PPP

Resources

Wikipedia

PPP (Point-to-Point Protocol) is commonly used in establishing a direct connection between two networking nodes. It can provide connection authentication, transmission encryption, and compression.

Installation

USE flags for net-dialup/ppp Point-to-Point Protocol (PPP)

activefilter	Enables active filter support
atm	Enable Asynchronous Transfer Mode protocol support
gtk	Installs GTK+ password prompting program that can be used by passprompt.so PPP plugin for reading the password from a X11 input terminal
pam	Add support for PAM (Pluggable Authentication Modules) - DANGEROUS to arbitrarily flip
selinux	!!internal use only!! Security Enhanced Linux support, this must be set by the selinux profile or breakage will occur
systemd	Enable use of systemd-specific libraries and features like socket activation or session tracking

Data provided by the Gentoo Package Database · Last update: 2023-10-24 02:47 More information about USE flags

Portage has a USE flag ppp for enabling support for PPP for other packages.

Note
Enabling ppp USE flag will pull in net-dialup/ppp automatically

FILE /etc/portage/make.conf

USE="... ppp ..."

After setting global USE flags update your system to the changes take effect:

root #emerge --ask --changed-use --deep @world

Or emerge net-dialup/ppp package manually:

root #emerge --ask net-dialup/ppp

Kernel

Following kernel options need to be enabled, to support PPPoE, which is used in most cases.

Note
Using PPP compression is not suggested.

KERNEL

Device Drivers  --->
    [*] Network device support  --->
      <*>   PPP (point-to-point protocol) support
      < >     PPP BSD-Compress compression (NEW)
      < >     PPP Deflate compression (NEW)
      [ ]     PPP filtering (NEW)
      < >     PPP MPPE compression (encryption) (EXPERIMENTAL) (NEW)
      [ ]     PPP multilink support (EXPERIMENTAL) (NEW)
      <*>     PPP over Ethernet (EXPERIMENTAL)
      < >     PPP support for async serial ports (NEW)
      < >     PPP support for sync tty ports (NEW)

Optional PPP options

Option	Driver	Description
PPP BSD-Compress compression	ppp_bsdcomp	(Not recommended) Support for data compression. "PPP Deflate compression" is preferable.
PPP filtering	-	Support for packet filtering.
PPP MPPE compression (encryption)	ppp_mppe	Driver for Microsoft Point-to-Point Encryption.
PPP multilink support	-	Support for PPP multilink to combine serveral lines.
PPP over Ethernet	pppoe	Driver for PPPoE.
PPP support for sync tty ports	ppp_sync_tty	Support for synchronous devices.

Finally you need to rebuild linux, install and boot new kernel with PPP support.

Configuration

Provided eth0 following lines should be added for PPPoE connection:

FILE /etc/conf.d/netAdd:

...
config_ppp0="ppp"
link_ppp0="eth0" (Specify your ethernet interface)
plugins_ppp0="pppoe"
username_ppp0='user'
password_ppp0='password'
pppd_ppp0="
noauth
defaultroute
usepeerdns
mtu 9120 (Get the correct MTU (Jumbo frame) value from your eth0 Gigabit Ethernet card interface)
holdoff 3
child-timeout 60
lcp-echo-interval 15
lcp-echo-failure 3
noaccomp noccp nobsdcomp nodeflate nopcomp novj novjccomp"
...
rc_net_ppp0_need="net.eth0"

Create an init script for the PPP device by symlinking to net.lo:

root #ln -s /etc/init.d/net.lo /etc/init.d/net.ppp0

root #/etc/init.d/net.ppp0 start

Example setup with systemd and automatic connection

First, create the configuration file:

FILE /etc/ppp/peers/provider

plugin pppoe.so
# network interface
enp41s0
# login name
name "you_login_to_ISP"
usepeerdns
persist
# Uncomment this to enable dial on demand
#demand
#idle 180
defaultroute
defaultroute-metric 1023
hide-password
noauth
#linkname eth0
ifname eth0

enp41s0 is the network interface card to use. It can be found with ip link command.

Note
When using ppp of version less than 2.4.9, the first line should be (rp- prefix):

plugin rp-pppoe.so

Next, create the password secrets file:

FILE /etc/ppp/chap-secrets

# Secrets for authentication using CHAP
# client        server  secret                  IP addresses
your_login_to_ISP   *       your_secret_password

For this to work at system startup, add the following unit in /etc/systemd/system/pppoe.service:

FILE /etc/systemd/system/pppoe.service

[Unit]
Description=PPPoE connection
BindsTo=sys-subsystem-net-devices-enp41s0.device
After=sys-subsystem-net-devices-enp41s0.device
 
[Service]
Type=forking
PIDFile=/var/run/eth0.pid
#RemainAfterExit=true
ExecStart=/usr/sbin/pon
ExecStop=/usr/sbin/poff provider
 
[Install]
WantedBy=multi-user.target

sys-subsystem-net-devices-enp41s0.device is the network device via which pppoe will connect on. To find out the exact name you can use the following bash command

root #systemctl list-units | grep device | grep net

Optionally, create a service unit to handle wake up after sleep:

FILE /etc/systemd/system/pppoe-after-wakeup.service

[Install]
WantedBy=sleep.target
 
[Unit]
After=systemd-suspend.service systemd-hybrid-sleep.service systemd-hibernate.service
 
[Service]
Type=simple
ExecStart=/bin/systemctl restart pppoe

Finally, test it with:

root #systemctl start pppoe

root #systemctl start pppoe-after-wakeup

If it works as expected, enable them on a permanent basis:

root #systemctl enable pppoe

root #systemctl enable pppoe-after-wakeup

See also

• Gentoo handbook PPPoE configuration