O'Reilly logo

Troubleshooting Linux® Firewalls by Michael Shinn, Scott Shinn

Stay ahead with the world's most comprehensive technology and business learning platform.

With Safari, you learn the way you learn best. Get unlimited access to videos, live online training, learning paths, books, tutorials, and more.

Start Free Trial

No credit card required

Chapter 14. SMTP (e-mail)

In this chapter we will cover some of the more common SMTP issues, including sending/receiving mail from the firewall, forwarding SMTP traffic to an internal mail server, and dealing with special circumstances to keep in mind when firewalling SMTP servers.

Common Questions

Q:

Can iptables/netfilter alert via e-mail?

A:

Natively, no, it cannot. There are numerous ways to add in alerting capabilities with user space tools such as the IDS snort (http://www.snort.org).

Q:

Can firewall rules be used to route traffic based on the recipient?

A:

The short answer is no. The (very) long answer is yes, but you would need to use something like iproute2 (ftp://ftp.inr.ac.ru/ip-routing/) or an application layer proxy. It is also possible to ...

With Safari, you learn the way you learn best. Get unlimited access to videos, live online training, learning paths, books, interactive tutorials, and more.

Start Free Trial

No credit card required