建立这些目录并且编辑这些设立 PPP 连线所需的档案，即使你想让所有的使用者都能使用 PPP．
PPP 使用几个档案来建立并设定 PPP 连结．这些档案在 PPP 2.1.2 与 2.2 中的名称与位置都不同．
在 PPP 2.1.2 中这些档案是:-
/usr/sbin/pppd # PPP 执行档 /usr/sbin/ppp-on # 拨号/连线指令稿 /usr/sbin/ppp-off # 断线指令稿 /etc/ppp/options # 所有连线所使用的选项 /etc/ppp/options.ttyXX # 给某一特定通讯埠使用的选项
在 PPP 2.2 中这些档案是:-
/usr/sbin/pppd # PPP 执行档 /etc/ppp/scripts/ppp-on # 拨号/连线指令稿 /etc/ppp/scripts/ppp-on-dialer # 拨号的 chat 指令稿部份 /etc/ppp/scripts/ppp-off # 断线指令稿 /etc/ppp/options # 所有连线所使用的选项 /etc/ppp/options.ttyXX # 给某一特定通讯埠使用的选项
Red Hat Linux 的使用者应注意标准的 Red Hat 4.X 安装将这些指令稿放在 /usr/doc/ppp-2.2.0f-2/scripts．
在你的 /etc 目录里应该要有个目录:
drwxrwxr-x 2 root root 1024 Oct 9 11:01 ppp
如果它不存在的话 － 以这样的权限建立它．
如果这个目录已经存在，它应该会包含一个称为 options.tpl 的选项档案样板．这个档案包括在下面．
因为它包含所有 PPP 选项的解释所以请你把它印出来（配合 pppd 的线上使用手册来阅读将会是很有用的）．
虽然你可以使用这个档案作为 /etc/ppp/options 档案的基础，但是建立你自己的，没有包含所有在这个样板里的指令的选项档案可能会更好 － 它会短得多而且比较容易阅读／维护．
如果你有多个串列线路／数据机（典型的例子是 PPP 伺服器），那麽建立一个一般化的 /etc/ppp/options 档案，其中包含每个你提供支援拨入的串列埠所使用的共同选项并且为每一个需要个别设定以建立 PPP 连线的串列线路设立个别的选项档案．
这些档案名为 options.ttyx1, options.ttyx2 依此类推（其中 x 是你串列埠的适当代码）．
然而，对於单一 PPP 连线，你可以直接使用 /etc/ppp/options 这个档案．另外一种办法，你可以把所有的选项放进 pppd 指令作为参数．
使用 /etc/ppp/options.ttySx 档案的设定方式会比较容易加以维护．
如果你使用 PPP 来连线到好几个不同的节点去的话，那麽你就可以在 /etc/ppp/options.site 里面为每个节点建立选项档案然後在你连线时指定选项档案作为 PPP 指令的参数．
(使用 file option-file 参数於 pppd 的指令列)．
某些个 PPP 的发行套件似乎漏失了 options.tpl 这个档案，所以在这里有个完整的档案．
我建议你不要直接编辑这个档案来建立你自己的 /etc/ppp/options．
把它拷贝到一个新的档案然後编辑该档案比较好．如果你弄乱了你编辑的档案，你可以回头从原始档案再度开始．
# /etc/ppp/options -*- sh -*- general options for pppd # created 13-Jul-1995 jmk # autodate: 01-Aug-1995 # autotime: 19:45 # Use the executable or shell command specified to set up the serial # line. This script would typically use the "chat" program to dial the # modem and start the remote ppp session. #connect "echo You need to install a connect command." # Run the executable or shell command specified after pppd has # terminated the link. This script could, for example, issue commands # to the modem to cause it to hang up if hardware modem control signals # were not available. #disconnect "chat -- \d+++\d\c OK ath0 OK" # async character map -- 32-bit hex; each bit is a character # that needs to be escaped for pppd to receive it. 0x00000001 # represents '\x01', and 0x80000000 represents '\x1f'. #asyncmap 0 # Require the peer to authenticate itself before allowing network # packets to be sent or received. #auth # Use hardware flow control (i.e. RTS/CTS) to control the flow of data # on the serial port. #crtscts # Use software flow control (i.e. XON/XOFF) to control the flow of data # on the serial port. #xonxoff # Add a default route to the system routing tables, using the peer as # the gateway, when IPCP negotiation is successfully completed. This # entry is removed when the PPP connection is broken. #defaultroute # Specifies that certain characters should be escaped on transmission # (regardless of whether the peer requests them to be escaped with its # async control character map). The characters to be escaped are # specified as a list of hex numbers separated by commas. Note that # almost any character can be specified for the escape option, unlike # the asyncmap option which only allows control characters to be # specified. The characters which may not be escaped are those with hex # values 0x20 - 0x3f or 0x5e. #escape 11,13,ff # Don't use the modem control lines. #local # Specifies that pppd should use a UUCP-style lock on the serial device # to ensure exclusive access to the device. #lock # Use the modem control lines. On Ultrix, this option implies hardware # flow control, as for the crtscts option. (This option is not fully # implemented.) #modem # Set the MRU [Maximum Receive Unit] value to <n> for negotiation. pppd # will ask the peer to send packets of no more than <n> bytes. The # minimum MRU value is 128. The default MRU value is 1500. A value of # 296 is recommended for slow links (40 bytes for TCP/IP header + 256 # bytes of data). #mru 542 # Set the interface netmask to <n>, a 32 bit netmask in "decimal dot" # notation (e.g. 255.255.255.0). #netmask 255.255.255.0 # 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). #noipdefault # Enables the "passive" option in the LCP. With this option, pppd will # attempt to initiate a connection; if no reply is received from the # peer, pppd will then just wait passively for a valid LCP packet from # the peer (instead of exiting, as it does without this option). #passive # With this option, pppd will not transmit LCP packets to initiate a # connection until a valid LCP packet is received from the peer (as for # the "passive" option with old versions of pppd). #silent # Don't request or allow negotiation of any options for LCP and IPCP # (use default values). #-all # Disable Address/Control compression negotiation (use default, i.e. # address/control field disabled). #-ac # Disable asyncmap negotiation (use the default asyncmap, i.e. escape # all control characters). #-am # Don't fork to become a background process (otherwise pppd will do so # if a serial device is specified). #-detach # Disable IP address negotiation (with this option, the remote IP # address must be specified with an option on the command line or in an # options file). #-ip # Disable magic number negotiation. With this option, pppd cannot # detect a looped-back line. #-mn # Disable MRU [Maximum Receive Unit] negotiation (use default, i.e. # 1500). #-mru # Disable protocol field compression negotiation (use default, i.e. # protocol field compression disabled). #-pc # Require the peer to authenticate itself using PAP. # This requires TWO WAY authentication - do NOT use this for a standard # PAP authenticated link to an ISP as this will require the ISP machine # to authenticate itself to your machine (and it will not be able to). #+pap # Don't agree to authenticate using PAP. #-pap # Require the peer to authenticate itself using CHAP [Cryptographic # Handshake Authentication Protocol] authentication. # This requires TWO WAY authentication - do NOT use this for a standard # CHAP authenticated link to an ISP as this will require the ISP machine # to authenticate itself to your machine (and it will not be able to). #+chap # Don't agree to authenticate using CHAP. #-chap # Disable negotiation of Van Jacobson style IP header compression (use # default, i.e. no compression). #-vj # Increase debugging level (same as -d). If this option is given, pppd # 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 appropriately (see syslog.conf(5)). (If # pppd is compiled with extra debugging enabled, it will log messages # using facility local2 instead of daemon). #debug # Append the domain name <d> to the local host name for authentication # purposes. For example, if gethostname() returns the name porsche, # but the fully qualified domain name is porsche.Quotron.COM, you would # use the domain option to set the domain name to Quotron.COM. #domain <d> # Enable debugging code in the kernel-level PPP driver. The argument n # is a number which is the sum of the following values: 1 to enable # general debug messages, 2 to request that the contents of received # packets be printed, and 4 to request that the contents of transmitted # packets be printed. #kdebug n # Set the MTU [Maximum Transmit Unit] value to <n>. Unless the peer # requests a smaller value via MRU negotiation, pppd will request that # the kernel networking code send data packets of no more than n bytes # through the PPP network interface. #mtu <n> # Set the name of the local system for authentication purposes to <n>. # This will probably have to be set to your ISP user name if you are # using PAP/CHAP. #name <n> # Set the user name to use for authenticating this machine with the peer # using PAP to <u>. # Do NOT use this if you are using 'name' above! #user <u> # Enforce the use of the host name as the name of the local system for # authentication purposes (overrides the name option). #usehostname # Set the assumed name of the remote system for authentication purposes # to <n>. #remotename <n> # 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 # Use the system password database for authenticating the peer using # PAP. #login # If this option is given, pppd will send an LCP echo-request frame to # the peer every n seconds. Under 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-echo-interval <n> # If this option is given, pppd will presume the peer to be dead if n # LCP echo-requests are sent without receiving a valid LCP echo-reply. # If this happens, pppd will terminate the connection. Use of this # option requires a non-zero value for the lcp-echo-interval parameter. # This option can be used to enable pppd to terminate after the physical # connection has been broken (e.g., the modem has hung up) in # situations where no hardware modem control lines are available. #lcp-echo-failure <n> # Set the LCP restart interval (retransmission timeout) to <n> seconds # (default 3). #lcp-restart <n> # Set the maximum number of LCP terminate-request transmissions to <n> # (default 3). #lcp-max-terminate <n> # Set the maximum number of LCP configure-request transmissions to <n> # (default 10). # Some PPP servers are slow to start up. You may need to increase this # if you keep getting 'serial line looped back' errors and your are SURE # that you have logged in correctly and PPP should be starting on the server. #lcp-max-configure <n> # Set the maximum number of LCP configure-NAKs returned before starting # to send configure-Rejects instead to <n> (default 10). #lcp-max-failure <n> # Set the IPCP restart interval (retransmission timeout) to <n> # seconds (default 3). #ipcp-restart <n> # Set the maximum number of IPCP terminate-request transmissions to <n> # (default 3). #ipcp-max-terminate <n> # Set the maximum number of IPCP configure-request transmissions to <n> # (default 10). #ipcp-max-configure <n> # Set the maximum number of IPCP configure-NAKs returned before starting # to send configure-Rejects instead to <n> (default 10). #ipcp-max-failure <n> # Set the PAP restart interval (retransmission timeout) to <n> seconds # (default 3). #pap-restart <n> # Set the maximum number of PAP authenticate-request transmissions to # <n> (default 10). #pap-max-authreq <n> # Set the CHAP restart interval (retransmission timeout for # challenges) to <n> seconds (default 3). #chap-restart <n> # Set the maximum number of CHAP challenge transmissions to <n> # (default 10). #chap-max-challenge # If this option is given, pppd will re-challenge the peer every <n> # seconds. #chap-interval <n> # With this option, pppd will accept the peer's idea of our local IP # address, even if the local IP address was specified in an option. #ipcp-accept-local # With this option, pppd will accept the peer's idea of its (remote) IP # address, even if the remote IP address was specified in an option. #ipcp-accept-remote
嗯，完全视情况而定（唉）．这里所提供的应该适用於大部份的伺服器．
然而，如果它无法运作的话，阅读样板档(/etc/ppp/options.tpl) 以及 pppd 的线上使用手册并且告诉你所连线之伺服器的系统管理／使用者支援人员．
你还应该注意这里所展示的连结指令稿也使用了一些给 pppd 的命令列选项以便让事情容易调整些．
# /etc/ppp/options (NO PAP/CHAP) # # 避免 pppd 进入背景执行 -detach # # 使用数据机控制线 modem # 使用 uucp 形态的锁定档以避免它人取用串列装置 lock # 使用硬体流量控制 crtscts # 在递送表格中将此连结建立为预设递送装置 defaultroute # 不使用任何"逸出"控制序列 asyncmap 0 # 最大传送封包大小为 552 bytes mtu 552 # 最大接收封包大小为 552 bytes mru 552 # #-------END OF SAMPLE /etc/ppp/options (no PAP/CHAP)