curl: (6) Couldn't resolve host 'ifconfig'

From a Linux box, I can run;

# curl ifconfig

which typically returns my public IP.

However, now and then, there is an error;

curl: (6) Couldn't resolve host 'ifconfig'

I know the DNS server is up and running so why does this work and why does it not work at times?
projectsAsked:
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gheistCommented:
It never worked.
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StampelCommented:
That should work :

# curl ifconfig.me
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Gerwin Jansen, EE MVETopic Advisor Commented:
Try this:

curl echoip.com
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projectsAuthor Commented:
@gheist;
>It never worked.

Sorry, that was a typo and meant to be; curl ifconfig.me

@Stampel;
>That should work :
># curl ifconfig.me

Yes, it does but my question is wanting to understand what would cause it not to work sometimes. It seems to be a dns timeout yet it's not because I tested a dns request at the same time I tested this and dns worked fine.

@Gerwin Jansen;
>Try this:
>curl echoip.com

I guess my code should use more than one service, randomly.

The line is;

MYIP=$(curl ifconfig.me)

I guess I need a little logic here so that if one service times out, use the next to get the IP into $MYIP. However, I would prefer using say two or three services, and randomly.

If someone could give me the necessary code, that would solve my question.
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Gerwin Jansen, EE MVETopic Advisor Commented:
The ifconfig.me site is not accessible for me, don't know why, echoip.com is accessible and is working. So why ifconfig.me is not working all the time for you I don't know just that echoip.com is - I'd use echoip.com
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gheistCommented:
Maybe you hist rate limit of site because of such heavy usage...
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projectsAuthor Commented:
I don't think it's a limit problem because it works now and then, randomly and with various servers. I don't hit them very often, maybe once a day with 5 servers.

Either way, the solution would be a little code to allow for randomly switching between providers so that none ever hit a limit, are overused, etc.
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StampelCommented:
Your subject was
"curl: (6) Couldn't resolve host 'ifconfig'"

This is the response you would get when asking to shell
"[root@xxx ~]# curl ifconfig
=> curl: (6) Couldn't resolve host 'ifconfig'

When you are running curl ifconfig.me you would not get the error
[root@xxx ~]# curl ifconfig.me
=> 215.1.2.3

If you get other errors you can tcpdump to see what curl tries to hit.
Probably the host is not available at this time or a dns problem at this time thats all.
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StampelCommented:
For the curiosity i checked with tcpdump ...
curl ifconfig.me is connectoing to host www1266uf.sakura.ne.jp and port http

check http://www1266uf.sakura.ne.jp/
:)
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Gerwin Jansen, EE MVETopic Advisor Commented:
Just ping ifconfig.me and you would have seen the same šŸ˜
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StampelCommented:
would not give you the host curl is looking for and neither your IP address neither the port curl is querying (http)
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projectsAuthor Commented:
I am not sure what we are all talking about anymore at this point.

Yes, 'curl ifconfig.me' is what my code uses but sometimes it times out which is why I'd like to use a random source in the code itself. The 'curl ifconfig' was a typo.
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Gerwin Jansen, EE MVETopic Advisor Commented:
You could just change your code to 'curl echoip.com' or 'curl ip.appspot.com' or 'curl  icanhazip.com', how does your code look like where the curl command is implemented? We can create some 'random' select I suppose, what shell are you using?
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Gerwin Jansen, EE MVETopic Advisor Commented:
Quick bash example:

number=$(echo $RANDOM % 4 + 1 | bc)
case $number in
  1 )
    ip=$(curl 2>/dev/null echoip.com) ;;
  2 )
    ip=$(curl 2>/dev/null ip.appspot.com) ;;
  3 )
    ip=$(curl 2>/dev/null icanhazip.com) ;;
  4 )
    ip=$(curl 2>/dev/null ifconfig.me) ;;
esac
echo "IP address is: $ip"

Open in new window

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projectsAuthor Commented:
Linux, bash script.
Yes, I could just use another service but I'd rather have something a little better.
Perhaps a timeout so that if one service doesn't respond, move to the next and always random.

All I'm looking for is to stick the public IP only into MYIP.

My current line reads;

MYIP=$(curl ifconfig.me)

This particular device doesn't have 'bc' on it.
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Gerwin Jansen, EE MVETopic Advisor Commented:
Add --max-time <seconds> to the curl command(s) - random + timeout doesn't make much sense to me.

Just put 3 or 4 of them in sequence, quit when one has returned IP address:
ip=""
for site in echoip.com ip.appspot.com icanhazip.com ifconfig.me
do
  ip=$(curl -f --max-time 2 2>/dev/null ${site})
  if [ "${ip}" = "" ]; then
    continue
  else
    break
  fi 
done;

if [ "${ip}" = "" ]; then
  echo "IP not found"
else
  echo "Site used: ${site}"
  echo "IP address is: ${ip}"
fi

Open in new window

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projectsAuthor Commented:
Does the trick, thank you.
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projectsAuthor Commented:
That code is fine but I'm surprised not one person mentioned the fact that the client is connecting to the php app means that php could simply pick up the client's IP, no need for any external services.

I'm not sure how php would do that but the script is sending $MYIP back to php and so long as php would put the connecting IP into $MYIP, then I would not even need the code posted for this question.

php code section is;

 myip = "' . $_POST['myip']
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