Very Computer

I have a dynamic ip and a firewall. I have a M$ computer connected to a
FreeBSD computer, which is connected to Internet. Whenever the ip changes,
all my connections to the Internet stop working.

Is there a way to:

-track the new ip as it changes
-restart the network using this new ip (do I have to?)
-restart the firewall (ipfw) using the new ip

...without rebooting?

Any idea?

--
==========================================
Christian Caron

--

Biology/Neuroscience, Pre-med | http://home.uchicago.edu/~dpryan

As for tracking the new IP as it changes, that would depend on which
DHCP client you're using.  If you're using dhclient, there is a dhclient
script, /sbin/dhclient-script, which is called each time the IP address
changes.  Look in there, it may call a local script.  If so, modify
that.  If not, backup the original and modify the master script to call
a local script, and put your notification stuff in there.

    Rod.

Quote:> Hi everyone,

> I have a dynamic ip and a firewall. I have a M$ computer connected to a
> FreeBSD computer, which is connected to Internet. Whenever the ip changes,
> all my connections to the Internet stop working.

> Is there a way to:

> -track the new ip as it changes
> -restart the network using this new ip (do I have to?)
> -restart the firewall (ipfw) using the new ip

> ...without rebooting?

> Any idea?

> --
> ==========================================
> Christian Caron

It probably stop working because your ipfw rules prevent connections using the
new IP. What i did is i defined a $dynip = `ifconfig ep0 | grep inet | grep -v
inet6 | awk '{print $2}'` variable in my rules file and use this variable
instead of hardcoded IP.

I assume here that you get a new IP after a system reboot since changing the
IP while having an active connection is a serious violation of the DHCP
protocol.

Eric.

Quote:> I assume here that you get a new IP after a system reboot since changing the
> IP while having an active connection is a serious violation of the DHCP
> protocol.

--
  j p d (at) d s b (dot) t u d e l f t (dot) n l .

Yes it is (See RFC 2131 on DHCP protocol). DHCP doesn't require an administrator
to manualy configure each new network device. That was the whole point of
developing DHCP.

Eric.

You're right. That's exactly why DHCP will rebind you to the same address on an
active session.

Eric.

 - Lowell

[You can run a DHCP server such that it gives out infinite leases that
don't need to be renewed.  However, this is functionally equivalent to
BOOTP.]

In short, DHCP is a way to configure devices over the network, and one
of its features *is* the ability to change the IP address on a client.
This does, indeed, cause active connections to fail.

  -- Lowell Gilbert

My problems are not when I'm rebooting as the new ip is detected and I use this script to get the new ip in the firewall.

The problem is when my ip is not renewed and I get another one, while the computer is running. Then, I lose my connections. The only way I found to correct the situation is to reboot.

But does somebody know how to "restart the services" (including the firewall ipfw), without rebooting?

Thanks!

--
==========================================
Christian Caron

Quote:>> But it'll still break the existing connections (eg, ssh), so those will
>> need to be re-established, no?

> Yes.  [Actually, I once had a proposal for an extension to DHCP that
> would allow for gradual transfer to a new IP address, but it was never
> implemented by anyone but me, never implemented in any server at all,
> and obviously was never advanced as a standard.]

[1] Mending programs (not being dhcp[cd]) to take hold of the new ip?
    Here _and_ there?

--
  j p d (at) d s b (dot) t u d e l f t (dot) n l .

Quote:>   It also, however, provides for address
> "leases", so that the device doesn't necessarily get to keep using
> that address indefinitely.

1. The lease has expired ( which mean the client haven't tried to *revalidate* his
lease). That will not happen unless you turn off your computer for a while or your
connexion break for more than the lease period.

2. The client has sent a request to release his lease.

The dhcp server will keep the information about the given lease and will try as much
as possible to re-assign the same lease to the same host. In case where the dhcp
server have no more free lease to assing to new clients it will reclaim *unused*
leases and start assigning them to new clients.

Quote:> The device is required to contact the
> server to renew its lease occasionally, and must be prepared, if the
> server so instructs, to stop using the address and start using a new
> one.  A reboot of the device is, thus, not required, and neither is
> direct configuration.

Quote:

> In short, DHCP is a way to configure devices over the network, and one
> of its features *is* the ability to change the IP address on a client.
> This does, indeed, cause active connections to fail.