last, lastb not reporting ipv6 address from ssh

[sffroelich]

with ssh login successes or failures, using IPv6, checks using the "-i" option for /usr/bin/last or /usr/bin/lastb do not display the correct IP address.

it appears to be reporting the ipv6 address "fc00:dead::2", or "fc00:dead::3" ass the same address, namely
252.0.222.173

i believe the logged address has stripped "fc", "00", "de", and "ad" (and nothing else) from the first 32 bits of the address, then converted each hex unit to decimal, and logged them in dotted-quad (IPv4) addresses.

while not directly a security vulnerability, last and lastb are vital tools for monitoring the login activity on systems.

regards,
sff
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1) Description: Ubuntu 14.04.3 LTS
Release: 14.04
2) apt-cache policy sysvinit-utils
sysvinit-utils:
  Installed: 2.88dsf-41ubuntu6.2
  Candidate: 2.88dsf-41ubuntu6.2
  Version table:
 *** 2.88dsf-41ubuntu6.2 0
        500 http://us.archive.ubuntu.com/ubuntu/ trusty-updates/main amd64 Packages
        100 /var/lib/dpkg/status
     2.88dsf-41ubuntu6 0
        500 http://us.archive.ubuntu.com/ubuntu/ trusty/main amd64 Packages
3) i expect the full IPv6 address (in v6 notation) written, when applicable, for "-i" output from last, and lastb
4) non-unique IPv4 addresses are reported instead of the correct ipv6 address.