Geekzone: technology news, blogs, forums
Welcome Guest.
You haven't logged in yet. If you don't have an account you can register now.

643 posts

Ultimate Geek

# 11890 16-Feb-2007 12:06

it won't be news to most of you techies that ARP data from leaks out of the Motorola cable modems on Telstra's network. I've always been happy to ignore this but a friend of mine told me an interesting story last night.

He recently replaced a dying linksys router with a 3com Office Connect one, very nice router. A couple of days later Telstra shut down his modem and refused to start his service again until he changed his local area network's IP addresses and subnet. He was using the RFC1918-defined private network address space of also. So it would seem that the 3com router was smarter than the Linksys and seeing ARP data on it's external/WAN interface decided to proxy ARP between networks.

Spurious ARP data being allowed to enter private networks is a slight concern but the fact that his ARP data was allowed to enter and cause problems in the TCL network is a major concern. People could be poisioning Telstra's cache's and potentially sniffing other people's Internet connections, switched ethernet networks still are vulnerable and I'd like to know what Telstra's excuse for this huge vulnerability is.

Sniffing the glue holding the Internet together

Create new topic
28369 posts

Uber Geek

Biddle Corp
Lifetime subscriber

  # 61010 16-Feb-2007 12:45
Send private message

This issue has been debated many times over the years and never seems to reach a resolution. I was one of a handful of people who got to trial the cable modem network around 10yrs ago now and it was something that the guys were talking about (not that I actually understood what they were really talking about back then!) because the cable modem is really just a ethernet bridge and you can snoop on all ARP traffic on the network.

Is this issue in particular only affecting

643 posts

Ultimate Geek

  # 61011 16-Feb-2007 12:55

yes AFAIK it's the traffic eminating from the modem causing the problem. the 3com isn't doing anything particularly wrong by proxying ARP it sees on both interfaces.

But surely they could VLAN the customer traffic seperately to the network/management traffic?

Sniffing the glue holding the Internet together


4571 posts

Uber Geek


  # 61015 16-Feb-2007 13:49
Send private message

The amount of ARP traffic is fairly large as well.  I switched to a WRT54G router running DD-WRT to get some SNMP monitoring and while I use most of my 20 Gb cap, the amount of extra traffic seen by my router is well into 10 gb.

Previously known as psycik

OpenHAB: Gigabyte AMD A8 BrixOpenHAB with Aeotech ZWave Controller, Raspberry PI, Wemos D1 Mini, Zwave, Xiaomi Humidity and Temperature sensors and Bluetooth LE Sensors
Media:Chromecast v2, ATV4, Roku3, HDHomeRun Dual
Windows 10
Host (Plex Server/Crashplan): 2x2TB, 2x3TB, 1x4TB using DriveBender, Samsung 850 evo 512 GB SSD, Hyper-V Server with 1xW10, 1xW2k8, 2xUbuntu 16.04 LTS, Crashplan, NextPVR channel for Plex,NextPVR Metadata Agent and Scanner for Plex

836 posts

Ultimate Geek


  # 61048 16-Feb-2007 20:17
Send private message

barf:  the 3com isn't doing anything particularly wrong by proxying ARP it sees on both interfaces.

What, sounds like a gaping security hole if that default behaviour.

I agree VLAN'ing off of management traffic is a sensible idea, I assume there is some technical reason for this not being implemented however as it seems blindingly obvious :)

1 post

Wannabe Geek

  # 61085 17-Feb-2007 14:46
Send private message

barf: the 3com isn't doing anything particularly wrong by proxying ARP it sees on both interfaces.

What, sounds like a gaping security hole if that default behaviour.

The router has a selectable option for 'Proxy ARP' that is not on by default, and I have never had it on.

Create new topic

Switch your broadband provider now - compare prices

Twitter and LinkedIn »

Follow us to receive Twitter updates when new discussions are posted in our forums:

Follow us to receive Twitter updates when news items and blogs are posted in our frontpage:

Follow us to receive Twitter updates when tech item prices are listed in our price comparison site:

News »

Chorus to launch Hyperfibre service
Posted 18-Nov-2019 15:00

Microsoft launches first Experience Center worldwide for Asia Pacific in Singapore
Posted 13-Nov-2019 13:08

Disney+ comes to LG Smart TVs
Posted 13-Nov-2019 12:55

Spark launches new wireless broadband "Unplan Metro"
Posted 11-Nov-2019 08:19

Malwarebytes overhauls flagship product with new UI, faster engine and lighter footprint
Posted 6-Nov-2019 11:48

CarbonClick launches into Digital Marketplaces
Posted 6-Nov-2019 11:42

Kordia offers Microsoft Azure Peering Service
Posted 6-Nov-2019 11:41

Spark 5G live on Auckland Harbour for Emirates Team New Zealand
Posted 4-Nov-2019 17:30

BNZ and Vodafone partner to boost NZ Tech for SME
Posted 31-Oct-2019 17:14

Nokia 7.2 available in New Zealand
Posted 31-Oct-2019 16:24

2talk launches Microsoft Teams Direct Routing product
Posted 29-Oct-2019 10:35

New Breast Cancer Foundation app puts power in Kiwi women's hands
Posted 25-Oct-2019 16:13

OPPO Reno2 Series lands, alongside hybrid noise-cancelling Wireless Headphones
Posted 24-Oct-2019 15:32

Waikato Data Scientists awarded $13 million from the Government
Posted 24-Oct-2019 15:27

D-Link launches Wave 2 Unified Access Points
Posted 24-Oct-2019 15:07

Geekzone Live »

Try automatic live updates from Geekzone directly in your browser, without refreshing the page, with Geekzone Live now.

Support Geekzone »

Our community of supporters help make Geekzone possible. Click the button below to join them.

Support Geezone on PressPatron

Are you subscribed to our RSS feed? You can download the latest headlines and summaries from our stories directly to your computer or smartphone by using a feed reader.

Alternatively, you can receive a daily email with Geekzone updates.