[ale] assigning ip to second interface

[Gary Maltzen]

1) Apparently you *ASSUME* that 169.254 is the ONLY address block managed by
ISI.EDU; that the address block is reserved by ISI.EDU is misleading - in
conjunction with IANA, ISI.EDU holds the reservation on all the
reserved-for-private-use blocks.

2) "what prevents them from colliding" is the algorithm for randomly
selecting one of the 65,534 addresses in this block and checking to see if
it is already in use. NOTE that this block is intended for "Local Link" use;
i.e. locally networked appliances. This is an alternative for use when there
is no BOOTP/DHCP server.

3) Windows 98, failing to find a DHCP server, will use this algorithm. If
you are seeing attempts to access your network from 169.254, it is probably
poorly configured Win98 systems.

# whois 169.254.1.1

Internet Assigned Numbers Authority (IANA)
 (NETBLK-LINKLOCAL)
   For use with Link Local Networks
   Information Sciences Institute
   University of Southern California
   4676 Admiralty Way, Suite 330
   Marina del Rey, CA 90292-6695

   Netname: LINKLOCAL
   Netblock: 169.254.0.0 - 169.254.255.255

# whois 192.168.1.1

IANA
 (IANA-CBLK-RESERVED)
   Internet Assigned Numbers Authority
   Information Sciences Institute
   University of Southern California
   4676 Admiralty Way, Suite 330
   Marina del Rey, CA 90292-6695

   Netname: IANA-CBLK1
   Netblock: 192.168.0.0 - 192.168.255.0


<jtrostel at mindspring.com> wrote:


> If devices automatically assign themselves some address in the ISI.EDU
domain, what prevents them from colliding with real devices in this domain?
Doesn't this also lead to devices that should be in some other domain
appearing to be in the "wrong" ISI.EDU domain?
>
> Does this explain the frequent access attempts on my systems from various
machines claiming to be from this domain?
>
> Gary Maltzen <maltzen at MM.COM> wrote:
> __________
> >
> >>tewkewl at mindspring.com wrote:
> >> >
> >> > A further note....
> >> >
> >> > 192.168 is used for autoconfiguration when a client is unable to
obtain an ip address from dhcp... It would be a safer bet to change the
netwrok number now before you get too deep into experimenting... :)
> >>
> >>Okay, someone set me straight.  I'm reading in front of me that Class C
> >>private addresses are in the range of 192.168.0.0 through
> >>192.168.255.255.  If this is correct, you shouldn't be seeing them via
> >>dhcp.  Has something changed?
> >
> >Actually, it is 169.254.*.* that is used for device autoconfigure. This
block is assigned to ISI.EDU and reserved for self-discovery. Devices using
this are supposed to randomly pick an address in this block and poll to see
if any other system is using the address, repeating this process with up to
ten different addresses or until they find a free address.
> >
> >RFC-1918 (reserved for private LAN) address blocks are
> >   10.0.0.0 - 10.255.255.255
> >   172.16.0.0 - 172.31.255.255
> >   192.168.0.0 - 192.168.255.255


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