Fastest way to change IP addresses
jamie at gnulife.org
Sat Nov 15 12:27:01 PST 2003
On Sat, 15 Nov 2003, Matthew Seaman wrote:
> On Sat, Nov 15, 2003 at 01:35:52PM -0600, Jamie wrote:
> > I want to change the IP address from 184.108.40.206 to 220.127.116.11
> > on a FreeBSD machine as quickly as possible. Despite my efforts, I can
> > only get the change to work by editing rc.conf and rebooting the machine.
> > Isn't there a more elegant way?? The man page for ifconfig seems to cover
> > changing IP ALIASES, but not the primary IP of an interface.
> > In order to switch to 18.104.22.168 I've tried:
> > 1) ifconfig de0 22.214.171.124 255.255.255.0
> > ifconfig -a then gives me:
> > fxp0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> mtu 1500
> > inet 126.96.36.199 netmask 0xffffff00 broadcast 188.8.131.52
> > ether 00:03:47:b1:d6:1c
> > media: 10BaseT/UTP status: active
> > But then I cannot ping the gateway,
> Yes -- you're doing everything right in order to change the IP number.
> Except that you seem confused as to whether the network interface is
> de0 or fxp0 -- I assume that's just a flub in your e-mail, and not
> what you've actually done...
> If it isn't that, then the problem may lie within your network gear.
> This may have cached the MAC address belonging to your machine as
> associated with first IP number and is getting confused by the
> renumbering. If you wait for a while it should eventually sort itself
> out. How long you have to wait depends on a number of things
> including the make of routers and switches -- it could be as long as
> 20 minutes.
> One way that you might get round this problem would be to add the new
> address as an alias:
> # ifconfig de0 inet 184.108.40.206 netmask 0xffffffff alias
> In theory you could then go on to swap the netmasks for the two
> addresses, thus making the second one the primary address, and then
> delete the first address. Possibly with some sort of delay between
> each operation to let verything adjust. But no guarrantees that will
> work. You'll have to experiment.
I found another machine here running a newer version of FreeBSD and
tried it. It worked the way it should. The old machine was running FreeBSD
3.4, and the new machine is running 4.8. Maybe the problem has to do with
And yes, that was a flub in the email.
Thanks for the suggestions,
> Dr Matthew J Seaman MA, D.Phil. 26 The Paddocks
> Savill Way
> PGP: http://www.infracaninophile.co.uk/pgpkey Marlow
> Tel: +44 1628 476614 Bucks., SL7 1TH UK
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