Does ::1/128 count as valid IPv6 address?

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1

Hi

recently, Mikrotik exposed “lo” loopback adapter in ROS v7.14
by default, this interface have ::1/128 address which is rejected by “isValid”

function discover_process_ipv6(&$valid, $ifIndex, $ipv6_address, $ipv6_prefixlen, $ipv6_origin, $context_name = '')
{
    global $device;

    if (! IPv6::isValid($ipv6_address, true)) {
        // ignore link-locals (coming from IPV6-MIB)
        return;
    }

::1/128 is same as 127.0.0.1/8 in v4 world
and 127.0.0.1/8 is accepted as VALID
even 127.0.0.1/32 is VALID

should LNMS accept ::1/128 as valid v6 address ?

walk from device:

ipv6AddrPfxLength[1][fe80:0:0:0:7a9a:18ff:fe4a:51a5] = 64
ipv6AddrPfxLength[11][fe80:0:0:0:7a9a:18ff:fe4a:51a6] = 64
ipv6AddrPfxLength[13][fdff:255:0:0:0:0:0:9] = 64
ipv6AddrPfxLength[13][fe80:0:0:0:c156:1169:199:2079] = 64
ipv6AddrPfxLength[14][fe80:0:0:0:7a9a:18ff:fe4a:51a6] = 64
ipv6AddrPfxLength[15][fe80:0:0:0:7a9a:18ff:fe4a:51a6] = 64
ipv6AddrPfxLength[16][fd00:9:255:0:0:0:0:1] = 64
ipv6AddrPfxLength[16][fe80:0:0:0:7a9a:18ff:fe4a:51a6] = 64
ipv6AddrPfxLength[19][fe80:0:0:0:d0d4:25bb:8d34:53c3] = 64
ipv6AddrPfxLength[25][0:0:0:0:0:0:0:1] = 128
----
ipv6AddrType[1][fe80:0:0:0:7a9a:18ff:fe4a:51a5] = 1
ipv6AddrType[11][fe80:0:0:0:7a9a:18ff:fe4a:51a6] = 1
ipv6AddrType[13][fdff:255:0:0:0:0:0:9] = 2
ipv6AddrType[13][fe80:0:0:0:c156:1169:199:2079] = 1
ipv6AddrType[14][fe80:0:0:0:7a9a:18ff:fe4a:51a6] = 1
ipv6AddrType[15][fe80:0:0:0:7a9a:18ff:fe4a:51a6] = 1
ipv6AddrType[16][fd00:9:255:0:0:0:0:1] = 2
ipv6AddrType[16][fe80:0:0:0:7a9a:18ff:fe4a:51a6] = 1
ipv6AddrType[19][fe80:0:0:0:d0d4:25bb:8d34:53c3] = 1
ipv6AddrType[25][0:0:0:0:0:0:0:1] = 2
2

No 127.0.0.1 is IPv4 and ::1 is IPv6 both are localhost but they are not “the same”
::1/128 is localhost with full subnet mask, so that is ::1 as address with 128 prefix len

127.0.0.1/8 is the full 127.0.0.0-127.255.255.255 range and not just the address.
Reading the comment ignoring link-local (as in fe80::/10) seems to be the goal, I would absolutely accept the premise that ::1 is not a valid global address. so should ? discover_process_ipv6 ignore link-local and localhost IPs on interfaces?

3

There is no way to disambiguate ::1 or 127.0.0.1 from device to device.
localhost ips do not contain any useful information, so they are rejected.

4

The OP asked about the localhost IPs, but the comment on isValid which according to OP return false, only mentions “link-locals” , not localhosts, so there might be some inconsistencies here.

I totally agree that they probably should be rejected, but reading OP they are not for IPv4, and the comment is not clear in the OP snippet.

5

OP linked the wrong bit of code. Under the context of the IPv6 module (of which they are showing code from an old version), locahost should always be rejected.

Here is a look at the isValid function:

    public static function isValid($ipv6, $exclude_reserved = false)
    {
        $filter = FILTER_FLAG_IPV6;
        if ($exclude_reserved) {
            $filter |= FILTER_FLAG_NO_RES_RANGE | FILTER_FLAG_GLOBAL_RANGE;
        }

        return filter_var($ipv6, FILTER_VALIDATE_IP, $filter) !== false;
    }

As you can see $exclude_reserved also requires it to be a global IP, which is exactly what we want for the IPv6 Addresses module.

The only issue is that the comments/option name are slightly misleading.

1 Like
6

Yes, that is what I tried to say, I’m sorry if it came of in any other way.

7

we were both just trying to clarify :wink: