Jeff Boyce
2016-04-14 19:39:29 UTC
Greetings -
As I was investigating some networking issues in my office I ran across
a dns network issue that I would like to resolve. I have dnsmasq
configured on a CentOS 6 VM for our office network. The desktops in the
office receive fixed IP addresses from dnsmasq using the option
dhcp-host=computername, ipaddress, infinite.
As I was investigating my other issue I noticed that one of the desktop
system was not getting the IP address I was expecting. I forced it to
renew it's lease so I could see what appeared in the log file. To
paraphrase the log message, the host was not configured with IP Address
xxx.xxx.xxx.106 because it is leased to another system at MAC Address
aa:bb:cc:dd:ee:ff.
So that lead me to look at the lease file to see it I could tell which
system was associated with that MAC Address. The lease file listed a
lease time expiry of zero (I am assuming that refers to infinite lease
time), the MAC and IP Addresses, but had a * for the Computer Name. I
suspect that this MAC Address is for a computer that had been retired
and removed from the network, but am unable to confirm it any other
way. So I am trying to figure out a safe way to force a lease renewal
system-wide so that it will clear and re-populate the lease file (and
cached memory). That way I would know for sure whether the system that
is listed in the lease file with IP Address xxx.xxx.xxx.106 is a retired
system or not.
I searched the list archives and found a similar situation where someone
was asking how to delete an entry from the lease file for a system that
they *knew* was no longer in use. In that case the recommendation was
to (1) stop dnsmasq, (2) edit the lease file, then (3) restart dnsmasq.
However, in my situation I don't know who this computer is, and whether
it is retired and removed from the network or not. Also since my
configuration file has lease times set to infinity, whether that might
complicate the situation.
Can someone suggest a safe approach to clearing and re-populating the
lease file in this situation. I suspect that I will need to change my
configuration lease time to something short, but don't know what
additional things I might need to do, and how to sequence any steps.
Thanks.
Jeff
As I was investigating some networking issues in my office I ran across
a dns network issue that I would like to resolve. I have dnsmasq
configured on a CentOS 6 VM for our office network. The desktops in the
office receive fixed IP addresses from dnsmasq using the option
dhcp-host=computername, ipaddress, infinite.
As I was investigating my other issue I noticed that one of the desktop
system was not getting the IP address I was expecting. I forced it to
renew it's lease so I could see what appeared in the log file. To
paraphrase the log message, the host was not configured with IP Address
xxx.xxx.xxx.106 because it is leased to another system at MAC Address
aa:bb:cc:dd:ee:ff.
So that lead me to look at the lease file to see it I could tell which
system was associated with that MAC Address. The lease file listed a
lease time expiry of zero (I am assuming that refers to infinite lease
time), the MAC and IP Addresses, but had a * for the Computer Name. I
suspect that this MAC Address is for a computer that had been retired
and removed from the network, but am unable to confirm it any other
way. So I am trying to figure out a safe way to force a lease renewal
system-wide so that it will clear and re-populate the lease file (and
cached memory). That way I would know for sure whether the system that
is listed in the lease file with IP Address xxx.xxx.xxx.106 is a retired
system or not.
I searched the list archives and found a similar situation where someone
was asking how to delete an entry from the lease file for a system that
they *knew* was no longer in use. In that case the recommendation was
to (1) stop dnsmasq, (2) edit the lease file, then (3) restart dnsmasq.
However, in my situation I don't know who this computer is, and whether
it is retired and removed from the network or not. Also since my
configuration file has lease times set to infinity, whether that might
complicate the situation.
Can someone suggest a safe approach to clearing and re-populating the
lease file in this situation. I suspect that I will need to change my
configuration lease time to something short, but don't know what
additional things I might need to do, and how to sequence any steps.
Thanks.
Jeff
--
Jeff Boyce
Meridian Environmental
Jeff Boyce
Meridian Environmental