By default iptables firewall stores its configuration at /etc/sysconfig/iptables file on a RHEL/CentOS 5.x/6.x. You need to edit this file and add rules to open port number. This file only available under:
- Red Hat Enterprise Linux 3 / 4 / 5 and 6
- Old Red hat Linux version
- CentOS 4/5/6
- Older version of Fedora Linux
Let us see how to open a port in the firewall on CentOS or RHEL version 5.x/6.x and 7.x including the latest version of Fedora Linux 27 or above.
How to open TCP port 80 on a RHEL/CentOS Linux
Open flle /etc/sysconfig/iptables:
# vi /etc/sysconfig/iptables
Append rule as follows:
-A RH-Firewall-1-INPUT -m state --state NEW -m tcp -p tcp --dport 80 -j ACCEPT
Save and close the file. Restart iptables:
# /etc/init.d/iptables restart
Open port TCP port # 110 on a RHEL
Append rule as follows:
-A RH-Firewall-1-INPUT -m state --state NEW -m tcp -p tcp --dport 110 -j ACCEPT
Open port 143 on a CentOS
Append rule as follows:
-A RH-Firewall-1-INPUT -m state --state NEW -m tcp -p tcp --dport 143 -j ACCEPT
Restart iptables service
Type the following command:
# service iptables restart
A note about opening a port on CentOS/RHEL 6
You can also use the iptable command as follows to open port 443:
# iptables -I INPUT -p tcp -m tcp --dport 443 -j ACCEPT
# service iptables save
A note about Red Hat Enterprise Linux 7.x and CentOS 7.x
Above commands or files won’t work on RHEL/CentOS 7.x or the latest version of Fedora Linux. To see current open ports, type:
# firewall-cmd --list-ports
Find list of zones:
# firewall-cmd --get-zones
Sample outputs:
block dmz drop external home internal public trusted work
To find about interface name use ip command:
$ ip a
Sample outputs:
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN qlen 1 link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00 inet 127.0.0.1/8 scope host lo valid_lft forever preferred_lft forever inet6 ::1/128 scope host valid_lft forever preferred_lft forever 2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1460 qdisc pfifo_fast state UP qlen 1000 link/ether 42:01:0a:80:00:04 brd ff:ff:ff:ff:ff:ff inet 10.128.0.4/32 brd 10.128.0.4 scope global dynamic eth0 valid_lft 79076sec preferred_lft 79076sec inet6 fe80::4001:aff:fe80:4/64 scope link valid_lft forever preferred_lft forever
To get info about eth0 interface:
# firewall-cmd --get-zone-of-interface=eth0
Sample outputs:
trusted
Type the following command to open TCP port 80 for Apache/httpd server:
# firewall-cmd --permanent --add-port 80/tcp
To list open port again, type:
# firewall-cmd --list-ports
Sample outputs:
1191/tcp 80/tcp 22/tcp
To open port range between 2000-3000/tcp, enter:
# firewall-cmd --permanent --add-port 2000-3000/tcp
Command to start/stop/restart firewall:
# systemctl start firewalld
# systemctl stop firewalld
# systemctl restart firewalld
# systemctl status firewalld
Sample outputs:
Verify that port is open
Run following command ss command/netstat command:
# netstat -tulpn | less
OR
# ss -tulpn | less
Make sure iptables is allowing port 80 / 110 / 143 connections by listing rules:
# iptables -L -n -v
Please refer to iptables man page for more information about iptables usage and syntax:
man iptables
man firewall-cmd
See also
- CentOS / Redhat Iptables Firewall Configuration Tutorial
- Linux: 25 Iptables Netfilter Firewall Examples For New SysAdmins
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Save and close the file. Restart iptables:# /etc/init.d/iptables restart
How to close and save a file?????
LOL, if you can’t even navigate in a *nix environment why do you even bother with iptables?
nevertheless you can do the following:
1-insert rules you want
2- press Esc
3- press :
4- wq
5- Enter
save and close a file in VI
hit ESC
type :
type x
[ESC:X]
-A RH-Firewall-1-INPUT -m state –state NEW -m tcp -p tcp –dport 587 -j ACCEPT
hi i used this code in fedora 5 to open up the port 587 in my firewall so sendmail would work using this vi command below:
vi /etc/sysconfig/iptables
then i applied the changes and restarted the firewall as you metioned above, ok poped up for all selections. did i do this ok? let me know and thanks. rich.
I wonder what is happening on my newly installed centos5.2 as all connections excepts icmp are periodically refused (up and down in un-orderly fashion)
Please advice whats wrong; action taken
#service iptables stop
#chkconfig iptables off
#chkconfig –del iptables
#mkdir /backup
#mv /etc/init.d/iptables /backup/
#mv /etc/init.d/ip6tables /backup/
#init 6
Yet the connection refuse error keep on happening time to time(more frequently that connected)
Sam,
You must be using another firewall script such as apf. Most hosting companies install something like this.
Don’t forget to make sure the ACCEPT lines are before any REJECT lines
MOVING the REJECTs to end of file or Above COMMIT Worked for me.
Helped me too. Thanks
good site, helped me a lot to restart a port in linux 5
An application that I use has an in-built Tcl webserver that uses ports 8015/8016. Is there a way to open these ports but at the same time restrict access to only selected IP addresses?
Sweet! I needed to open a port for the Sybase database server I installed on this box. Your instructions worked perfectly. Thanks for taking the time to post these instructions.
Wayne
THank you so much buddy. That really helped.
Or, you can just run “system-config-securitylevel” and do it the easy way. :)
I always hated iptables commands.
thankyou now i can open port 80 :)
I don’t seem to have a file called iptables.
When I create it in /etc/sysconfig and add one of those lines at the top, I get an error upon restart saying
“Applying iptables firewall rules: iptables-restore: line 1 failed”
Deleting that file again and restarting the service works fine. Any ideas?
Add your lines, ensuring that they appear before the final LOG and DROP lines for the RH-Firewall-1-INPUT chain. Do not add them at the top of the file.
For me, I needed to change the word RH-Firewall-1-INPUT to simply INPUT – I have CentOS 6.4. So, I ended up adding:
-A INPUT -m state –state NEW -m tcp -p tcp –dport 80 -j ACCEPT
Thanks Vivek–
I found that by using “iptables -F” followed by “service iptables save” I can generate this file. It then contians several rules – however LOG and DROP are not mentioned.
I’ve tried to add the lines in various places but get an error every time. I’m trying to accept incoming UDP traffic on a couple of ports for use with OSSEC.
the script line you advised for opening port 80 didn’t work for me!
this worked
-I INPUT -p tcp –dport 80 -j ACCEPT
Thanks this one worked for me too
Yup me too – needed to change RH-Firewall-1-INPUT to just INPUT
-A INPUT -m state –state NEW -m tcp -p tcp –dport 80 -j ACCEPT
I’ve made use of this article twice in as many weeks. Thanks!
I am Trying To Install Camfrog Server ( Linux Version ) On My Linus CentOS I can Wget And Install The App But Is Stuck After This Point Does Anyone KNow How to Install This App?
Hi iam totally a newbie to Linux, in my office i am assigned to this task which is install redhat enterprise server 5 and open up the ports 21,22 and 23 to someone else to access the box, he also needs to export the display to his machine as well, as this sounds “GREEK” to me, i need help from you guys to get this completed. pls tell me step by step what should i do?
i need to access java web service which is running on Apache in linux at port 8080 from windows.
Thanks a lot Vivek.
/etc/sysconfig/iptables-config: line 42: -A: command not found
/etc/sysconfig/iptables-config: line 43: -A: command not found
I am getting this error ????
someone from outside my network is failing to access my linux server via SSH but i can access it using Putty from within my network. Nothing has changed on my router and there is no firewall in place to block the SSH connection, how can i allow that connection, the guy can ping the server and access other ports.
This information was very useful/handy to me today (2011-07-14) , 5 years after you wrote this article (SEPTEMBER 13, 2007) ! Thank you so much VIVEK GITE. Please keep posing such useful stuff. Regards.
thnx man work fine
I edited my /etc/sysconfig/iptables file. adding in the ports I needed to open. I successfully saved and closed the file, verifying the ports were added to file by viewing the iptables file. I then went to restart it with commands listed above. I kept getting command not found. The first line of the file reads: # Firewall configuration written by system-config-securitylevel
I am running RH Linux 2.6.18-53.el5. How do I stop and start the iptables process so the additional ports will take effect?
Thanks Vivek!
Can somebody help me? im trying these methods and they dont work
iptables: Setting chains to policy ACCEPT: filter [ OK ]
iptables: Unloading modules: [ OK ]
iptables: Applying firewall rules: iptables-restore: line 10 failed
[FAILED]
[root@ sysconfig]# nano iptables
and this is what i have in the file
# Generated by iptables-save v1.4.7 on Fri Sep 16 10:50:02 2011
*filter
:INPUT ACCEPT [0:0]
:FORWARD ACCEPT [0:0]
:OUTPUT ACCEPT [13:1276]
-A INPUT -m state –state RELATED,ESTABLISHED -j ACCEPT
-A INPUT -p icmp -j ACCEPT
-A INPUT -i lo -j ACCEPT
-A INPUT -p tcp -m state –state NEW -m tcp –dport 22 -j ACCEPT
-A INOUT -p tcp -m state –state NEW -m tcp –dport 80 -j ACCEPT
-A INPUT -j REJECT –reject-with icmp-host-prohibited
-A FORWARD -j REJECT –reject-with icmp-host-prohibited
COMMIT
# Completed on Fri Sep 16 10:50:02 2011
There was a TYPO my bad but i still cant get port 80 to listen.
iptables: Flushing firewall rules: [ OK ]
iptables: Setting chains to policy ACCEPT: filter [ OK ]
iptables: Unloading modules: [ OK ]
iptables: Applying firewall rules: [ OK ]
[root@ sysconfig]# telnet localhost 80
Trying ::1…
telnet: connect to address ::1: Connection refused
Trying 127.0.0.1…
sorry for the triple post after much googling and router configurations i figured it out
hi, thanks a bunch for an informative article. you literally saved my day today.
thanks again.
Dear All,
I have installed a sever with CentOS 6.0 and then installed mySQL and PHP in it. Then i installed CPanel in it. After rebooting the system, my Login screen is disabled and i can only login via Putty software on port 22 , and can only see a console screen.
My question is:
How can i gain access to my cpanel ? i read in articles that cpanel is accessed via 2082 and 2083 ports. But both are seemed to be blocked.
Thanks in advance. Please help
Terrific info. Very helpful. Thanks.
thanks a lot. it worked perfectly
God bless
Great !
Thanks a lot !
Thank you so much dude. Both obvious and hard to troubleshoot that shit. God bless you :D
Unless I am mistaken/wrong, Fedora 20 does not appear to have the /etc/sysconfig/iptables file. Locally (Fedora 20), I find of similar appearance an /etc/sysconfig/iptables-config file; the append steps listed in this article do not appear to logically fit the syntax of the /etc/sysconfig/iptables-config file.
Will someone correct me, or may I put in a request for an updated version of this article? Many thanks!!
thanks man very useful, resolved my problem
Sir You save my life using this command
“-A RH-Firewall-1-INPUT -m state –state NEW -m tcp -p tcp –dport 143 -j ACCEPT”