Re: lost DHCP connection

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Date: Sun, 17 Jul 2005 00:58:44 +0100

On 15 Jul 2005 20:41:04 -0700, "joe" <jroseve@abac.com> wrote:

>Today at work I tried to use splitmail (a Linux sendmail tool) to send
>an email from a linux box plugged into the network. I configured
>sendmail the same (I ran the same configuration file to make
>/etc/sendmail.cf) as I have it configured at home (where it works
>fine). I have a dialup connection at home to my ISP. At work we have
>a huge network (a wan?)
>
>There are two places in the configuration file which refer to my ISP.
>I didn't know if it would work when the computer was not connected to
>my ISP, but I tried it, anyway.
>
>These are the two lines that refer to my ISP:
>
> define(`SMART_HOST', `smtp2.abac.com')
> .
> .
> .
> MASQUERADE_AS(`abac.com')
>
>I'll supply the rest of my configuration file if anyone needs to see it
>to answer my question. This is the configuration file that was used to
>generate /etc/mail/sendmail.cf.
>
>Anyway, each time (or at least the first two times) I tried sending
>mail with splitmail I got this error message:
>
> Transient parse error -- message queued for future delivery.
>
>Then after the third time failed I thought I would search for the name
>of the smtp server where I work (thinking that I should use it in my
>sendmail configuration). I tried use my internet browser to do this
>and found that I had lost my DHCP connection to the network. I
>couldn't get the connection back. Just for grins, I put sendmail back
>in the configuration it was originally. Still didn't work. I reran
>netconfig. Still didn't work. I shut down and powered off the
>computer and waited about 10 minutes. When I rebooted it still didn't
>work.
>
>I'm just wondering what might have happened. Is DHCP irritable? Did I
>alarm some firewall?
>
>Does anyone have information or opinions that are relevant? I'd sure
>like to know what happened. As today is Friday, I'll be wondering
>about this all weekend long. (And I will be wanting the connection
>back too.)
>
>Thanks.

Running SMTP on a client machine within a LAN, and attempting to
connect to the WAN could/should set off alarm bells. You are doing
almost the same as many email propagated viruses would do.

Secondly, its more than likely that your ISP's smart host will not
allow relaying from your work connection - unless your work uses the
same ISP. You could probably use the same ISP SMTP server as your work
uses, or you could use MX resolution to connect directly to the
recipients mail server.

If you want to get into real trouble you could assign your system a
static IP (though, if DHCP has been disabled for your system's MAC
address - chances are, it might be blocked....full stop.

Get rid of the evidence...sneak the machine out of the building...
remove the software ...whatever. Act fast, they'll be coming to look
for you. You don't work in a multi story building ...do you?
(Remember the openning sequence in "The Matrix") :-)
If you work fast you could swap your network card with one from a
colleagues system - might mean a motherboard swap if the NIC is
integrated. Heheh !!!

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