• Keir Fraser's avatar
    tools/docs: Fix example and default IP addresses. · 487e884d
    Keir Fraser authored
    In various places in documentation and code, IP addresses are provided
    as examples, defaults, or dummy configuration.  In general the
    specific IP addresses used in Xen are not always appropriate.  (For
    example, 1.2.3.4 is used in a few places!)
    
    The following addresses should be used:
     * For examples and documentation, 192.0.2.0/24.  (See RFC3330.)
     * For defaults for private networks, a random network from RFC1918.
       I have randomly selected 172.30.206.0/24 for this purpose and
       documented this in at the only registry I know of,
       www.ucam.org/cam-grin.  This network should henceforth be used for
       default configurations of local bridges, test networks, etc. in
       Xen tools.
    
    The following addresses should NOT be used:
     * 10.0.*.*, 10.1.*.*, 192.168.0.*, 192.168.1.*, etc.  Using these
       addresses gives greatly increased likelihood of collision, as
       ignorant network administrators and reckless middlebox vendors
       often pick networks from the bottom of 10/8 and 192.168/16.
     * 169.254.*.*.  These are reserved for zeroconf (ad-hoc networking)
       and should not be used for Xen private networks, bridges, etc.,
       etc.  Use of these addresses by Xen scripts causes trouble on hosts
       (eg laptops) which find themselves in ad-hoc networking
       environments.  I think this is not hypothetical (!) since at least
       one Linux distribution have specific code to detect this case and
       cause Xen startup to fail iff the host already has an external
       zeroconf address.
     * 1.2.3.4.  WTF !?
    
    I have also used 127.0.255.255 in one place where apparently a dummy
    address is needed (some Linux kernels won't accept a lack of an NFS
    server address).  If 127.0.255.255 is mistakenly used it is unlikely
    to do any damage to real traffic even if it does escape into the
    network at large.
    Signed-off-by: default avatarIan Jackson <ian.jackson@eu.citrix.com>
    487e884d
Writing_Tests_HOWTO 4.82 KB