Hacking The 3Com 3C19504:
Device Problems

Christopher Rath

May, 2002

C A U T I O N

Most of the actions I describe herein result in the voiding of the device’s warrantee. I take no responsibility for any damage which might result from anyone attempting to duplicate my work. In other words, you bear all responsibility for your own actions. If you break your 3C19504 then it’s your own fault. I do not recommend you reproduce my work! This information is offered for entertainment purposes only, no warrantee is offered or implied.

Known Problems

DHCP Release

While there are several known problems documented on the 3Com support website, there only one that is of any real consequence to me (copied from the 3Com Knowledge Base):

SolutionID:
2.0.96116760.3593649
Title: 3Com Internet Server - Does not release DHCP addresses
Fact 3Com Internet Server
Fact DHCP
Symptom DHCP address not released
Cause When activating DHCP on the internet server, once an address is used, it is not released when the connection is disconnected after the lease time has expired. This address will also not be released after a power-cycle.
Fix Product is EOL and will not be fixed
Fact Search group - Network Servers
Fact Last Reviewed: March 2002

This problem presents me with a real issue because of the manner in which my ISP authenticates connections: instead of using a special hostname for the connecting network device, the ISP allows one unique MAC address to hold an IP address at any one time (via the cable modem). The ISP is flexible, in that if the current device does a “DHCP release” action then a different MAC address may request an IP address on the cable modem. If my 3C19504 gives me trouble and I need to swap it out for my old firewall, I will have to either wait for the lease on the IP address to expire (could take up to 2 weeks), or call my cable company and have them reset the IP address manually (not a preferred option).

What the 3C19504 should do is issue a “DHCP release” at shutdown; however, it doesn’t.  Investigation of the init.d files shows that /etc/rc.d/init.d/dhcpcd doesn’t create the appropriate file in the /var/lock/subsys/ directory to show that the dhcpcd subsystem successfully started.  As a result, at system shutdown time the dhcpcd kill script doesn’t get executed.  This is easily fixed; however, be aware that resetting the 3C19504 to its factory defaults causes /etc/rc.d/init.d/dhcpcd to be overwritten. 

Other “Bugs”

Here are the other other bugs I have encountered:


©Copyright 2002, Christopher & Jean Rath
Telephone: 613-824-4584
Address: 1371 Major Rd., Ottawa, ON, Canada K1E 1H3
Last updated: 2007/02/16 @ 09:53:03 ( )