Samba: Linux Iptables Firewall Configuration

by nixCraft on October 16, 2009 · 8 comments· last updated at October 16, 2009

How do I configure iptables firewall under CentOS / Fedora / RHEL / Redhat Linux to allow access to the Samba server? How do I open TCP ports # 137, 138, 139 and 445 under Linux so that all Microsoft Windows machine can access files and printer on a Linux host?

The Samba server can be configured to allow access to certain hosts. However, iptables prevent the access over the Internet. You must allow only the systems on your network as clients of the Samba Linux server.

Iptables Open Port 137, 138, 139 and 445

Edit /etc/sysconfig/iptables file, enter:
# vi /etc/sysconfig/iptables
To allow access to 192.168.1.0/24 network only add the following before the final LOG & DROP statements:

-A RH-Firewall-1-INPUT -s 192.168.1.0/24 -m state --state NEW -p tcp --dport 137 -j ACCEPT
-A RH-Firewall-1-INPUT -s 192.168.1.0/24 -m state --state NEW -p tcp --dport 138 -j ACCEPT
-A RH-Firewall-1-INPUT -s 192.168.1.0/24 -m state --state NEW -p tcp --dport 139 -j ACCEPT
-A RH-Firewall-1-INPUT -s 192.168.1.0/24 -m state --state NEW -p tcp --dport 445 -j ACCEPT

Save and close the file.

Restart Firewall

Type the following command:
service iptables restart

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{ 8 comments… read them below or add one }

1 azlon October 17, 2009 at 1:21 pm

Great writeup! I think this may put me on the right track to figuring out my system at home.

I am running Ubuntu 9.04 and recently enabled connection sharing for my 3G USB modem. My problem is that when I enabled ICS I was no long able to access my shared folders from my Windows machines. At first I thought it had to do with my routing tables but after I read this I figured it was my iptables.

Is there a similar article for this on Ubuntu? I’m sure I can work through it and get it running but it would be nice if there were something to walk me through it (I’m very new).

2 Vivek Gite October 17, 2009 at 2:41 pm

You can use GUI tool called Firestarter (package is included with Ubuntu) is quite popular and easy to use.

OR UFW

3 Mac December 31, 2012 at 2:44 pm: Is there a UFW package for CentOS ?
Reply

4 rigidkitchen February 26, 2012 at 7:16 am

This is incorrect.

Should be:

UDP/137,138
TCP/139,445

5 Jim April 2, 2012 at 5:21 am

I cannot restart my samba after applying the iptables rules

6 rigidkitchen April 2, 2012 at 2:38 pm

Jim -

The original post is over two years old. Here are the correct firewall commands. Change 192.168.1.0/24 to your internal LAN subnet if different. After executing, use the command ‘service iptables save’, or edit /etc/sysconfig/iptables directly.

-A INPUT -s 192.168.1.0/24 -m state –state NEW -p udp –dport 137 -j ACCEPT
-A INPUT -s 192.168.1.0/24 -m state –state NEW -p udp –dport 138 -j ACCEPT
-A INPUT -s 192.168.1.0/24 -m state –state NEW -p tcp –dport 139 -j ACCEPT
-A INPUT -s 192.168.1.0/24 -m state –state NEW -p tcp –dport 445 -j ACCEPT

Additionally, firewall rules should not affect the functionality of the samba service… recheck your configuration and logs (/var/log/samba/*.log) for relevant error messages and repost any errors you see here.

7 Oldan Strange May 26, 2012 at 7:57 pm

Depending on how your browser renders fonts, the firewall rules shown above may not work. In my browser (Firefox 3.6.24 on CentOS 6.2) the characters before ‘state NEW’ and ‘dport nnn” parameters render as a single long dash (somtimes called an ‘em’ dash). In order to work correctly the long dash must be changed to 2 consecutive short dashes, then everything is fine. I discovered this doing a copy & paste of the above to modify /etc/sysconfig/iptables.

Hope this helps!

Oldan

8 Guzenkov April 18, 2013 at 11:09 am

You can put it all in one line:
iptables -I INPUT 1 -p tcp -m conntrack –ctstate=NEW -m multiport –dports 137,138,139,445 -j ACCEPT

Samba: Linux Iptables Firewall Configuration

Iptables Open Port 137, 138, 139 and 445

Restart Firewall

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