apache not accepting incoming connections from outside of localhost

Question

I've booted up a CentOS server on rackspace and executed yum install httpd'd. Then services httpd start. So, just the barebones.

I can access its IP address remotely over ssh (22) no problem, so there's no problem with the DNS or anything (I think...), but when I try to connect on port 80 (via a browser or something) I get connection refused.

From localhost, however, I can use telnet (80), or even lynx on itself and get served with no problem. From outside (my house, my school, a local coffee shop, etc...), telnet connects on 22, but not 80.

I use netstat -tulpn (<- I'm not going to lie, I don't understand the -tulpn part, but that's what the internet told me to do...) and see

tcp    0    0 :::80     :::*    LISTEN    -                    

as I believe I should. The httpd.conf says Listen 80.

I have services httpd restart'd many a time.

Honestly I have no idea what to do. There is NO way that rackspace has a firewall on incoming port 80 requests. I feel like I'm missing something stupid, but I've booted up a barebones server twice now and have done the absolute minimum to get this functioning thinking I had mucked things up with my tinkering, but neither worked.

Any help is greatly appreciated! (And sorry for the long winded post...)

Edit I was asked to post the output of iptables -L. So here it is:

Chain INPUT (policy ACCEPT) target     prot opt source               destination          ACCEPT     all  --  anywhere             anywhere            state RELATED,ESTABLISHED  ACCEPT     icmp --  anywhere             anywhere             ACCEPT     all  --  anywhere             anywhere             ACCEPT     tcp  --  anywhere             anywhere            state NEW tcp dpt:ssh  REJECT     all  --  anywhere             anywhere            reject-with icmp-host-prohibited   Chain FORWARD (policy ACCEPT) target     prot opt source               destination          REJECT     all  --  anywhere             anywhere            reject-with icmp-host-prohibited   Chain OUTPUT (policy ACCEPT) target     prot opt source               destination    

Answer 1

In case not solved yet. Your iptables say:

state RELATED,ESTABLISHED

Which means that it lets pass only connections already established... that's established by you, not by remote machines. Then you can see exceptions to this in the next rules:

state NEW tcp dpt:ssh 

Which counts only for ssh, so you should add a similar rule/line for http, which you can do like this:

state NEW tcp dpt:80 

Which you can do like this:

sudo iptables -I INPUT 4 -p tcp -m state --state NEW -m tcp --dport 80 -j ACCEPT 

(In this case I am choosing to add the new rule in the fourth line)

Remember that after editing the file you should save it like this:

sudo /etc/init.d/iptables save 

Answer 2

CentOS 7 uses firewalld by default now. But all the answers focus on iptables. So I wanted to add an answer related to firewalld.

Since firewalld is a "wrapper" for iptables, using antonio-fornie's answer still seems to work but I was unable to "save" that new rule. So I wasn't able to connect to my apache server as soon as a restart of the firewall happened. Luckily it is actually much more straightforward to make an equivalent change with firewalld commands. First check if firewalld is running:

firewall-cmd --state 

If it is running the response will simply be one line that says "running".

To allow http (port 80) connections temporarily on the public zone:

sudo firewall-cmd --zone=public --add-service=http 

The above will not be "saved", next time the firewalld service is restarted it'll go back to default rules. You should use this temporary rule to test and make sure it solves your connection issue before moving on.

To permanently allow http connections on the public zone:

sudo firewall-cmd --zone=public --permanent --add-service=http 

If you do the "permanent" command without doing the "temporary" command as well, you'll need to restart firewalld to get your new default rules (this might be different for non CentOS systems):

 sudo systemctl restart firewalld.service 

If this hasn't solved your connection issues it may be because your interface isn't in the "public zone". The following link is a great resource for learning about firewalld. It goes over in detail how to check, assign, and configure zones: https://www.digitalocean.com/community/tutorials/how-to-set-up-a-firewall-using-firewalld-on-centos-7