On 9/22/06, siva sankar <[EMAIL PROTECTED]> wrote:
> I want to cnfigure web server in such a way that i shuld be able to send
> and receive mails from internet to my localusers.
u can do that by mail [EMAIL PROTECTED] but configure sendmail
> (2) Again i want to build firewall in such a way that,
>
> eth0- http,https,imap,smtp,pop3 ports should be activated.
open the /etc/hosts.allow there u write a line all except
> eth1- http,https ports should be activated.
> Remaining all ports should be blocked.
u can do that by using iptables, i will give an example like how to do
that for difference eth
/sbin/ipchains -A input -p tcp -s 0/0 -d 0/0 0:1023 -i eth0 -y -j REJECT
there are many ways throught which u can do tht.
Eth0 connected to internet and eth1 connected to local lan i.e. system
act as router.
Server Configuration
* Step #1 : Squid configuration so that it will act as a transparent proxy
* Step #2 : Iptables configuration
o a) Configure system as router
o b) Forward all http requests to 3128 (DNAT)
* Step #3: Run scripts and start squid service
First, Squid server installed (use up2date squid) and configured by
adding following directives to file:
# vi /etc/squid/squid.conf
Modify or add following squid directives:
httpd_accel_host virtual
httpd_accel_port 80
httpd_accel_with_proxy on
httpd_accel_uses_host_header on
acl lan src 192.168.1.1 192.168.2.0/24
http_access allow localhost
http_access allow lan
Where,
* httpd_accel_host virtual: Squid as an httpd accelerator
* httpd_accel_port 80: 80 is port you want to act as a proxy
* httpd_accel_with_proxy on: Squid act as both a local httpd
accelerator and as a proxy.
* httpd_accel_uses_host_header on: Header is turned on which is
the hostname from the URL.
* acl lan src 192.168.1.1 192.168.2.0/24: Access control list,
only allow LAN computers to use squid
* http_access allow localhost: Squid access to LAN and localhost ACL only
* http_access allow lan: ― same as above �C
Here is the complete listing of squid.conf for your reference (grep
will remove all comments and sed will remove all empty lines, thanks
to David Klein for quick hint ):
# grep -v "^#" /etc/squid/squid.conf | sed -e '/^$/d'
OR, try out sed (thanks to kotnik for small sed trick)
# cat /etc/squid/squid.conf | sed '/ *#/d; /^ *$/d'
Output:
hierarchy_stoplist cgi-bin ?
acl QUERY urlpath_regex cgi-bin \?
no_cache deny QUERY
hosts_file /etc/hosts
refresh_pattern ^ftp: 1440 20% 10080
refresh_pattern ^gopher: 1440 0% 1440
refresh_pattern . 0 20% 4320
acl all src 0.0.0.0/0.0.0.0
acl manager proto cache_object
acl localhost src 127.0.0.1/255.255.255.255
acl to_localhost dst 127.0.0.0/8
acl purge method PURGE
acl CONNECT method CONNECT
cache_mem 1024 MB
http_access allow manager localhost
http_access deny manager
http_access allow purge localhost
http_access deny purge
http_access deny !Safe_ports
http_access deny CONNECT !SSL_ports
acl lan src 192.168.1.1 192.168.2.0/24
http_access allow localhost
http_access allow lan
http_access deny all
http_reply_access allow all
icp_access allow all
visible_hostname myclient.hostname.com
httpd_accel_host virtual
httpd_accel_port 80
httpd_accel_with_proxy on
httpd_accel_uses_host_header on
coredump_dir /var/spool/squid
Iptables configuration
Next, I had added following rules to forward all http requests (coming
to port 80) to the Squid server port 3128 :
iptables -t nat -A PREROUTING -i eth1 -p tcp �Cdport 80 -j DNAT �Cto
192.168.1.1:3128
iptables -t nat -A PREROUTING -i eth0 -p tcp �Cdport 80 -j REDIRECT �Cto-port
3128
Here is complete shell script. Script first configure Linux system as
router and forwards all http request to port 3128 (Download the
fw.proxy shell script):
#!/bin/sh
# squid server IP
SQUID_SERVER="192.168.1.1″
# Interface connected to Internet
INTERNET="eth0″
# Interface connected to LAN
LAN_IN="eth1″
# Squid port
SQUID_PORT="3128″
# DO NOT MODIFY BELOW
# Clean old firewall
iptables -F
iptables -X
iptables -t nat -F
iptables -t nat -X
iptables -t mangle -F
iptables -t mangle -X
# Load IPTABLES modules for NAT and IP conntrack support
modprobe ip_conntrack
modprobe ip_conntrack_ftp
# For win xp ftp client
#modprobe ip_nat_ftp
echo 1 > /proc/sys/net/ipv4/ip_forward
# Setting default filter policy
iptables -P INPUT DROP
iptables -P OUTPUT ACCEPT
# Unlimited access to loop back
iptables -A INPUT -i lo -j ACCEPT
iptables -A OUTPUT -o lo -j ACCEPT
# Allow UDP, DNS and Passive FTP
iptables -A INPUT -i $INTERNET -m state --state ESTABLISHED,RELATED -j ACCEPT
# set this system as a router for Rest of LAN
iptables --table nat --append POSTROUTING --out-interface $INTERNET -j
MASQUERADE
iptables --append FORWARD --in-interface $LAN_IN -j ACCEPT
# unlimited access to LAN
iptables -A INPUT -i $LAN_IN -j ACCEPT
iptables -A OUTPUT -o $LAN_IN -j ACCEPT
# DNAT port 80 request comming from LAN systems to squid 3128
($SQUID_PORT) aka transparent proxy
iptables -t nat -A PREROUTING -i $LAN_IN -p tcp --dport 80 -j DNAT
--to $SQUID_SERVER:$SQUID_PORT
# if it is same system
iptables -t nat -A PREROUTING -i $INTERNET -p tcp --dport 80 -j
REDIRECT --to-port $SQUID_PORT
# DROP everything and Log it
iptables -A INPUT -j LOG
iptables -A INPUT -j DROP
Save the shell script. Execute script so that system will act as
router and forward the ports:
# chmod +x /etc/fw.proxy
# /etc/fw.proxy
# service iptables save
# chkconfig iptables on
Start or Restart the squid:
# /etc/init.d/squid restart
# chkconfig squid on
--
|Prashanth|
|B.Tech|
|RHCE|
http://munichlinux.blogspot.com
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