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Do Plusnet block port scanning ?

N/A

Do Plusnet block port scanning ?

I've just been setup with a new DSL service at the weekend.

Today I asked a friend to scan my IP for any holes from a remote IP, halfway through the scan (Nmap) my IP went dark from his location, I can still ping from my location so I know the line is still up but it has vanished for him.

Do Plusnets routers block the IP's of systems being scanned or is it something else ?

Thanks
R Walker
3 REPLIES
N/A

Do Plusnet block port scanning ?

This will have occured when your friend scanned your port 135.

The Redback units that connect your DSL connection to there network, will detect a connection made to port 135.

These connections are treated as possible Blaster worm (and varients) activity.

As such, all traffic is blocked from your friend connection until your friend attempts to visit a website. This will automaticly be redirected to a specific page detailing why this has happened.

The block is removed from 60 seconds after visiting that page, however, ICMP remains blcoked until he re-connects his ADSL connection.
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Do Plusnet block port scanning ?

Just a small note to this

I use ShieldsUP! to check for any holes in my connection and as far as I can see, this doesnt trigger the block but still allows for a full port scan (as I run Zone Alarm I am currently fully stealthed :lol: )

ShieldsUP! can be found at www.grc.com
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Do Plusnet block port scanning ?

As noted, the block only applies to port 135 as a destination for outgoing traffic, and not incoming like Shields-Up.