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I currently use net.ipv6.conf.all.use_tempaddr=2 to get IPv6 privacy addresses (which have a random host part are and regenerated a couple times a day). I need dynamic DNS because the computer is connected to different networks and that changes the network part of the address. I'm using curl to download a dynamic DNS url and want it to use the Non-random address that uses my MAC. How can I make curl prefer the non-privacy address?

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You can force curl to use a specific source address with the --interface option of curl, e.g.

curl --interface 2001:db8::f00:1234

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This could work, but I would have to make some kind of script to determine the address to tell curl to use. I was kind of hoping for a way to say to use the non-privacy address without writing a script to decide which is which. – Azendale Jun 22 '11 at 13:46
There isn't really a way to do that, as an interface can have multiple global addresses, and I don't believe that curl currently allows preferring the public addresses instead of the temporary address except by manually binding to a particular interface/ip address – ajmitch Jun 23 '11 at 22:56
Do you mind if I edit your answer with the script I put together so it's a complete answer to my problem? You could then edit the script if you thought there was a better way to do it. – Azendale Jun 29 '11 at 20:31
@Azendale: you can create a new answer which you accept, but upvote this one because it helped you. – Lekensteyn Jun 29 '11 at 21:27
up vote 1 down vote accepted

I used ajmitch's answer and some scripting to do this. (If anyone has a better way of getting the address, I would be glad to hear it.) You'll need to install curl

#! /bin/sh
# (C) 2011 Erik B. Andersen <>
# Licensed under the latest version of the GPL as published by the Free Software Foundation

# Don't bother to reload when lo is configured.
if [ "$IFACE" = lo ]; then
        echo "Interface lo; skipping"
        exit 0

if [ ! -e /usr/bin/curl ]; then
        echo "Curl not installed; skipping"
        exit 0
if [ ! -e /sbin/ifconfig ]; then
        echo "Ifconfig not installed; skipping"
        exit 0
if [ ! -e /bin/grep ]; then
        echo "Grep not installed; skipping"
        exit 0
if [ ! -e /usr/bin/tr ]; then
        echo "Tr not installed; skipping"
        exit 0
if [ ! -e /usr/bin/tail ]; then
        echo "Tail not installed; skipping"
        exit 0


echo "Running curl"
curl --interface $(/sbin/ifconfig ${Interface} | /bin/grep "Global" | /usr/bin/tr "/" "\n" | /usr/bin/tr " " "\n" | /bin/grep "ff:fe"| /usr/bin/tail -n 1) -6 http://${Hostname}:${Password}${Hostname}

exit 0
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