I have Ubuntu server 12.04 installed, so I have no GUI. When I do the command ifconfig, I cannot find my internl ip address. It says inet addr: 127.0.0.1 .

Here is the output of ifconfig -a:

eth0   link encap:Ethernet  HWaddr 00:06:4f:4a:66:f0
    BROADCAST MULTICAST  MTU:1500  Metric:1
    RX packets:0 errors:0 dropped:0 overruns:0 frame:0
    TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
    collisions:0 txqueuelen:1000
    RX bytes:0 (0.0 B)  TX bytes:0 (0.0 B)

eth1   link encap:Ethernet  HWaddr 00:16:ec:05:c8:9c 
    BROADCAST MULTICAST  MTU:1500  Metric:1
    RX packets:0 errors:0 dropped:0 overruns:0 frame:0
    TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
    collisions:0 txqueuelen:1000
    RX bytes:0 (0.0 B)  TX bytes:0 (0.0 B)

lo     Link encap:Local Loopback
    inet addr 127.0.0.1  Mask:255.0.0.0
    inet6 addr:  ::1/128 Scope:Host
    UP LOOPBACK RUNNING MTU:65536  Metric:1
    RX packets:1800 errors:0 dropped:0 overruns:0 frame:0
    Tx packets:1800 errors:0 dropped:0 overruns:0 carrier:0
    collisions:0 txqueuelen:0
    RX bytes:143896 (143.b KB)  TX bytes:143896 (143.8 KB)

here are the contents of etc/network/interfaces:

# The loopback network interface
auto lo
iface lo inet loopback

# The primary network interface
auto eth0
iface eth0 inet dhcp

If someone could edit this for me, the contents of etc/network/interfaces should be on seperate lines.

The output of host askubuntu.com was:

;; connection timed out; no servers could be reached.

I set up owncloud and webmin a few months ago and was using them for a month with no problems. I think the power went off one day 2 months ago and I never turned the server back on until yesterday. I haven't done anything that would have affected the internet setup So i'm not sure why it doesn't work anymore. As far as my network topology goes, I have a pci-e network card for the pc. The ethernet line goes from the network card to a switch, and then to a modem/router from there.

  • 1
    @AvatarParto Those are for interfaces facing public access, this question is about internal networks... – Bruno Pereira Mar 7 '14 at 14:17
  • Out of curiosity, what does /etc/network/interfaces have in it? – Powerlord Mar 7 '14 at 15:54
  • I know how to use the change directory command, but I do not know how to list the files once there, how would I do this? – Cam Jones Mar 7 '14 at 16:05
  • ls will list files in a directory. ls -l will give a detailed listing. To list contents of a particular directory, ls -l /etc/network. To change into a directory and list contents cd /etc/network ;ls -l. To read the contents of etc/network/interfaces (this is a file) sudo pico /etc/network/interfaces. (pico is a lightweight text editor - good for reading & basic editing, and less intimidating than vi.) – douggro Mar 7 '14 at 16:18
up vote 182 down vote accepted

These commands will tell you all network info

ifconfig -a

or

ip addr show

If as you say it only gives you 127.0.0.1 then there are two options:

  1. Your network card is not attached or not recognized by the system

  2. Your network DHCP server is not runnning or not connected

  • when I log in it tells me there are a few upgrades or updates, so I assume it has to talk to official ubuntu website to know it has updates, So i think my internet is working. – Cam Jones Mar 7 '14 at 13:35
  • @Skateguy try to open askubuntu.com and please print all ifconfig -a – kamil Mar 7 '14 at 13:36
  • I have no GUI, i am about to type it out though. – Cam Jones Mar 7 '14 at 13:53
  • 1
    How can I answer the questions that your two options pose? – Cam Jones Mar 7 '14 at 14:58
  • @Skateguy First it seems you don't have a dhcp server and you will have to set your ip manually. can you tell us your network topology, how are you connected to the internet. and please post the output of the following command in your terminal: host askubuntu.com – kamil Mar 7 '14 at 17:01

This is what I currently recommend:

ip route get 8.8.8.8 | awk '{print $NF; exit}'

The advantage of that command is that you don't have to know which interface you are using (eth0? eth1? or maybe wlan0?), you don't have to filter out localhost addresses, or Docker addresses, or VPN tunnels etc. and you will always get the IP address that is currently used for Internet connections at that very moment (important when e.g. you are connected with both ethernet and wifi or via VPN etc.).

This will test not only that you have a correct IP configured on some interface (like with parsing the output of ifconfig) but also that you have the routing table configured to use it correctly.

I found that idea in this answer by Collin Anderson.

I use it in the internalip script in my scripts collection on GitHub, which you can install with:

wget https://rawgit.com/rsp/scripts/master/internalip
chmod a+x internalip

and use as:

internalip

or:

internalip TARGET

and you will get your IP address that would be used to connect with the TARGET IP address. The default target is 8.8.8.8 which is the Google's public DNS resolver and a good default for the Internet.

But if you run it with a different IP:

internalip 127.2.3.4

Then you will get:

127.0.0.1

because that is your IP address that would be used to connect with 127.2.3.4 on the loopback interface. It's useful when your target is on a LAN, VPN or other special network, in which case some other IP could be used for connections than the default IP for reaching the Internet.

External IP

To check your external IP address (the one that the servers on the Internet see when you connect to them - which may be different than the internal IP address described here) see this answer.

  • 1
    this is an awesome answer, thanks! saved me so much headache! :D – user65165 Jul 9 '15 at 17:17
  • This is a useful trick, but the OP was asking about an internal IP, so imay not be not safe to assume that it's routable to 8.8.8.8. – mc0e Nov 27 '15 at 13:52
  • @mc0e Good point. That's why my script takes an optional argument for some other IP - 8.8.8.8 is just the default. In my answer I used 127.2.3.4 as an example. You can use some IP on your intranet or on a VPN as well. The point is that you don't usually have one internal IP address but few different addresses used for different targets. This way you can find the one that is actually used for connections to a given target. – rsp Nov 27 '15 at 15:50
  • 1
    Just so you know, this gives the external IP on Mac. – OZZIE Mar 29 at 12:53
hostname -I

This will give you just ip address without any extra information.

  • 12
    That's perfect. So many overly complicated (but not bad) answers.. this one is just dead simple. – user1003916 Jun 16 '16 at 22:22
  • 2
    Perfect answer..:) – john400 Jul 8 '16 at 4:25
  • 2
    According to man page: ` -I, --all-ip-addresses Display all network addresses of the host. This option enumer‐ ates all configured addresses on all network interfaces. The loopback interface and IPv6 link-local addresses are omitted.` So this will give you ip address on the network you're connected to , but also IP of your machine if you're using it as ethernet or lxd server. In my case it gives two addresses because I have lxd : 192.168.0.78 and 10.0.3.1 – Sergiy Kolodyazhnyy Sep 4 '16 at 18:10
  • 4
    Yep. In my case it's more badly 10.0.2.15 172.18.0.1 172.17.0.1 172.20.0.1 172.21.0.1 172.22.0.1 172.19.0.1 because I'm running some Docker containers ;) – Alex Oct 6 '16 at 16:45
  • 2
    Upvote because other solutions don't work e.g. on raw docker ubuntu image – noonex Feb 5 '17 at 13:21

I think it worth mentioning that running ifconfig along with -a option will display all interfaces wether or not the interface has an IP.

running ifconfig alone, will display only interfaces with IPs assigned.

Here is a nice trick you could use to display only IPs using Perl.

# ifconfig | perl -nle'/dr:(\S+)/ && print $1'
192.168.1.100
127.0.0.1

Your network card is recognized by the system, that why its showing up eth0 and eth1

here is a quick way of assigning IP to your interface, use valid IP/Subnet accordingly.

 ifconfig eth0 192.168.1.200/24 up 

then we need to add a default route

route add default gw 192.168.1.1

Best,

  • 1
    I would try this method but you will have to break it down a little more for me to understand it, as in how to find or know a valid IP, subnet and a valid default route. – Cam Jones Mar 8 '14 at 23:30
  • this is a static IP assignment for your network interface, meaning if you are behind a router with subnet of 192.168.1.0/24 then you can ping an ip ex. 192.168.1.200 and if you get no response, then go a head and use ifconfig interface_name IP_ADDRESS/MASK up Your default gw needs to be added after assigning IP. – user1007727 Mar 12 '14 at 19:17

This command will show all the IP addresses for a single device:

dev=eth0
ip addr show $dev | awk '/inet/ {print $2}' | cut -d/ -f1

It will print one or two lines of output. The first one is the inet/IPv4 address and the other one is inet6/IPv6 if your system is configured to support this.

In case, the ifconfig command didn't display the IP address, there is a very simple and easy way to find out the IP address of the Ubuntu machine through the GUI. Follow the steps below:

Click the network icon in the notification area and click Connection Information. Network icon options

This brings up a window which has a some information, including the IP address. IP address information

There's lots of good answers here to choose from already, but I thought I'd point out facter which is usually, but not necessarily used with puppet for collecting various facts about the system. The main advantage of facter is that it gives nice clean output which saves you all the manipulation with grep, sed, awk, cut, perl, etc. It isn't going to tell you which interface you're interested in, but if you know that, then the following gives you the IP without other cruft to clean up:

facter ipaddress_eth0 

ip command

Here's a variation on ip addr way.

ip has -o option which allows putting all information on single line - this is useful for parsing with tools like awk or perl. In combination with -4 option, we will only see IPv4 addresses. Thus, output would be something like this (note - replace wlan7 with the interface you want to check):

$ ip -4 -o addr show wlan7
3: wlan7    inet 192.168.0.78/24 brd 192.168.0.255 scope global dynamic wlan7\       valid_lft 85654sec preferred_lft 85654sec

As you can see, the IP address is 4th column/word in the output. The rest , is simple parsing exercise via the tool of your choice. Here, I'm using python:

ip -4 -o addr show wlan7 | python -c "import sys;print sys.stdin.readlines()[0].split()[3]" 

Same thing, only with here string <<< and command substitution $()

python -c "import sys;print sys.stdin.readlines()[0].split()[3]"  <<< $(ip -4 -o addr show wlan7)

Personally, I have this saved as a nice function in my ~/.bashrc so less typing is done.

wlan_ip() {
    ip -4 -o addr show wlan7 | python -c "import sys;print sys.stdin.readlines()[0].split()[3]" 
} 

Perl's and Ruby's version are a bit shorter:

$ ip -4 -o addr show  wlan7 | perl -lane 'print $F[3]'                         
192.168.0.78/24

$ ip  -4 -o addr show wlan7 | ruby -n -e 'print $_.split()[3]'                 
192.168.0.78/24

Wireshark

If you're familiar with using network analysis tools, you probably know that to get your ip address, all you need to do is clear the browser cache, start Wireshark capture on the specific interface, and look for http GET packets being transmitted. The destination column will show your ip address

protected by Community Mar 31 '16 at 16:29

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