Problem in finding the http server through LAN

somen.chanda · 07-23-2013, 12:40 PM

Dear friends, I'm using Scientific Linux 5.2 (2.6.18-348.4.1.el5) and successfully installed Apache2.0 and PHP, started httpd. Therefore, I'm able to see the default Apache page through the browser (http://127.0.0.1/ Or http://192.168.1.2/) when looked from the localhost. I tested the setup by putting my html home page at /var/www/html/ successfully from localhost. I've a small LAN at my home which connects two windows laptops and the linux desktop with the DSL router modem (192.168.1.1). Whenever I try to look for http://192.168.1.2/ from the windows laptops it fails to connect. The router always searches for the requested ip in the outer world through the DNS. So,I edited the httpd.conf for the Listen, Allow and Deny parameters, restarted httpd but no result. Can anyone guide me what to do in this situation? I don't have a private domain setup.

Regards.
Somen.

pingu · 07-23-2013, 01:18 PM

Quote:

Originally Posted by somen.chanda

The router always searches for the requested ip in the outer world through the DNS.

This is wrong. No router should search "outer world" for a private ip.
If I understand you correctly, your DSL-modem has 2 connected interfaces, one for internet the other with ip 192.168.1.1.
And your computers are all in 192.168.1.0/24.
How do you know your modem searches outer world? If it does, with this setup it shouldn't and might be faulty - unless you manually entered a static route in the DSL-modem?
If thta was just a guess, I suggest you check the firewall on your Scientific Linux.

szboardstretcher · 07-23-2013, 01:25 PM

service iptables stop

somen.chanda · 07-24-2013, 10:06 AM

Many thanx to pingu and szboardstretcher. "/sbin/service iptables stop" did the following -
Flushing firewall rules: [ OK ]
Setting chains to policy ACCEPT: filter [ OK ]
Unloading iptables modules: [ OK ]

and now I'm able to browse my html homepage or any other html/php pages from windows machine. So it was the firewall who was stopping the incoming request. Can you please explain what is happening here? Since firewall rules are flushed, doesn't the system become vulnerable to security?

Thanx again. Regards.
Somen.

szboardstretcher · 07-24-2013, 10:14 AM

Its vulnerable now, because there is no firewall. But it proves that your firewall is the problem. For a default installation of Centos/SL6 that you want to run a webserver on, you can do this locally, DO NOT do this if you are ssh'd in, only do it LOCALLY:

Enable IPtables

Code:

service iptables start
chkconfig iptables on

Clear current IPtables policies

Code:

iptables -F
iptables -X

Put in some default rules to allow ssh and web traffic and localhost

Code:

iptables -P INPUT ACCEPT
iptables -A INPUT -i lo -j ACCEPT
iptables -A INPUT -m state --state ESTABLISHED,RELATED -j ACCEPT
iptables -A INPUT -p tcp --dport 22 -j ACCEPT
iptables -A INPUT -p tcp --dport 80 -j ACCEPT
iptables -A INPUT -p tcp --dport 443 -j ACCEPT
iptables -P INPUT DROP
iptables -P FORWARD DROP
iptables -P OUTPUT ACCEPT

Check that iptables rules worked

Code:

iptables -L -v

Save iptables if so

Code:

service iptables save

I didnt write this out of memory,. i copy and pasted a lot from http://wiki.centos.org/HowTos/Network/IPTables which I suggest you take a look at to understand what is going on here.

Happy travels.

pingu · 07-24-2013, 10:17 AM

Running no firewall means that the system becomes more vulnerable to security, that's correct.
Depending on what other firewall you have you might not need one.
The safest is to only open for http & https.
Taken from memory: "iptables -A INPUT -p tcp --dport 80 -j ACCEPT"
will open for http.

somen.chanda · 07-26-2013, 03:24 AM

Many thanks friends, the suggestions worked fine. Now I want to setup a KOHA client-server system. The server will be my SL5 machine and the windows are clients. Since KOHA client interface is an web browser application, shouldn't I expect that it would run successfully with the current setup? Regards.

Somen.