Installing and Administering PPP

30 Chapter 2

Setting Up PPP Connections

Increasing the Number of IP Tunnels

pppd uses IP tunnels to pass packets between the serial port and IP

layer. During bootup, /sbin/init.d/ppp creates 16 IP tunnels (the

default value is deﬁned in /etc/ppp/tunconf) which will support 16

concurrent pppd processes. Each IP tunnel creates three device ﬁles.

Each pppd process facilitates a PPP connection. The kernel can support

a maximum of 64 IP tunnels. If you need more than 16 IP tunnels, you

can increase the value of NTUN in /etc/ppp/tunconf and reboot the

system.

See tun(4) for more details about conﬁguring IP tunnels.