[CentOS] OT Strange IP address on home network

Mon Nov 2 00:58:34 UTC 2015
Gordon Messmer <gordon.messmer at gmail.com>

On 11/01/2015 04:40 AM, Timothy Murphy wrote:
> I don't have a directory /etc/sysconfig/networking/ on my CentOS-7 server,
> but I have IPV6INIT=no in /etc/sysconfig/network-scripts/ifcfg-enp{23}s0 .

You're seeing a strange IPv4 address on your network.  Changing IPv6 
won't affect that in any way, and I recommend leaving IPv6 enabled. If 
nothing else, v6 capable applications work better when you have v6 

> Incidentally, I haven't yet worked out how to get any useful information
> from nmap, as suggested by Johnny Hughes - I only get information
> about open ports, which is interesting but not relevant to my query
> about the 169.254.* address appearing in "arp -a" on my server.
> I looked at "man nmap" but there seem to be an infinity of options.

I'm not sure if Linux will cache an ARP entry if the host sends an 
unsolicited update, but you normally won't have a route to that address 
to scan it.  Run 'ip route show' to see if you have a route to the 
address you're seeing (the link-local network is

If you don't see a direct route, then add an address on your system so 
that you can reach the link-local host:
ip addr add dev eth0

Once you have an address on the link-local network, you should be able 
to ping or scan the unknown device.  Use nmap:
nmap -sS -O

That command will scan common ports on the unknown device and attempt to 
guess its operating system.