I am setting up tomcat server on my Centos 5.5 machine. I've been advised to run tomcat on 8080 as non root user and redirect traffic to it from port 80.

I searched and found the following iptables commands for this:

# iptables -t nat -A PREROUTING -p tcp --dport 80 -j REDIRECT -to-ports 8080
# iptables -I INPUT -p tcp --dport 8080 -j ACCEPT

I have a doubt:
Tomcat is not accessible via port 80 without the second command. But the second command opens 8080 and makes it accessible over the internet (tomcat is accesible via both: www.<website>.com and http://<ip address>:8080). This doesn't seem right. Is there some simple (iptables) way to redirect traffic "internally" from port 80 to 8080 without having to open 8080 to the internet.

Thanks

You could try the approach being discussed here for a similar requirement.

BTW, why can't you just make it listen on port 80 in order to avoid all of this?

thank you win32sux

I don't want to run tomcat on port 80 because that would have to be done as root and I want to avoid logging in as root regularly for the administration, testing, deployment etc.

For someone who reads this later: I tried a slight variation of the iptables mangle command mentioned in post linked above and it restricts access to 8080 from outside/internet while allowing the redirects from port 80.

I had to use -I in second rule instead of -A, as in the post linked above, this might depend on sequence of rules in your iptables

Can someone comment on how good a solution this is for simple deployment of tomcat on 8080?

No problem.

That's a good reason IMO.

That said, isn't it kind of odd that the program doesn't have root privilege dropping as a feature? I've never used Tomcat so I don't really know the particulars. In any case, I understand why you're doing this now – and running daemons as root is almost always a terrible idea.

I can't comment on Tomcat, but the iptables technique seems pretty solid to me. I've used it myself, and have recommended it to other members who report satisfactory results. See this thread, for example.