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
connectivity.
> 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 169.254.0.0/16).
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 169.254.192.100/16 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 169.254.192.123
That command will scan common ports on the unknown device and attempt to
guess its operating system.