Serial Baris IP dan Paralel Baris IP:

Linux dapat mendukung protokol IP melalui antarmuka perangkat serial. Jarak jauh ini biasanya didukung menggunakan modem melalui saluran telepon (POTS: Plain Old Telephone Service) atau komunikasi satelit.
SLIP: Serial Line IP (older than PPP and less capable)
Devices:

Interfaces				Description
sl0	sl1	sl2	sl3	SLIP interfaces. Linux kernel supports up to four.
COM1	COM2	COM3	COM4	Serial Ports (RS-232 hardware)
/dev/ttyS0	/dev/ttyS1	/dev/ttyS2	/dev/ttyS3	Serial devices (dial in) (virtual terminal consoles)
/dev/cua0	/dev/cua1	/dev/cua2	/dev/cua3	Serial devices (dial out)
4	4	4	4	Interface major numbers (dial in)
5	5	5	5	Interface major numbers (dial out)
64	65	66	67	Interface minor numbers

The command ls -l /dev/ttyS* /dev/cua* will show the device major and minor numbers. The major and minor numbers are used when creating a SPLIP interface: Example:

• mknod -m 666 /dev/cua1 c 5 65
• chown root.uucp /dev/cua1

SLIP configuration:

• Configure /etc/resolve.conf
  (See notes above in this tutorial)
• Attach network interface to serial line on COM2: /sbin/slattach -p slip -s 19200 /dev/ttyS1 &
• Assign local and remote IP: /sbin/ifconfig sl0 192.168.1.10 pointopoint 192.168.1.40 up
  Assign local IP (192.168.1.10) and connect to remote server (192.168.1.40)
  Alternate example: /sbin/route add plip1 192.168.1.10 pointopoint 192.168.1.40
• Add route: /sbin/route add default dev sl0 &

PLIP: Parallel Line IP 
Point to point link serial (bukan siaran jaringan garis ethernet), dapat alsobe didukung melalui port printer paralel.
Sebuah jaringan IP pada 10 sampai 20 kbps lebih port printer paralel atau lp0 LP1 jauh lebih cepat dari serial. Linux mendukung modus 0 byte PLIP setengah mentransfer data pada suatu waktu. Membutuhkan "Printer NULL" atau "Turbo Laplink" koneksi printer. Lihat driver kernel / net / Space.c.

Interface	I/O Port	IRQ
plip0	0x3BC	7
plip1	0x378	7
plip2	0x278	5

PLIP Configuration:

• ifconfig plip1 192.168.1.10 pointopoint 192.168.1.40
  connect host 192.168.1.10 to remote host 192.168.1.40
• route add default gw 192.168.1.40
  Specify remote host as the gateway.

On the remote host at the other end of the cable, the opposite must be specified:

• ifconfig plip1 192.168.1.40 pointopoint 192.168.1.10
• route add 192.168.1.10 gw 192.168.1.40

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Serial port related man pages:

• setserial - get/set Linux serial port information
  Typical configuration:
  • Interrupt detection: /sbin/setserial -W /dev/cua*
  • Configuration: /sbin/setserial /dev/cua1 auto_irq skip_test autoconfig
    or /sbin/setserial /dev/cua1 auto_irq skip_test autoconfig uart 16550
  • Display Configuration: /sbin/setserial -bg /dev/cua*
  • Enable hardware handshake: stty crtscts < /dev/cua1
    (verify: stty -s < /dev/cua1)

stty - perubahan dan pengaturan terminal cetak baris
tty - mencetak nama file dari terminal terhubung ke input standar
pppd - Point-to-Point Protocol Daemon
slattach - melampirkan antarmuka jaringan ke serial line
mknod - membuat file blok atau karakter khusus