It can also be addressed directly via:
for all your API needs.
Link-local IPv6 addresses are used as part of the IPv6 network auto-configuration process. Instead of getting an address via DHCP, a NIC will hop on the network with a link-local IPv6 address and with this will have to ability to do further configuration automatically (soliciting neighbors, router, et cetera).
This link-local IPv6 is infered from the NIC’s mac address.
A mac address is 48 bits, an IPv6 address is 128 bits. Here’s the conversion process step by step:
- take the mac address: for example 52:74:f2:b1:a8:7f
- throw ff:fe in the middle: 52:74:f2:ff:fe:b1:a8:7f
- reformat to IPv6 notation 5274:f2ff:feb1:a87f
- convert the first octet from hexadecimal to binary: 52 -> 01010010
- invert the bit at index 6 (counting from 0): 01010010 -> 01010000
- convert octet back to hexadecimal: 01010000 -> 50
- replace first octet with newly calculated one: 5074:f2ff:feb1:a87f
- prepend the link-local prefix: fe80::5074:f2ff:feb1:a87f
Going the other way
A converter to do the same operation in reverse is available here.
There have been a few interesting comments on this post, I encourage you to read them if you want to learn more about this mechanism. Specifically:
54.46% of all emails received on akrin so far got flagged as spam by the excellent Spamassassin. This is actually not too bad compared to high profile mail service providers.
1 email that takes the cake is with a spam score of 42.2 (anything above 4 is not relayed):
Received: from 201-93-229-84.dsl.telesp.net.br (201-93-229-84.dsl.telesp.net.br [126.96.36.199])
From: "Chase bank" <firstname.lastname@example.org>
Subject: urgent security notification for client!
X-Spam-Status: Yes, score=42.2 required=5.0
Content analysis details:
pts rule name description
---- ---------------------- --------------------------------------------------
2.0 RCVD_IN_BL_SPAMCOP_NET RBL: Received via a relay in bl.spamcop.net [Blocked - see <http://www.spamcop.net/bl.shtml?188.8.131.52>]
3.0 RCVD_IN_XBL RBL: Received via a relay in Spamhaus XBL [184.108.40.206 listed in zen.spamhaus.org]
0.9 RCVD_IN_PBL RBL: Received via a relay in Spamhaus PBL
0.6 RCVD_IN_SORBS_WEB RBL: SORBS: sender is a abuseable web server [220.127.116.11 listed in dnsbl.sorbs.net]
1.8 URIBL_PH_SURBL Contains an URL listed in the PH SURBL blocklist [URIs: nilvert.com]
1.9 URIBL_AB_SURBL Contains an URL listed in the AB SURBL blocklist [URIs: nilvert.com]
1.5 URIBL_WS_SURBL Contains an URL listed in the WS SURBL blocklist [URIs: nilvert.com]
1.5 URIBL_JP_SURBL Contains an URL listed in the JP SURBL blocklist [URIs: nilvert.com]
2.0 URIBL_BLACK Contains an URL listed in the URIBL blacklist [URIs: nilvert.com]
3.5 BAYES_99 BODY: Bayesian spam probability is 99 to 100% [score: 1.0000]
4.3 HELO_DYNAMIC_HCC Relay HELO'd using suspicious hostname (HCC)
4.4 HELO_DYNAMIC_IPADDR2 Relay HELO'd using suspicious hostname (IP addr 2)
0.0 FH_HELO_EQ_D_D_D_D Helo is d-d-d-d
1.4 FROM_LOCAL_HEX From: localpart has long hexadecimal sequence
1.9 TVD_RCVD_IP TVD_RCVD_IP
2.8 TVD_PH_SUBJ_URGENT TVD_PH_SUBJ_URGENT
0.7 SPF_NEUTRAL SPF: sender does not match SPF record (neutral)
2.3 SPOOF_COM2COM URI: URI contains ".com" in middle and end
1.6 HTML_IMAGE_ONLY_24 BODY: HTML: images with 2000-2400 bytes of words
0.0 HTML_MESSAGE BODY: HTML included in message
1.4 MIME_QP_LONG_LINE RAW: Quoted-printable line longer than 76 chars
0.1 RDNS_DYNAMIC Delivered to trusted network by host with dynamic-looking rDNS
2.8 DOS_OE_TO_MX Delivered direct to MX with OE headers