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What would you like to do?
## The Problem
Standard practices say no non-root process gets to talk to the Internet on a port less than 1024. How, then, could I get Node talking on port 80 on EC2? (I wanted it to go as fast as possible and use the smallest possible share of my teeny tiny little micro-instance's resources, so proxying through nginx or Apache seemed suboptimal.)
## The temptingly easy but ultimately wrong solution:
Alter the port the script talks to from 8000 to 80:
.. and run it as root:
sudo /usr/local/bin/node foo.js
This is a Bad Idea, for all the standard reasons. (Here's one: if Node has access to the filesystem for any reason, you're hosed.)
## One possibly-right way:
Add a port forwarding rule via `iptables`.
### Oh dear familiar feeling: you are a total n00b and know not one thing about iptables.
First, I listed the rules currently running on the NAT (Network Address Translation) table:
[ec2-user@ip-XX-XXX-XX-X ~]$ sudo iptables -t nat -L
Chain INPUT (policy ACCEPT)
target prot opt source destination
Chain FORWARD (policy ACCEPT)
target prot opt source destination
Chain OUTPUT (policy ACCEPT)
target prot opt source destination
I saw nothing, so I felt free to add a rule forwarding packets sent to external port 80 to internal port 8000:
`[ec2-user@ip-XX-XXX-XX-X ~]$ sudo iptables -t nat -A PREROUTING -p tcp --dport 80 -j REDIRECT --to-ports 8000`
When I listed again, I saw a new PREROUTING chain:
[ec2-user@ip-XX-XXX-XX-X ~]$ sudo iptables -t nat -L
target prot opt source destination
REDIRECT tcp -- anywhere anywhere tcp dpt:http redir ports 8000
I checked my Node script, which was running on port 8000, and (yes!) it was responding on port 80.
## Fumbling
During my early attempts I screwed up a bunch of times. I removed busted rules by specifying the right table, the right chain, and the right line number, like so:
[ec2-user@ip-XX-XXX-XX-X ~]$ sudo iptables -t nat -D PREROUTING 1
This removed the first line from the `PREROUTING` chain in my nat table.
## Careful, now....
I did not do this myself but throughout this process I had a very strong feeling I should be very careful not to screw up port 22, which was my only way in.
## Acknowledgements:
- [@rckenned](,
- [@jrconlin](,
- [@spullara](,
- [@frozentux]( for <>, which is a pretty definitive iptables tutorial.
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