/usr/share/doc/ppp/examples/scripts/ppp-on-ssh is in ppp 2.4.5-5ubuntu1.
This file is owned by root:root, with mode 0o755.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 | #!/bin/sh
#
# A sample script to establish PPP session(s) via SSH 1.x
#
# Adi Masputra <adi.masputra@sun.com>
# Jan 24, 2000
#
#
# You'd definitely want to change the following addresses to suit
# your network configuration
#
LOC_IP=10.0.0.1
REM_IP=10.0.0.2
NETMASK=255.255.0.0
export LOC_IP REM_IP
#
# This is the remote peer where sshd is running, either
# its hostname or IP address
#
PPPD_RHOST=myremotehost
#
# For this example, we assume that pppd on both local and remote
# machines reside in the same place, /usr/local/bin/pppd
#
PPPD_LOC=/usr/local/bin/pppd
#
# The location of local options file (where ssh client is running).
# Note that the sample options file included in the distribution
# may need further customizations, depending on your needs. The 'noauth'
# option specified in the file is there to simplify the example, although
# some may choose to have it there and rely on ssh authentication
# instead.
#
PPPD_LOC_OPT=/etc/ppp/options-ssh-loc
#
# The location of remote options file (where sshd daemon is running)
# Note that the sample options file included in the distribution
# may need further customizations, depending on your needs. The 'noauth'
# option specified in the file is there to simplify the example, although
# some may choose to have it there and rely on ssh authentication
# instead. Also note that the remote options file need to include the 'notty'
# options for this to work.
#
PPPD_REM_OPT=/etc/ppp/options-ssh-rem
#
# The location of ssh client on the local machine
#
SSH_LOC=/usr/local/bin/ssh
export PPPD_LOC PPPD_LOC_OPT PPPD_REM_OPT PPPD_RHOST SSH_LOC
#
# Uncomment the following to enable IPv6, note that the IPv6 support
# needs to be enabled during compilation
#
# PPPD_IPV6='+ipv6 ipv6cp-use-ipaddr'
export PPPD_IPV6
#
# And execute pppd with the pty option, specifying ssh client as the
# slave side of the pseudo-tty master/slave pair. Note that on this example,
# ssh has been compiled to allow NULL encryption (thus the '-c none' option),
# but in reality, you'd probably want to specify the encryption algorithm.
# See the man page of ssh(1) for details.
#
exec $PPPD_LOC \
pty '$SSH_LOC -c none $PPPD_RHOST $PPPD_LOC $REM_IP:$LOC_IP $PPPD_IPV6 file $PPPD_REM_OPT' \
$LOC_IP:$REM_IP netmask $NETMASK $PPPD_IPV6 file $PPPD_LOC_OPT
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