Re: Fw: Can a daemon listen only on some interfaces?
At 09.12.2001, email@example.com wrote:
> And thanks for all the replies. In fact I was most interested to hear
> that you could not make daemons listen on only one interface but you
> could make them bind to an IP address range. I guess that is what I
> achieved in my postfix main.cf file with the line:
> inet_interfaces = localhost
Yes, if you take a look with "netstat -ln | grep 25" you will see
something like that:
tcp 0 0 127.0.0.1:25 0.0.0.0:* LISTEN
This means, that the service is listening on 127.0.0.1. The Interface is
"lo". If an attacker in the same network sets a route like that:
127.0.0.1 Gateway <your official ip address> Interface <his
he can reach your service bound to 127.0.0.1. And this without
activating ip_forward on your computer!
This is easy to circumvent with ipchains or iptables.