I recently did an Exchange 2003 to Exchange 2010 migration and one of the Mac users reported a problem when trying to send large (~20MB) emails.  Even though I had removed all transport settings, mailbox settings, organisation settings which might be interfering, after further digging I found the Mac version of Outlook connects via EWS (Exchange Web Services) and this has a separate email limit.  There are many other references of this on the web with various commands and files to edit which people claim solve the problem.  There appears some confusion over the value of the numbers to enter in the web.config – in some versions of Exchange they are in bytes, in others they are in kilobytes.  Here is my fix:

Symptoms

Error seen on user’s computer:

Could not synchronize record: xxxxx to Exchange server: server

With the Error Code: -18493

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I wanted to find out what devices where on my network – wired or wireless.  More over I wanted something that I could acknowledge known hosts and then be alerted when a new or unknown host was found on my network.  I couldn’t find anything FOSS other than some expensive network scanning/management tools, so I set about creating my own using Powershell and NMap – Arp Scan Alert Rogue Hosts

Description

Scans the defined network range using an ARP scan to identify hosts on the network.  For all found hosts the MAC address is checked against a text file known_hosts.txt for a match.  If it is found the description is displayed and the host is identified.  If the MAC address is not found, an email is sent to the configured email address and the MAC address, IP address and time is logged to the file unknown_hosts.txt.  The script repeats the scans at the configured interval.

Screen Shots

All hosts detected:

ARP Scan - All Hosts Recognised

Rogue host detected:

Rogue Host Detected

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