Multiple Squid Instances and Multiple Subnets07 Mar 2016
One of my company’s client was running a Squid Proxy/Cache for two different branches with two Multiple Squid Instances bound to two different ports. Everythin was running smoothly, until he opened the following request:
I need to track down how much bandwith each branch office is using, if possible, by the proxy internal IP address that must be inside the branch’s VLAN.
To solve this problem, I now had to run not just in different ports, but also in different IPs going out different gateways. That should be fun, and ineed was.
Here is a draft of the scenario:
eth0: VLAN 10, IP 10.10.10.100/24, Gateway 10.10.10.1 eth1: VLAN 20, IP 10.10.20.100/24, Gateway 10.10.20.1
One Linux box, two gateways
The biggets difficult was to route the traffic from each subnet into their default gateways. The basic network configuration allowed just one of them, sending all traffic from both VLANs into the same destination, which only worked for one subnet.
To work this out, I needed to create custom routes with
First, create a new route policy, appending the content below in
echo "1 admin" >> /etc/iproute2/rt_tables
Here’s the configuration in
auto eth0 iface eth0 inet static address 10.10.10.100 netmask 255.255.255.0 gateway 10.10.10.1 auto eth1 iface eth1 inet static address 10.10.20.100 netmask 255.255.255.0
And the configuration used in
iproute2, you can put in
ip route add 10.10.20.0/24 dev eth1 src 10.10.20.100 table admin ip route add default via 10.10.20.1 dev eth1 table admin ip rule add from 10.10.20.100/32 table admin ip rule add to 10.10.20.100/32 table admin ip route flush cache
To test the network, I pinged to an exeternal address from each interface, like:
ping -c1 -I eth0 22.214.171.124 PING 126.96.36.199 (188.8.131.52) from 10.10.10.100 eth0: 56(84) bytes of data. 64 bytes from 184.108.40.206: icmp_seq=1 ttl=54 time=20.4 ms --- 220.127.116.11 ping statistics --- 1 packets transmitted, 1 received, 0% packet loss, time 0ms rtt min/avg/max/mdev = 20.419/20.419/20.419/0.000 ms
ping -c1 -I eth1 18.104.22.168 PING 22.214.171.124 (126.96.36.199) from 10.10.20.100 eth1: 56(84) bytes of data. 64 bytes from 188.8.131.52: icmp_seq=1 ttl=54 time=20.4 ms --- 184.108.40.206 ping statistics --- 1 packets transmitted, 1 received, 0% packet loss, time 0ms rtt min/avg/max/mdev = 20.419/20.419/20.419/0.000 ms
To get multiple Squids, I installed one from package management and one compiling the source, this way I don’t get conflict in configuration parameters or directories. If you want to compile two separated Squid instances, take a look at Squid Multiple Instances documentation.
In each Squid instance, I bound the IP address of the interface to the daemon with different ports. Also, I forced all trafic to go out by that IP, like:
http_port 10.10.10.100:3128 tcp_outgoing_address 10.10.10.100
http_port 10.10.20.100:3129 tcp_outgoing_address 10.10.20.100
We now have what we needed! All traffic from each proxy is leaving from a specifc IP. To monitor its traffic, we configured a NAT rule to a static public address on our firewall, allowing us to measure the bandwidth.
iproute2 configuration used was posted by Darien Kindlund in this blog.