Re: sniffer cable

[Lee Leahu]

Sorry for the delay in response time.  I was waiting on my boss and turns out 
that he found a better method than what I had described, though I will still 
include it for your information.

http://www.spack.org/index.cgi/OneWayEthernet
http://www.sikurezza.org/ml/10_01/msg00222.html
http://home.ie.cuhk.edu.hk/~msng0/sniffing_calbe/
http://web.cuzuco.com/~cuzuco/stealth/

There's also a white paper put out by Intel that titled, 'Cable Discharge 
Event in the Local Area Network Environment'.  Its order number is 249812-001.

Re: sniffer cable

[Lee Leahu]

why don't you just insert a capacitor on one of the transmit leads just large 
enough to cause the network card crc checks to fail but small enought to keep 
the link alive??

Lee Leahu
[EMAIL PROTECTED]

RE: Linux hardware firewall question

[Lee Leahu]

Hi.

I have at home a small network of 4 computers hooked up to an 8 port netgear 10/100 
switch, 
which then feeds into my Linux router / firewall which feeds into my 3com cable modem 
which 
feeds into at&t's cable modem network.

My linux firewall/router is basically a Pentium 233 MMX with 64 Megs of ram and 8Gb 
hard drive.

I wrote a script called 'firewall' and chmod +x 'd it.

 
# allow packet forwarding 
echo 1 > /proc/sys/net/ipv4/ip_forward

# flush tables 
iptables -F INPUT 
iptables -F FORWARD 
iptables -F OUTPUT 
iptables -t nat -F PREROUTING 
iptables -t nat -F POSTROUTING 
iptables -t nat -F OUTPUT

# allow packes from my work 
iptables -A INPUT -i eth0 -s 64.244.234.0/23 -j ACCEPT

# log and drop everything else connecting TO my firewalll 
iptables -A INPUT -i eth0 -m state --state NEW,INVALID -j LOG --log-prefix " 
input-drop " 
iptables -A INPUT -i eth0 -m state --state NEW,INVALID -j DROP

# allow certan packets through to interanll computers 
iptables -A FORWARD -i eth0 -p tcp --dport 4000 -j ACCEPT 
iptables -A FORWARD -i eth0 -p tcp --sport 5190 -j ACCEPT 
iptables -A FORWARD -i eth0 -p tcp --dport 1214 -j ACCEPT

# log and drop everything else 
iptables -A FORWARD -i eth0 -m state --state NEW,INVALID -j LOG --log-prefix " 
forward-drop " 
iptables -A FORWARD -i eth0 -m state --state NEW,INVALID -j DROP

# setup masquerading for outgoing traffic 
iptables -t nat -A POSTROUTING -j MASQUERADE 


This setup has basically worked fine so far. If anyone has any suggestions on my 
setup, 
I am open to suggestions.

At 02:53 2002-02-26, you wrote: 
>I operate a small network of about 5 computers and am considering setting up 
>a pc to operate as a firewall/router for the network. The network does no 
>recieve much traffic at all and trying to figure out hardware wise what I need 
>the topology I have decided to go with is that each box on the network will have 
>its own nic on the pc. Additionally, if anyone can suggest documentation on how 
>to set this up software wise I would appreciate it. 
> 
>I have some experience with iptables, but an unsure exactly how I would set this 
>up? Again any help would be appreciated. 
> 
>Thank you. 
> 
>J. Ferguson

Lee 
[EMAIL PROTECTED]