Hi, Can you do a step-by-step tut on ASSP v2.3.3 on CentOS 6.4 and Ubuntu LTS 12.04.2 using the flows below: as well as what to change in the web interface to make the config work: pcs: pc1-Firewall 192.168.1.1 (iptables) pc2-ASSP+SMTP_Relayer 192.168.1.5 (ASSP v2.3.3) pc3-Exchange 192.168.1.20 (Exchange 2013) 1) simple flow: (IN) Internet-->25/465/587_ASSP-->25_Exchange (OUT) User-->225_ASSP-->25_Exchange-->Internet Exchange send email via DNS. 2) best flow: (IN) Internet-->25/465/587_ASSP-125_SMTP_Relay-->25_Exchange (OUT) User-->25/465/587_Exchange-->225_ASSP-125_SMTP_Relay-->Internet Exchange send email via SSL/TLS 192.168.1.5:225 Note: 1. make sure not an open-relay/spoof attack 2. firewall only allow port 25 out from: flow1: 192.168.1.20, flow2:192.168.1.5 3. In flow2 Relay to internet only if email comming from port 225 on ASSP 4. Secure communication between: a) ASSP and SMTP_Relay b) SMTP_Relay and Exchange c) Exchange and ASSP d) Users and Exchange/ASSP 5. is there a way in linux to only allow a program (say postfix) to access a port (say port 25), maybe using iptables? Thank you. fbifido[at]gmail[dot]com
