Problems with Updates

[Mario Vukelic]

On Tue, 2008-10-28 at 21:47 -0300, Derek Broughton wrote:
> Of course - _every_ client opens a port. 

I should have phrased it more explicitly. If you read the thread (or
even just the particular post I linked to) you will note that the point
was that the dhcp client opens a UDP port. 

A client that listens on a TCP port knows who he is talking to and will
only accept packets from that particular host. This is different for a
UDP port, which the dhcp client listens on. That port will basically
accept anything from the LAN that is sent to it.

Don't take my word for it, read what Scott James Remnant [1] has to say:

"No, it's still an open port.  UDP lacks any form of checking that things
received are the expected responses, and while the port is open for the
response anything can be sent to it (this is safe-guarded with TCP,
which is why TCP connections aren't considered "open ports")."
https://lists.ubuntu.com/archives/ubuntu-devel/2006-July/019174.html

A laptop, depending on usage, might be frequently in a hostile
environment like random open wifi networks, municipal networks,
airports, etc. I cannot imagine what you'd have to say to make me
consider it an acceptable practice to run a possibly unpatched dhcp
client under such conditions. Oh, and add DNS requests to the mix, which
are also answered via UDP.

[1] https://wiki.ubuntu.com/ScottJamesRemnant