Setting Up Isolated Pod Proxy With Clash And Vpn In Kubernetes

This comprehensive guide provides detailed instructions on setting up a Kubernetes isolated pod proxy with Clash using tun mode, while ensuring restricted intranet access through NetworkPolicy. Additionally, it walks you through the process of creating a VPN, routing traffic via the VPN, and configuring Clash for an isolated proxy server.

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k8s isolated pod proxy setup

you need to disable intranet access with NetworkPolicy

find more info about intranet ranges here:

https://github.com/langgenius/dify/blob/main/docker/ssrf_proxy/squid.conf.template

http://www.squid-cache.org/Doc/config/acl/

apiVersion: networking.k8s.io/v1
kind: NetworkPolicy
metadata:
name: deny-intranet-egress
spec:
podSelector:
matchLabels:
app: hello-world
policyTypes:
- Egress
egress:
- to:
- ipBlock:
cidr: ::/0
except:
- fc00::/7
- fe80::/10
- ipBlock:
cidr: 0.0.0.0/0
except:
- 0.0.0.0/8
- 10.0.0.0/8
- 100.64.0.0/10
- 169.254.0.0/16
- 172.16.0.0/12
- 192.168.0.0/16

if you do not want to use tun routing and rely on application specific proxy adaptors, you can export environment variables at:

• /etc/profile or /etc/profile.d/proxy.sh

• ~/.bashrc

---

use clash tun mode by config.yaml

interface-name: en0 # 与 `tun.auto-detect-interface` 冲突
tun:
enable: true
stack: system # or gvisor
# dns-hijack:
#   - 8.8.8.8:53
#   - tcp://8.8.8.8:53
#   - any:53
#   - tcp://any:53
auto-route: true # manage `ip route` and `ip rules`
auto-redir: true # manage nftable REDIRECT
auto-detect-interface: true # 与 `interface-name` 冲突

ref:

https://clash.wiki/premium/tun-device.html

---

by the most you would create a tun device, then route all traffic to the device after you have installed necessary softwares.

ip tuntap add mode tun dev tun0
ip addr add 198.18.0.1/15 dev tun0
ip link set dev tun0 up
# download tun2socks
# https://github.com/xjasonlyu/tun2socks

you need to use the default gateway otherwise you will not be able to reach the dns.

the default gateway will differ from nodes. it is recommended to fetch it from ip route

for ubuntu containers you would run apt install iproute2 first

DNS_IP=8.8.8.8
GATEWAY_IP=$(ip route | grep default | grep -oE "\b([0-9]{1,3}\.){3}[0-9]{1,3}\b")
DEFAULT_ROUTE=$(ip route | grep default | sed -E 's/( metric.*)?$/ metric 100/g;')
DEFAULT_NET_DEVICE=$(ip route | grep default | grep -oP '(?<=dev )\w+')
# run with root privilege
ip route delete default
ip route add $DEFAULT_ROUTE
ip route add default dev via 198.18.0.1 tun0
ip route add $DNS_IP via $GATEWAY_IP dev $DEFAULT_NET_DEVICE

then launch tun2socks

./tun2socks -interface $DEFAULT_NET_DEVICE -device tun://tun0 -proxy <proxy_protocol>://<proxy_address>

to disable the tun network you can run:

ip route delete default dev tun0

you need to configure the dnsPolicy to None in manifest otherwise it would add the cluster dns ip to /etc/resolv.conf, slowing down the lookup process and making it very hard to change during the runtime.

not every domain shall be reached via public proxies, unless it is graranteed to not be discovered by the gfw.

the full network isolation scheme can be shown below:

internet interface
|
intranet-isolated proxy server (hysteria)
|
cluster service with clusterIP
|
isolated socks5 server with only access
to the hysteria service clusterIP and port
|
local socks5 service with clusterIP
|
isolated tun-routed pod with only access
to socks5 service clusterIP and port