25.3 使用内核级PPP

25.3.1 设立内核级PPP

　　在开始设置内核级PPP时， 需要确信pppd已经被定位在/usr/sbin 中 且存在/etc/ppp目录。

　　pppd能在两种模式下工作：

1. 作为一个 “客户” ── 您要通过PPP串行线或modem线把您的机器连接到互联网上。

2. 作为“服务器” ──计算机已经位于网络上， 且被用于通过PPP与其它计算机连接。

　　两种情况您都需要设立一个选项文件， (/etc/ppp/options 或者是 ~/.ppprc 如果您的计算机有多个用户使用PPP)。

　　您还需要一些modem/serial软件(comms/kermit就很适合)， 使您能够拨号并与远程主机建立连接。

25.3.2 使用pppd作为客户端

Based on information provided by Trev Roydhouse.

　　下面这个 /etc/ppp/options选项文件能够被用来与CISCO终端服务器的 PPP线连接。

crtscts         # enable hardware flow control
modem           # modem control line
noipdefault     # remote PPP server must supply your IP address
                # if the remote host does not send your IP during IPCP
                # negotiation, remove this option
passive         # wait for LCP packets
domain ppp.foo.com      # put your domain name here

:<remote_ip>    # put the IP of remote PPP host here
                # it will be used to route packets via PPP link
                # if you didn't specified the noipdefault option
                # change this line to <local_ip>:<remote_ip>

defaultroute    # put this if you want that PPP server will be your
                # default router

　　连接：

　　现在您的计算机已经用PPP连接。 如果连接失败， 您可在文件 /etc/ppp/options 中添加 debug 选项， 并查看控制台信息以跟踪问题。

　　下面这个/etc/ppp/pppup脚本能自动完成这三个步骤：

#!/bin/sh
pgrep -l pppd
pid=`pgrep pppd`
if [ "X${pid}" != "X" ] ; then
        echo 'killing pppd, PID=' ${pid}
        kill ${pid}
fi
pgrep -l kermit
pid=`pgrep kermit`
if [ "X${pid}" != "X" ] ; then
        echo 'killing kermit, PID=' ${pid}
        kill -9 ${pid}
fi

ifconfig ppp0 down
ifconfig ppp0 delete

kermit -y /etc/ppp/kermit.dial
pppd /dev/tty01 19200

　　/etc/ppp/kermit.dial 是一个 Kermit 脚本， 它会完成拨号， 并在远程主机上完成所有需要的身份验证过程 (这份文档的最后有一个脚本实例)。

　　使用下面这个脚本/etc/ppp/pppdown断开PPP连线：

#!/bin/sh
pid=`pgrep pppd`
if [ X${pid} != "X" ] ; then
        echo 'killing pppd, PID=' ${pid}
        kill -TERM ${pid}
fi

pgrep -l kermit
pid=`pgrep kermit`
if [ "X${pid}" != "X" ] ; then
        echo 'killing kermit, PID=' ${pid}
        kill -9 ${pid}
fi

/sbin/ifconfig ppp0 down
/sbin/ifconfig ppp0 delete
kermit -y /etc/ppp/kermit.hup
/etc/ppp/ppptest

　　通过执行/usr/etc/ppp/ppptest， 看看pppd 是否仍在运行：

#!/bin/sh
pid=`pgrep pppd`
if [ X${pid} != "X" ] ; then
        echo 'pppd running: PID=' ${pid-NONE}
else
        echo 'No pppd running.'
fi
set -x
netstat -n -I ppp0
ifconfig ppp0

　　执行脚本 /etc/ppp/kermit.hup以挂起moderm， 这个文件包含：

set line /dev/tty01    ; put your modem device here
set speed 19200
set file type binary
set file names literal
set win 8
set rec pack 1024
set send pack 1024
set block 3
set term bytesize 8
set command bytesize 8
set flow none

pau 1
out +++
inp 5 OK
out ATH0\13
echo \13
exit

　　也可以用chat 代替kermit：

　　以下两个文件用以建立pppd连接。

　　/etc/ppp/options：

/dev/cuaa1 115200

crtscts     # enable hardware flow control
modem       # modem control line
connect "/usr/bin/chat -f /etc/ppp/login.chat.script"
noipdefault # remote PPP serve must supply your IP address
            # if the remote host doesn't send your IP during
                # IPCP negotiation, remove this option
passive         # wait for LCP packets
domain <your.domain>  # put your domain name here

:       # put the IP of remote PPP host here
            # it will be used to route packets via PPP link
                # if you didn't specified the noipdefault option
                # change this line to <local_ip>:<remote_ip>

defaultroute    # put this if you want that PPP server will be
            # your default router

　　/etc/ppp/login.chat.script：

ABORT BUSY ABORT 'NO CARRIER' "" AT OK ATDT<phone.number>
  CONNECT "" TIMEOUT 10 ogin:-\\r-ogin: <login-id>
  TIMEOUT 5 sword: <password>

　　一旦这些被安装且修改正确， 您所要做的就是运行pppd， 就像这样：

# pppd

25.3.3 使用pppd作为服务器

　　/etc/ppp/options要包括下面这些内容：

crtscts                         # Hardware flow control
netmask 255.255.255.0           # netmask (not required)
192.114.208.20:192.114.208.165  # IP's of local and remote hosts
                                # local ip must be different from one
                                # you assigned to the Ethernet (or other)
                                # interface on your machine.
                                # remote IP is IP address that will be
                                # assigned to the remote machine
domain ppp.foo.com              # your domain
passive                         # wait for LCP
modem                           # modem line

　　下面这个脚本/etc/ppp/pppserv 使pppd以服务器方式启动：

#!/bin/sh 
pgrep -l pppd
pid=`pgrep pppd`
if [ "X${pid}" != "X" ] ; then
        echo 'killing pppd, PID=' ${pid}
        kill ${pid}
fi
pgrep -l kermit
pid=`pgrep kermit`
if [ "X${pid}" != "X" ] ; then
        echo 'killing kermit, PID=' ${pid}
        kill -9 ${pid}
fi

# reset ppp interface
ifconfig ppp0 down
ifconfig ppp0 delete

# enable autoanswer mode
kermit -y /etc/ppp/kermit.ans

# run ppp
pppd /dev/tty01 19200

　　使用脚本/etc/ppp/pppservdown停止服务器：

#!/bin/sh
pgrep -l pppd
pid=`pgrep pppd`
if [ "X${pid}" != "X" ] ; then
        echo 'killing pppd, PID=' ${pid}
        kill ${pid}
fi
pgrep -l kermit
pid=`pgrep kermit`
if [ "X${pid}" != "X" ] ; then
        echo 'killing kermit, PID=' ${pid}
        kill -9 ${pid}
fi
ifconfig ppp0 down
ifconfig ppp0 delete

kermit -y /etc/ppp/kermit.noans

　　下面的 Kermit 脚本 (/etc/ppp/kermit.ans) 能够启用/禁用您 modem 的自动应答模式。 其内容类似下面这样：

set line /dev/tty01
set speed 19200
set file type binary
set file names literal
set win 8
set rec pack 1024
set send pack 1024
set block 3
set term bytesize 8
set command bytesize 8
set flow none

pau 1
out +++
inp 5 OK
out ATH0\13
inp 5 OK
echo \13
out ATS0=1\13   ; change this to out ATS0=0\13 if you want to disable
                ; autoanswer mode
inp 5 OK
echo \13
exit

　　一个名为/etc/ppp/kermit.dial的脚本用于向远程主机 进行拨号和验证。 您要根据需要定制它。 要加入您的登寻名和密码， 您还要根据 modem 和远程主机的反应修改输入语句。

;
; put the com line attached to the modem here:
;
set line /dev/tty01
;
; put the modem speed here:
;
set speed 19200
set file type binary            ; full 8 bit file xfer
set file names literal
set win 8
set rec pack 1024
set send pack 1024
set block 3
set term bytesize 8
set command bytesize 8
set flow none
set modem hayes
set dial hangup off
set carrier auto                ; Then SET CARRIER if necessary,
set dial display on             ; Then SET DIAL if necessary,
set input echo on
set input timeout proceed
set input case ignore
def \%x 0                       ; login prompt counter
goto slhup

:slcmd                          ; put the modem in command mode
echo Put the modem in command mode.
clear                           ; Clear unread characters from input buffer
pause 1
output +++                      ; hayes escape sequence
input 1 OK\13\10                ; wait for OK
if success goto slhup
output \13
pause 1
output at\13
input 1 OK\13\10
if fail goto slcmd              ; if modem doesn't answer OK, try again

:slhup                          ; hang up the phone
clear                           ; Clear unread characters from input buffer
pause 1
echo Hanging up the phone.
output ath0\13                  ; hayes command for on hook
input 2 OK\13\10
if fail goto slcmd              ; if no OK answer, put modem in command mode

:sldial                         ; dial the number
pause 1
echo Dialing.
output atdt9,550311\13\10               ; put phone number here
assign \%x 0                    ; zero the time counter

:look
clear                           ; Clear unread characters from input buffer
increment \%x                   ; Count the seconds
input 1 {CONNECT }
if success goto sllogin
reinput 1 {NO CARRIER\13\10}
if success goto sldial
reinput 1 {NO DIALTONE\13\10}
if success goto slnodial
reinput 1 {\255}
if success goto slhup
reinput 1 {\127}
if success goto slhup
if < \%x 60 goto look
else goto slhup

:sllogin                        ; login
assign \%x 0                    ; zero the time counter
pause 1
echo Looking for login prompt.

:slloop
increment \%x                   ; Count the seconds
clear                           ; Clear unread characters from input buffer
output \13
;
; put your expected login prompt here:
;
input 1 {Username: }
if success goto sluid
reinput 1 {\255}
if success goto slhup
reinput 1 {\127}
if success goto slhup
if < \%x 10 goto slloop         ; try 10 times to get a login prompt
else goto slhup                 ; hang up and start again if 10 failures

:sluid
;
; put your userid here:
;
output ppp-login\13
input 1 {Password: }
;
; put your password here:
;
output ppp-password\13
input 1 {Entering SLIP mode.}
echo
quit

:slnodial
echo \7No dialtone.  Check the telephone line!\7
exit 1

; local variables:
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; comment-start-skip: "; "
; end: