Find network interface by IP address - Linux/Bash

Question

I'm wondering how I can query by IP address using sed, and it will show which interface name that is using it.

For example..

ipconfig -a | grep 10.0.0.10

I would expect it to come back with ETH0

For a start it's ifconfig, ipconfig is a DOS command (I'm guessing that was a typo though). So what is the output of ifconfig -a on its own then? Is there a NIC on your system with an IP of 10.0.0.10 listed? — theruss
– theruss, Commented May 13, 2016 at 1:35
Note on systemd init OS's ipconfig may not be installed, instead the ip command is used (ip addr specifically) — David C. Rankin
– David C. Rankin, Commented May 13, 2016 at 3:34

promaty · Accepted Answer · 2016-07-27 12:58:50Z

6

ifconfig | grep -B1 10.0.0.10 | grep -o "^\w*"

answered Jul 27, 2016 at 12:58

promaty

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2 Comments

Seven Over a year ago

Good solution without awk

Ammar Faizi Over a year ago

Doesn't work with multiple IPs in a single network card.

Henry Ecker · Accepted Answer · 2021-07-22 04:03:56Z

5

ip -br -4 a sh | grep 10.0.0.10 | awk '{print $1}'

edited Jul 22, 2021 at 4:03

Henry Ecker♦

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answered Jul 21, 2021 at 15:11

Hamid Reza Moradi

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Comments

Thanh Nguyen Van · Accepted Answer · 2016-05-13 02:59:15Z

4

You should use this comand :

ifconfig | grep -B1 "inet addr:10.0.0.10" | awk '$1!="inet" && $1!="--" {print $1}'

Hope this help !

answered May 13, 2016 at 2:59

Thanh Nguyen Van

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5 Comments

theruss Over a year ago

I'm not sure how this will help if the OP couldn't find what they were after using plain old grep 10.0.0.10 then adding to the string to find still won't find it.

Thanh Nguyen Van Over a year ago

can you explain more? what is OP , and you'd to print out ethernet_name if it's match with given ip address, right ?

TonyW Over a year ago

OP = original poster, and btw Thanh, this is EXACTLY what I was looking for, thanks :)

tripleee Over a year ago

No, anything with grep x | awk '{ y }' is usually better written awk '/x/ { y }' - this is a useless use of grep

JoshuaTree Over a year ago

Although it appends a newline character to the end though? Why is that?

x-yuri · Accepted Answer · 2024-10-16 07:49:55Z

In iproute2-4.14.0 they added a -json argument:

[ANNOUNCE] iproute2 4.14.1
ip: add new command line argument -json (mutually exclusive with -color)
ip: ipaddress.c: add support for json output

And these days (6.11.0) you can do:

$ ip -json address \
    | jq -r 'map(select(
        (.addr_info | first).local == "192.168.122.5"
    ))[0].ifname'
br-433ed67eb05d

// or

$ ip -json address \
    | jq -r 'map(select(
        .addr_info
        | map(select(.family == "inet" and .local == "192.168.122.5"))
        | length > 0
    ))[0].ifname'
br-433ed67eb05d

// or

$ ip -json address \
    | jq -r 'map(select(
        .addr_info | any(
            .family == "inet" and .local == "192.168.122.5"
        )
    ))[0].ifname'
br-433ed67eb05d

The ip -json address output is of the form:

[
  {
    "ifname": "br-433ed67eb05d",
    "addr_info": [
      {
        "local": "192.168.122.5",
        ...
      }
    ],
    ...
  },
  ...
]

map(f) applies f to the items ({"ifname": ...}) of the input array. select(f) returns its input ({"ifname": ...}) if f is true for that input. (.addr_info | first).local is the local field of the first item in .addr_info. Then [0].ifname makes it return the ifname field of the first result, and -r outputs the string as is, not as a JSON value (in quotes).

Or in a less reliable way (depending on your task you might want to be more careful):

$ ip address | grep -FB2 'inet 192.168.122.5' | head -1 \
    | awk '{print $2}' | sed -E 's/:$//'
br-433ed67eb05d

Another possibly safer option:

$ ip a | grep -E '^([0-9]+: | *inet )' | grep -E -B1 '^ *inet 192.168.122.5' \
    | head -1 | sed -E 's/^[0-9]+: ([^:]+):.*/\1/'
br-433ed67eb05d

The -br[ief] solution was already posted, so I'll just mention that it (-br[ief]) was added in 4.2.0:

[ANNOUNCE] iproute2 4.2.0
add support for brief output for link and addresses

And sh (ip -br -4 a sh) is optional.

RMDS · Accepted Answer · 2016-05-13 07:30:40Z

0

If you want sed specific solution you may try this. Its little hard to digest how it works , but finally this combination works.

 ifconfig | sed -n '/addr:10.0.0.10/{g;H;p};H;x' | awk '{print $1}'

If you want to take it as an argument via script use "$1" or so instead if 10.0.0.10.

Sed manual for reference : http://www.gnu.org/software/sed/manual/sed.html#tail

answered May 13, 2016 at 7:30

RMDS

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