"Phillip Remaker" <> wrote
>> My GF is getting one of these soon. I've had lots of problems with
>> getting probed from what looks like infected external machines, but
>> I've got a Cisco 803 on which you can set this up...
>
>Well, all of the Linksys models stop all unsolicited inbound traffic on the
>"WAN" port unless explicitly permitted (since it is really a Network Address
>Translation (NAT) box, not a 'router'), so that should stop the probing at
>the door. Using access-lists is moot, since the default is to deny
>everyone. Compare this to IOS routing, where packets are allowed in unless
>explicitly denied. Note that IOS NAT also denies all inbound packets unless
>it matches an outbound stream or is explicitly permitted.
I don't understand the last 2 lines above, unless you assume that the
access list start with a simple 'permit any any' line; then you have
to start restricting things...
The reason I posted the Linksys question is because over the last week
or two I have spent many hours, very well assisted by another man from
around here, setting up the following 803 access list
outbound:
>access-list 100 permit tcp any any eq www
>access-list 100 permit udp any any eq domain
>access-list 100 permit tcp any any eq domain
>access-list 100 permit tcp any any eq nntp
>access-list 100 permit tcp any any eq pop3
>access-list 100 permit tcp any any eq ftp
>access-list 100 permit tcp any any eq ftp-data
>access-list 100 permit tcp any eq ftp-data any
>access-list 100 permit tcp any any established
inbound:
>access-list 150 permit tcp any any established
>access-list 150 deny tcp any any eq ftp-data
>access-list 150 permit tcp any eq ftp-data any
>access-list 150 deny icmp any any echo
>access-list 150 permit icmp any any
>access-list 150 permit tcp any any eq ident
>access-list 150 permit tcp any any eq smtp
>access-list 150 permit udp any eq domain any
>access-list 150 deny ip any any
just so that the router works for the normal internet stuff (http,
pop3 email, ftp) while numerous Blaster (and possibly other) inbound
traffic does not keep the line up for long enough to stretch my normal
20hr/mo online time to beyond 250hrs/mo and get me kicked off the
flat-rate ISP !!
I am getting a Blaster attack every minute at least, from different
people.
Until a few months ago, I was able to use
>access-list 100 deny udp any any eq netbios-ns
>access-list 100 deny udp any any eq netbios-dgm
>access-list 100 deny udp any any eq netbios-ss
>access-list 100 deny udp host 0.0.0.0 eq 135 any
>access-list 100 permit ip any any
(straight out of the Cisco 800 handbook) and that worked for the
previous 3 years without a single problem.
Times are changing...
Is the above sort of thing possible on the Linksys 54G wifi broadband
router, or would people rely on the fact that with broadband nobody
cares (or notices) what gets retransmitted following the receipt of
Blaster packet?
Peter.
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