glider/config/examples/9.transparent_proxy_without_dnsmasq/README.md

## 9. Transparent Proxy without dnsmasq

### Glider Roles:
In this mode, glider will act as the following roles:
1. A transparent proxy server
2. A dns forwarding server
3. A ipset manager

so you don't need any dns server in your network.

#### Glider Configuration
##### glider.conf
```bash
verbose=True

# as a redir proxy
listen=redir://:1081

# as a dns forwarding server
dns=:53
dnsserver=8.8.8.8:53

# as a ipset manager
ipset=glider

# specify rule files
rules-dir=rules.d
```

##### office.rule
```bash
# add your forwarders
forward=http://forwarder1:8080,socks5://forwarder2:1080
forward=http://1.1.1.1:8080
strategy=rr
checkwebsite=www.apple.com
checkduration=30

# specify a different dns server(if need)
dnsserver=208.67.222.222:53

# specify destinations
include=office.list

domain=example1.com
domain=example2.com
# matches ip
ip=1.1.1.1
ip=2.2.2.2
# matches a ip net
cidr=192.168.100.0/24
cidr=172.16.100.0/24
```

##### office.list
```bash
# destinations list
domain=mycompany.com
domain=mycompany1.com
ip=4.4.4.4
ip=5.5.5.5
cidr=cidr=172.16.101.0/24
cidr=cidr=172.16.102.0/24
```

#### Config iptables on your linux gateway
```bash
iptables -t nat -I PREROUTING -p tcp -m set --match-set glider dst -j REDIRECT --to-ports 1081
iptables -t nat -I OUTPUT -p tcp -m set --match-set glider dst -j REDIRECT --to-ports 1081
```

#### Client DNS settings
use the linux server'ip as your dns server

#### When client requesting to access http://example1.com(in office.rule), the whole process:
- dns resolving: 
    1. client send a udp dns request to linux server, and the glider will receive the request(as it listen on default dns port :53)
    2. upstream dns server choice: glider will lookup it's rule config and find out the dns server to use for this domain(matched "example1.com" in office.rule, so 208.67.222.222:53 will be choosen)
    3. glider uses the forwarder in office.rule to ask 208.67.222.222:53 for the resolve answers
    4. glider updates it's office rule config, add the resolved ip address to it
    5. glider adds the resolved ip into ipset "glider", and return the dns answer to client
- access the destination:
    1. client send http request to the resolved ip of example1.com
    2. as the default gateway, linux server will get the request
    3. iptabes matches the ip in ipset "glider" and redirect this request to :1081(glider)
    4. glider will now get the request and find the ip in the office rule, and then choose the forwarder in office.rule to complete the request