Get network name linux

How to find network interface name

which is fine, but some machines for some reason use eth1 instead of eth0. I would like to be able to discover the LAN iface name, so I can substitute it in here instead of eth0. Of course, if you can come up with a different oneliner that does the same thing, all good.

display the most active ethernet interface: arp -n -H ether | perl -ne ‘print $1 if /(\S+\n)$/’ | sort | uniq -c | grep -v Iface | sort -n | tail -1 | perl -pe ‘s/.* //’

7 Answers 7

The main NIC will usually have a default route. So:

ip -o -4 route show to default 

ip -o -4 route show to default | awk '' 

ip -o -4 route show to default | awk '' 

Unlike ifconfig, ip has a consistent & parsable output. It only works on Linux; it won’t work on other Unixen.

Not sure if this helps, but it seems that ip route get will show which interface it uses to connect to a remote host.

ubuntu@ip-10-40-24-21:/nail/srv/elasticsearch$ ip route get 8.8.8.8 8.8.8.8 via dev eth0 src

of course you could automate that in shell script with something like,

It seems like on my Ubuntu 15.10 machine this shows the IP address instead of the interface name. @user150471 ‘s answer below works: stackoverflow.com/a/30201105/1069083

Very good! I like this answer because of its versatility in different situations. All one really needs to know is the Ip address of a destination; ip route takes it from there.

Most recenttly systemd/udev has automatically started to assign interface names for all local Ethernet, WLAN and WWAN interfaces to something that we’re all accustomed to . This is a departure from the traditional interface naming scheme («eth0», «eth1», «wlan0», . ) .. now we have to check first what the local interface name is before we can use it while previously we it was a pretty accurate guess that «eth0» was the right name. What you’re asking for is the network NAME .. Here’s a small script to solve the problem

1. Use «ip route get 8.8.8.8 » to figure out which ACTIVE interface has the route to internet ( or currently being used ) Output should look like : 8.8.4.4 via 10.10.1.1 dev enp0s3 src 10.10.1.118 cache
2. Use awk to print the 5th text block for Interface NAME ]# ip route get 8.8.8.8 | awk — » Output : enp0s3
3. Use awk to print the 7th text block for Interface Address ]# ip route get 8.8.8.8 | awk — » Output : 10.10.1.118

Great answer. I find that the ip command outputs two lines («cache and ipid 0x2e6e» on 2nd line). So ip route get 8.8.8.8 | head -n1 | awk — ‘‘ works for me!

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Linux: Get «user-friendly» network interface name

new naming standard assigns name to the interface according to one of the following: Names incorporating Firmware/BIOS provided index numbers for on-board devices (example: eno1) My desired result is a list of IP interface names and the IP address assigned to every interface name, similar to the info showed by but that can be applied on any Linux distribution. for example:

How to get all the IP Interface names and addresses using /proc on Linux?

I know of ls /sys/class/net to get all the available IP interface names, and also cat /proc/net/fib_trie to get all the IP addresses, but how do I match between them?

My desired result is a list of IP interface names and the IP address assigned to every interface name, similar to the info showed by ifconfig but that can be applied on any Linux distribution.

enp4s0f1 5.6.7.1 enp6s0 2.2.2.1 

My desired result is a list of IP interface names and the IP address assigned to every interface name, similar to the info showed by ifconfig but that can be applied on any Linux distribution.

ip addr | grep inet | grep -v "inet6" 

Using the ip system utility. You’re not using /proc/ or /sys/, but it’ll work on any distro with ip on it, which is most of them.

Update: to make it look a bit easier on the eye, use this:

ip addr | grep inet | grep -v "inet6" | awk '' 

How to get Network Interface Card names in Python?, If you are looking to just get a list of the interfaces, use: interface_list = netifaces.interfaces () If you are wanting a specific interface, but don’t know what the number at the end is (ie: eth0), use: interface_list = netifaces.interfaces () interface = filter (lambda x: ‘eth’ in x,interface_list) Share.

Linux: Get «user-friendly» network interface name

I’m writing a program where the user shall select some network interface under Linux like shown here:

Please select a network card: 1) enp2s0 2) wlan3 3) ppp2 

Up to this point I have no problem.

However, I’d like the users to see more «descriptive» names like shown here:

Please select a network card: 1) PCI Ethernet (enp2s0) 2) Wireless LAN (wlan3) 3) Dial-up connection (ppp2) 

• Does Linux know such descriptive names for network interfaces at all?
• If yes: How can I get these names?
• If no: Is there a way to guess the user-friendly name from the interface name with a quite high reliability?
  Example: «ppp*» => «Dial-up connection»; «wl*» => «Wireless network»
  Maybe in combination with the code from /sys/class/net/. /type ?
• If yes: Where can I find a list of possible interface names?

I know that Gnome desktop lists network interface names like «PCI Ethernet» in the network status drop-down menu. So there must be some method to get a «descriptive» name of some network interface.

Does Linux know «friendly» names for network interfaces at all?

If no: Is there a way to guess the user-friendly name from the interface name with a quite high reliability?

You can probably make the generalizations you have suggested. If you are on a systemd based systems, take a look at the systemd net naming scheme, which shows the prefixes used for different interface types:

+--------+------------------------------------+ | Prefix | Description | +--------+------------------------------------+ | en | Ethernet | | ib | InfiniBand | | sl | serial line IP (slip) | | wl | Wireless local area network (WLAN) | | ww | Wireless wide area network (WWAN | +--------+------------------------------------+ 

Maybe in combination with the code from /sys/class/net/. /type?

I’m not sure that type information is going to be helpful. E.g., both ethernet and wireless interfaces show type of 1 . On the other hand, you can positively identify ppp interfaces, for example, using this value.

The possible values for type are available in if_arp.h .

these are native naming policies systemd uses. with the old naming (eth0,wlan0. ) an interface name was not predictable (for example, your first eth card could get a name other than eth0) and this caused all sorts of problems. new naming standard assigns name to the interface according to one of the following:

1. Names incorporating Firmware/BIOS provided index numbers for on-board devices (example: eno1)
2. Names incorporating Firmware/BIOS provided PCI Express hotplug slot index numbers (example: ens1)
3. Names incorporating physical/geographical location of the connector of the hardware (example: enp2s0)
4. Names incorporating the interfaces’s MAC address (example: enx78e7d1ea46da)
5. Classic, unpredictable kernel-native ethX naming (example: eth0)

systemd will start by 1, falling back to 2,3.

I should add, if you read the link which I posted, you can use your own names!

You create your own manual naming scheme, for example by naming your interfaces «internet0», «dmz0» or «lan0». For that create your own .link files in /etc/systemd/network/, that choose an explicit name or a better naming scheme for one, some, or all of your interfaces. See systemd.link(5) for more information.

Get the network interface type in Linux via C program, Here is what i understood that eth0 is interface name. While there can be several network interfaces (eth0, eth1, eth2) and several virtual interfaces (tap0, tap1, etc) and wireless ones, all of them are Ethernet interfaces. The same for loopbacks, being lo as interface name, its interface is Local Loopback.

Retrieve the name of a Network Interface using an IP Address and AWK Bash

I am trying to use Bash on CentOS 6.4 to retrieve the network interface name attached to an IP address using AWK. I have a bit of command from a Solaris box, but I’m not sure how to convert it to Linux output.

The command looks like this:

ifconfig -a | awk ' $1 ~ /:/ $2 == "'$1'" < print lastif ; exit; >' 

Its part of a script, so it takes commandline argument like monitor.sh x.x.x.x y.y.y.y and it uses the first x.x.x.x to get the interface name, then makes $1 == $2 so then it can ping y.y.y.y later. I’m guessing that in Solaris the ifconfig -a output is different than CentOS. I can get the interface name if the IP and interface are on the same line, but in linux, they’re on two different lines. Any ideas.

I don’t have CentOS, but in RHEL, IP address is listed as inet address. I believe they should be same.

The following command should give you the interface name which has a IP address.

export iface=$(ifconfig | grep -B1 "inet addr:x.x.x.x" | awk '$1!="inet" && $1!="--" ') echo "$iface" # To get the interface name for x.x.x.x ip 

And this one should show the IP including localhost :

ifconfig | grep "inet addr:" | sed -e 's/addr:/addr: /g' | awk '' 

geting ifname for 127.0.0.1 (or any other IP)

ifconfig | awk '/127.0.0.1/ ' RS="\n\n" lo 

ifconfig | awk -F"[ :]+" '/inet addr:/ ' 

Post the output of ifconfig, and I can help you fine tune for your OS

Bash script to retrieve name of Ethernet Network interface, In Ubuntu 16.04 I made a script to dinamically configure IP address of the wired ethernet interface based on certain parameters. Now the problem is that in my script I assume that the name is eth0, but this is not always true.. assuming that I have only one wired network interface (not necessary plugged) …

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Linux getting all network interface names

I need to collect all the interface names, even the ones that aren’t up at the moment. Like ifconfig -a . getifaddrs() is iterating through same interface name multiple times. How can I collect all the interface names just once using getifaddrs() ?

7 Answers 7

You could check which entries from getifaddrs belong to the AF_PACKET family. On my system that seems to list all interfaces:

struct ifaddrs *addrs,*tmp; getifaddrs(&addrs); tmp = addrs; while (tmp) < if (tmp->ifa_addr && tmp->ifa_addr->sa_family == AF_PACKET) printf("%s\n", tmp->ifa_name); tmp = tmp->ifa_next; > freeifaddrs(addrs); 

getifaddrs() will only return your interfaces addresses, not the interfaces themselves.

What if any of your interface has no address, or no address of the requested family, as suggested with the ‘AF_PACKET’ one ?

Here, an example where I’ve got a tunnel interface (with an OpenVPN connexion), and where I’m listing all entries from getifaddrs() for each of my network interfaces:

[0] 1: lo address family: 17 (AF_PACKET) b4:11:00:00:00:01 address family: 2 (AF_INET) address: address family: 10 (AF_INET6) address: [. ] [5] 10: tun0 address family: 2 (AF_INET) address: [EOF] 

Bam. No AF_PACKET on the «tun0» interface, but it DOES exist on the system.

You should, instead, use if_nameindex() syscall, which does exactly what you want. In other words, with no arguments, it returns a list of all interfaces on your system:

#include #include int main (void) < struct if_nameindex *if_nidxs, *intf; if_nidxs = if_nameindex(); if ( if_nidxs != NULL ) < for (intf = if_nidxs; intf->if_index != 0 || intf->if_name != NULL; intf++) < printf("%s\n", intf->if_name); > if_freenameindex(if_nidxs); > return 0; > 

Your example code is leaking the memory. According to the documentation (if_nameindex) if_nameindex() function dynamically allocates memory that later should be freed by calling if_freenameindex().

Hello void main (void) is improper. You should use int main() or int main(void) Also main should return a value.

It seems that ifconfig -a only lists active interfaces (at least on Fedora 19). I know I have at least one more network card that I’m not seeing. Anyway, I get the same list as:

Which could easily be done programatically.

I thing this show you all interface, at least for me

You are on the right track (it is getifaddrs). It returns each interface once per family, so you get eth0 for ipv4 and one for ipv6. If you just want each interface once you will have to uniq the output yourself.

I need the main device that is being used by the system (assuming there is only one) such as eth0 wlan0 or whatever RHEL7 is trying to do.

The best I hacked together was this:

#!/bin/bash # -- Get me the interface for the main ip on system for each in $(ls -1 /sys/class/net) ;do result=$(ip addr show $each | awk '$1 == "inet" ' | grep "$(hostname -I | cut -d' ' -f1)") if [ ! -z "$" ] && [ -d /sys/class/net/$ ] ;then echo "Device: $each IP: $result" break; fi done 

 ./maineth.sh Device: enp0s25 IP: 192.168.1.6 

Use this one. I added the appropriate comments for ease of understanding.

void extract_network_interface_names() < /* DEFINITION * #include * struct if_nameindex * if_nameindex() : function that returns a pointer. * The if_nameindex() function returns an array of if_nameindex structs. There is one struct for each network interface * The if_nameindex struct contains at least the following members: * unsigned int if_index : which is the index of each network interface * char * if_name : which is the name of the interface=the C style string= an array of characters terminated in the NULL character \0 * * The end of the array of struct is indicated by an entry with if_index=0 && if_name=NULL * The if_nameindex() function returns an array of structs if successful, or NULL if some error occurred or not enough memory is available */ puts("Extracting network interface names. "); puts("Listing all available network interface names on this machine. "); puts("********************************"); int counter_network_interfaces=0; struct if_nameindex * interface_indexes; struct if_nameindex * interface; interface_indexes=if_nameindex(); if(interface_indexes==NULL) //Some error occurred during the execution of if_nameindex() function or there is no enough memory available < perror("If_nameindex"); printf("Ooops. error while extracting the network interface names.\n"); exit(EXIT_FAILURE); >//Loop through the elements of the array of if_nameindex structs for(interface=interface_indexes;interface->if_index!=0 && interface->if_name!=NULL;interface++) < counter_network_interfaces++; printf("There exists a network interface called \"%s\" with index %d. \n",interface->if_name, interface->if_index); > puts("*******************************"); printf("In total, there is a number of %d network interfaces on this machine.\n",counter_network_interfaces); > 

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