Hi everybody,

I am facing a problem in my network containing
RHEL5 as O/s.

I user a linux machine as a basic router having
IP version4 forwarding settings enable in for
two network let's suppose:-
1)192.168.0.0/24
2)172.16.0.0/16

I like to perform following tasks.
I want to reject a machine of 192.X. series to access
the 172.X network mail server.I am able to perform this
task with iptables by the following command

iptables -I INPUT -p tcp --dport 25 -s 192.168.0.15 -j reject


now i want to send a rejection message to the particular machine
whenever it attempt to access mail server from another network.


if anybody have the solution, plz reply.
thanx in advance

vsaini44, when a firewall denies access, it *can* send back a packet saying access forbidden, but this is done on the ICMP level, which runs on a much lower level than the mail application. It is basically up to the mail application to detect that a connection not works and display the appropriate message to the user.