How to curl using IPv6 address?

Question

I have a VPS with a /64 IPv6 assigned to it. When I try to curl using one of the IPs in the block, this is the error I get:

curl --interface '2a02:c207:2010:1077::2' http://example.com
curl: (45) bind failed with errno 99: Cannot assign requested address

What exactly do I need to do to fix this? Shouldn't I be able to use any IP on the machine when logged in as root?

Basically I just need the ability to curl using any IPv6 assigned to the VPS.

Answer 1

after some testing, I find the following command works:

$ curl -g -6 'http://[fe80::3ad1:35ff:fe08:cd%eth0]:80/'

interface 'eth0' is the interface with ipv6 enabled, so you may need to replace it with something else.

and just in case, the telnet command to test ipv6:

$ telnet -6 fe80::3ad1:35ff:fe08:cd%eth0 80

Answer 2

From man curl

--interface specify interface e.g. eth0:1

curl --interface eth0 -g -6 'http://[2606:2800:220:1:248:1893:25c8:1946]:80/index.html' -H 'Host: www.example.com'

It feels like you are expecting curl to manipulate your machine's interfaces to add-and-then-use a specific /128 ? If you want that you will probably have to write your own shell wrapper.