Linux Iptables: HowTo Block or Open HTTP/Web Service Port 80 & 443

Posted on in Categories Iptables, Linux last updated July 11, 2005

By default Apache webserver listen on port 80 (http) and port 443 (https i.e. secure http). Apache webserver uses the TCP protocol to transfer information/data between server and browser. The default Iptables configuration does not allow inbound access to the HTTP (80) and HTTPS (443) ports used by the web server. This post explains how to allow inbound and outbound access to web services under Linux.

You can edit /etc/sysconfig/iptables file under RHEL / CentOS / Fedora Linux. Add the following lines, ensuring that they appear before the final LOG and DROP lines for the RH-Firewall-1-INPUT chain to open port 80 and 443:

-A RH-Firewall-1-INPUT -m state --state NEW -p tcp --dport 80 -j ACCEPT
-A RH-Firewall-1-INPUT -m state --state NEW -p tcp --dport 443 -j ACCEPT

Finally, restart the firewall:
# service iptables restart
If you’ve your own shell script, try:

/sbin/iptables -A INPUT -m state --state NEW -p tcp --dport 80 -j ACCEPT
/sbin/iptables -A INPUT -m state --state NEW -p tcp --dport 443 -j ACCEPT

Allow incoming http/web traffic at port 80

SERVER_IP="202.54.10.20"
iptables -A INPUT -p tcp -s 0/0 --sport 1024:65535 -d $SERVER_IP --dport 80 -m state --state NEW,ESTABLISHED -j ACCEPT
iptables -A OUTPUT -p tcp -s $SERVER_IP --sport 80 -d 0/0 --dport 1024:65535 -m state --state ESTABLISHED -j ACCEPT

Allow incoming https/secure web traffic at port 443

SERVER_IP="202.54.10.20"
iptables -A INPUT -p tcp -s 0/0 --sport 1024:65535 -d $SERVER_IP --dport 443 -m state --state NEW,ESTABLISHED -j ACCEPT
iptables -A OUTPUT -p tcp -s $SERVER_IP --sport 443 -d 0/0 --dport 1024:65535 -m state --state ESTABLISHED -j ACCEPT

Allow outgoing http/web service traffic to port 80

SERVER_IP="202.54.10.20"
iptables -A OUTPUT -p tcp -s $SERVER_IP --sport 1024:65535 -d 0/0 --dport 80 -m state --state NEW,ESTABLISHED -j ACCEPT
iptables -A INPUT -p tcp -s 0/0 --sport 80 -d $SERVER_IP --dport 1024:65535 -m state --state ESTABLISHED -j ACCEPT

Allow outgoing https/secure web service traffic to port 443

SERVER_IP="202.54.10.20"
iptables -A OUTPUT -p tcp -s $SERVER_IP --sport 1024:65535 -d 0/0 --dport 443 -m state --state NEW,ESTABLISHED -j ACCEPT
iptables -A INPUT -p tcp -s 0/0 --sport 443 -d $SERVER_IP --dport 1024:65535 -m state --state ESTABLISHED -j ACCEPT

Posted by: Vivek Gite

The author is the creator of nixCraft and a seasoned sysadmin and a trainer for the Linux operating system/Unix shell scripting. He has worked with global clients and in various industries, including IT, education, defense and space research, and the nonprofit sector. Follow him on Twitter, Facebook, Google+.

13 comment

  1. How to configure Squid server with bandwidth limitation for particular network ips?
    If you response with the configuration, then it will be great help me if not also, from this site i have got lots of information. Thanks. Its a greate knowledge protal.

  2. This would be much simple and better. There is no necessary to permit the oubound traffic to be opend and can be avoided.

    # Allow incoming port 80 and 443 (http/s) traffic
    /sbin/iptables -A INPUT -p tcp –dport 80 -m state –state NEW -j ACCEPT
    /sbin/iptables -A INPUT -p tcp –dport 443 -m state –state NEW -j ACCEPT

  3. …you all forgot to mention that conntrack has to be enabled as well. Otherwise only the first packet of the connection is let in, but the “real” data is still blocked… 😉

  4. To block Gtalk, i want to set the restriction to this address:
    216.239.37.125, 72.14.253.125, 72.14.217.189 and 209.85.137.125 on ports 20, 21, 80, 443, 5222 and 5223

    How can I block these addresses to block Gtalk and https://mail.gmail.com request in transparent proxy.I am using the same script provided by nixcraft to configure Transparent proxy.

  5. I have open port 80 as you describe here but I cannot access my site from web.
    I have also configure router to forward port 80 to the pc with the apache server.
    Have you any idea what could be the problem?
    Thanks in advance.

  6. Hi,
    I am using squid proxy server in a non-transparent mode. mean everybody need to set the proxy in their browsers. These settings prevent my users to connect to any other port except 80.

    But for some reason I have to grant my IT team to access some port specific software like sqlyog, eclips etc to a particular server IP address
    To allow I do run this command.
    iptables -t nat -A POSTROUTING -s 192.168.1.48 -p tcp -m state –state NEW,ESTABLISHED -j SNAT –to-source server_public_ip
    But This command opens everything i.e gtalk, msn messenger, bit-torrents etc so I want to limit my users to make connection to required server only so that they can connect the MySQL server only using SQLYog etc.

    I have two Interface on proxy server eth0 (Public Interface) eth1 (local interface)
    local intyerface is connected to my local network only.

    Please help

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