Introduction to Networking Tools

lspci is a command on Unix-like operating systems that prints ("lists") detailed information about all PCI buses and devices in the system.

Example usage

Example output on a Linux system:

# lspci

00:00.0 Host bridge: Intel Corporation 82815 815 Chipset Host Bridge and Memory Controller Hub (rev 11)

00:02.0 VGA compatible controller: Intel Corporation 82815 Chipset Graphics Controller (CGC) (rev 11)

00:1e.0 PCI bridge: Intel Corporation 82801 Mobile PCI Bridge (rev 03)

00:1f.0 ISA bridge: Intel Corporation 82801BAM ISA Bridge (LPC) (rev 03)

00:1f.1 IDE interface: Intel Corporation 82801BAM IDE U100 Controller (rev 03)

00:1f.2 USB Controller: Intel Corporation 82801BA/BAM USB Controller #1 (rev 03)

00:1f.3 SMBus: Intel Corporation 82801BA/BAM SMBus Controller (rev 03)

00:1f.4 USB Controller: Intel Corporation 82801BA/BAM USB Controller #2 (rev 03)

00:1f.5 Multimedia audio controller: Intel Corporation 82801BA/BAM AC'97 Audio Controller (rev 03)

01:03.0 CardBus bridge: O2 Micro, Inc. OZ6933/711E1 CardBus/SmartCardBus Controller (rev 01)

01:03.1 CardBus bridge: O2 Micro, Inc. OZ6933/711E1 CardBus/SmartCardBus Controller (rev 01)

01:0b.0 PCI bridge: Actiontec Electronics Inc Mini-PCI bridge (rev 11)

02:04.0 Ethernet controller: Intel Corporation 82557/8/9/0/1 Ethernet Pro 100 (rev 08)

02:08.0 Communication controller: Agere Systems WinModem 56k (rev 01)

If many devices are shown as unknown (e.g. "Unknown device 2830 (rev 02)), issuing the command 'update-pciids' will usually correct this.

lsusb is a similar command for USB buses and devices.

hwinfo is for all the hardware.

·         dmesg — prints the message buffer of the kernel.

·         uname — prints the name, version and other details about the current machine and the operating system

·         dmidecode — prints information from DMI interface from BIOS.

·         lscpu — prints information about your CPU(s).

Ethtool utility is used to view and change the ethernet device parameters.

When you execute ethtool command with a device name, it displays the following information about the ethernet device.

# ethtool eth0

Settings for eth0:

        Supported ports: [ TP ]

        Supported link modes:   10baseT/Half 10baseT/Full

                                100baseT/Half 100baseT/Full

                                1000baseT/Full

        Supports auto-negotiation: Yes

        Advertised link modes:  10baseT/Half 10baseT/Full

                                100baseT/Half 100baseT/Full

                                1000baseT/Full

        Advertised auto-negotiation: Yes

        Speed: 100Mb/s

        Duplex: Full

        Port: Twisted Pair

        PHYAD: 1

        Transceiver: internal

        Auto-negotiation: on

This above ethtool output displays ethernet card properties such as speed, wake on, duplex and the link detection status. Following are the three types of duplexes available.

§  Full duplex : Enables sending and receiving of packets at the same time. This mode is used when the ethernet device is connected to a switch.

§  Half duplex : Enables either sending or receiving of packets at a single point of time. This mode is used when the ethernet device is connected to a hub.

§  Auto-negotiation : If enabled, the ethernet device itself decides whether to use either full duplex or half duplex based on the network the ethernet device attached to.

lsof meaning ‘LiSt Open Files’ is used to find out which files are open by which process. As we all know Linux/Unix considers everything as a files (pipes, sockets, directories, devices etc). One of the reason to use lsof command is when a disk cannot be unmounted as it says the files are being used. With the help of this command we can easily identify the files which are in use.

In the below example, it will show long listing of open files some of them are extracted for better understanding which displays the columns like Command, PID, USER, FD, TYPE etc.

# lsof

COMMAND    PID      USER   FD      TYPE     DEVICE  SIZE/OFF       NODE NAME

init         1      root  cwd      DIR      253,0      4096          2 /

init         1      root  rtd      DIR      253,0      4096          2 /

init         1      root  txt      REG      253,0    145180     147164 /sbin/init

init         1      root  mem      REG      253,0   1889704     190149 /lib/libc-2.12.so

init         1      root   0u      CHR        1,3       0t0       3764 /dev/null

init         1      root   1u      CHR        1,3       0t0       3764 /dev/null

init         1      root   2u      CHR        1,3       0t0       3764 /dev/null

init         1      root   3r     FIFO        0,8       0t0       8449 pipe

init         1      root   4w     FIFO       0,8       0t0       8449 pipe

init         1      root   5r      DIR       0,10         0          1 inotify

init         1      root   6r      DIR       0,10         0          1 inotify

init         1      root   7u     unix 0xc1513880       0t0       8450 socket

Sections and it’s values are self-explanatory. However, we’ll review FD & TYPE columns more precisely.

FD – stands for File descriptor and may seen some of the values as:

 1.   cwd current working directory

2.   rtd root directory

3.   txt program text (code and data)

4.   mem memory-mapped file

Also in FD column numbers like 1u is actual file descriptor and followed by u,r,w of it’s mode as:

§  r for read access.

§  w for write access.

§  u for read and write access.

TYPE – of files and it’s identification.

§  DIR – Directory

§  REG – Regular file

§  CHR – Character special file.

§  FIFO – First In First Out