Looking for help with packet-chasing ...

Tim ignored_mailbox at yahoo.com.au
Wed Jun 8 04:32:00 UTC 2011

On Tue, 2011-06-07 at 18:36 +0100, Timothy Murphy wrote:
> I'm wondering if there is some program that will tell me
> where packets are travelling around my home LAN?
> I tried swapping my server to another machine on the LAN
> (an HP MicroServer), attaching the ADSL line to the MicroServer.
> This worked fine on the MicroServer, with access to the internet, etc.
> But I lose the connection from my laptop(s) when I do this.

What do you lose?  Connection to the internet, connection to your new

Did you take the clients off-line and back on again, or renew their
leases (done on the clients)?  If not, they'll carry on using what they
found out about when they first connected.

> I guess I need to read a tutorial on route (or perhaps ip?).
> I changed 
>         option routers        ;
> to the new server in /etc/dhcpd.conf (re-starting the dhcpd service)
> and changed the old address to the new everywhere I could find it.

"option routers" will set the default gateway to all DHCP clients,
assuming that those clients don't have DHCP client configuration files
that ignore some aspects of the DHCP server information.

> The old address is mentioned as "option routers" in some leases files,
> but I'm not sure if I can safely delete these?

If you take the clients off-line and go back on-line (ifup/ifdown), or
tell them to renew their lease (*), they should poll the DHCP server to
check for changes to configurations.

* "dhclient -r -l" probably should do it, but it's a long time since I
manually did this, and I don't want to try doing it at the moment while
I'm in the middle of doing things.  See the dhclient man file.

As a brute force method.  Take them off-line, delete their configuration
information, put them back on-line.

[tim at localhost ~]$ uname -r

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