Reliable way to get external IP address

Question

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Finding the Public IP address in a shell script

I'm currently doing this in a script:

EXTERNAL_IP=`curl -s http://whatismyip.org`

There's got to be a built in linux command or something for this, no?

What is your precise definition of "external IP address"? If you mean the IP address that other sites on the Internet see your web requests as coming from (possibly the address of your HTTP proxy), then you are doing it the right way. If that's not what you mean, then maybe not. — David Schwartz, Nov 30 '11 at 21:44

score 3 · Answer 1 · answered Nov 30 '11 at 21:38

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If you mean your source address as the rest of the Internet sees it, then the way you're doing it now is pretty much it. A machine behind a firewall or other device doing NAT will be happily unaware of any address translation done further along.

You might find that http://ifconfig.me is a bit cleaner for what you're after - have a look under the Command Line Interface section on the front page.

answered Nov 30 '11 at 21:38

Andy Smith

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On EC2 you can also query the metadata: curl http://169.254.169.254/latest/meta-data/public-ipv4 – Josh Nankin Nov 30 '11 at 21:48
Interesting - will remember that one for future reference! – Andy Smith Nov 30 '11 at 22:00

score 1 · Accepted Answer · answered Nov 30 '11 at 21:37

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No, there is no built-in command, and even the command you suggest may not give you what you want if your NAT device is doing anything more complex then a simple masquerading.

answered Nov 30 '11 at 21:37

Zoredache

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Reliable way to get external IP address

2 Answers2