plipconfig

plipconfig [-dhV] [-a] [interface [up|down] [hwaddr ADDR] [mtu MTU] [irq IRQ]]

-a, --all
    Display or configure all PLIP interfaces (requires superuser).

-d, --debug
    Enable verbose debugging output.

-h, --help
    Show usage help and exit.

-V, --version
    Print version information and exit.

interface
    PLIP device name, e.g., plip0 for /dev/lp0.

up
    Bring the interface online.

down
    Shut down the interface.

hwaddr ADDR
    Set hardware (MAC) address, format XX:XX:XX:XX:XX:XX.

mtu MTU
    Set maximum transmission unit (default 1500; lower for reliability).

irq IRQ
    Set interrupt request line (0 for auto-detect).

plipconfig is a Linux utility for configuring PLIP (Parallel Line Internet Protocol) interfaces, enabling point-to-point networking over parallel (LPT) ports using a null-modem cable. Developed for early Linux systems lacking Ethernet, PLIP allows direct IP communication between two machines at speeds up to ~200 kbps, ideal for file transfers or legacy setups.

Usage involves loading the plip kernel module (modprobe plip), associating it with a parallel port (e.g., /dev/lp0 for plip0), then using plipconfig to activate the interface, set parameters like IRQ, MTU, and hardware address. Pair with ifconfig to assign IP addresses, e.g., ifconfig plip0 192.168.1.1 pointopoint 192.168.1.2.

Key steps: Connect null-modem cable (DB-25 or compatible), ensure no printer conflicts, probe IRQ if needed. Display status with plipconfig plip0. Though functional, PLIP is obsolete due to slow speeds and rare parallel ports; prefer USB-Ethernet adapters or Wi-Fi.

Part of the net-tools suite, it's still available in many distros but deprecated in favor of iproute2.

Obsolete technology; parallel ports scarce on modern hardware. IRQ/printer conflicts common. Low speeds (~100-200kbps). Requires matching setup on peer machine. Not supported in all kernels.

Load with modprobe plip; bind to port via plipconfig plip0 irq N unit 0 (unit 0=/dev/lp0).

DB-25 null-modem cable (parallel ports); ensure twisted pairs for reliability.

Use ip link with USB adapters or crossover Ethernet cables.

Introduced in early 1990s Linux kernels (v1.x) as part of net-tools for parallel port networking. Peaked in pre-Ethernet era; declined with USB/Ethernet rise. Maintained in net-tools until iproute2 supplanted it (~2001+).

plip(4), ifconfig(8), ip(8), route(8), modprobe(8)