Secure Proxy Configuration(squid) for a LAN to access Internet
 

Hi
I got one linux9 server with two interface (eth0 and eth1). we also have one LAN(192.168.10.*) and one Internet connection through ISP(static ip: 203.197.96.195), i want to give Internet access to my machine which is on LAN.

for this i have installed squid on linux9 server and on my client machine i have given gatway as ip of linux9(eth0) with a simple modification in squid.conf file
##############
acl mylan access 192.168.10.0-192.168.10.20/255.255.255.0
allow http_access mylan
##############
above line may be differ a little bit. now my lan is accessing internet ..
but is it a secure way.
please provide me a good configuration for squid

thank in advance (abhishek)

Hi there,

I believe the syntax is a little off. I run squid myself and the syntax should be like this:

acl mylan src 192.168.10.0/255.255.255.0
http_access allow mylan
http_access deny all

This should allow everyone in your lan to connect to your proxy server while refusing connection attempts everywhere else. The only way that I can think of to verify the refused connections are to have a friend make an attempt to connect to your proxy.

-twantrd

hi twantrd,
thanks for your reply, you are absolutly right.

now my question is, there is too many configuration, in squid.conf file, so i am not able to analyse with option is security breach?

also when we allow http_access to mylan, is there any possibilties that outside world , can get data from mylan computers?

Hi,

These lines:

http_access allow mylan
http_access deny all

Will allow ONLY lan connection attempts to your proxy. Allow has precedence over deny therefore the allow rule will first be applied then the deny rule. Therefore outside world would not be able to connect to your proxy server at all. Also, I believe somewhere in the squid.conf there is an option for open proxy. I'm not at home at the moment so I don't know at the top of head which exact config line it is. However, you should check to see that the open proxy rule is set to off/disabled or whatever. You do not want to run an open proxy, that's for sure! :)

-twantrd

hi

Can i use squid proxy as well as firewall(iptables). if yes, than it should make my LAN more secure.
but as you said that your configuration of squid proxy is not allowing outside world, than why it is mandatory to use squid as well as firewall?

thanks for your reply(abhishek )

Hi pune,

Yes, you can use firewall with squid. You can run anything and have the firewall running as well. The reasons why you should run firewall is to block out ports to make your system more secure. The squid configuration as I have described only allows internal nodes to access the proxy but outside cannot. However, that doesn't mean that your system is secure. Think of your system like a house. Just because you have the front door locked doesn't mean there's no more entry points :)

-twantrd