My agentic slop goes here. Not intended for anyone else!
anil.recoil.org
1#!/bin/bash
2set -euo pipefail # Exit on error, undefined vars, and pipeline failures
3IFS=$'\n\t' # Stricter word splitting
4
5# 1. Extract Docker DNS info BEFORE any flushing
6DOCKER_DNS_RULES=$(iptables-save -t nat | grep "127\.0\.0\.11" || true)
7
8# Flush existing rules and delete existing ipsets
9iptables -F
10iptables -X
11iptables -t nat -F
12iptables -t nat -X
13iptables -t mangle -F
14iptables -t mangle -X
15ipset destroy allowed-domains 2>/dev/null || true
16
17# 2. Selectively restore ONLY internal Docker DNS resolution
18if [ -n "$DOCKER_DNS_RULES" ]; then
19 echo "Restoring Docker DNS rules..."
20 iptables -t nat -N DOCKER_OUTPUT 2>/dev/null || true
21 iptables -t nat -N DOCKER_POSTROUTING 2>/dev/null || true
22 echo "$DOCKER_DNS_RULES" | xargs -L 1 iptables -t nat
23else
24 echo "No Docker DNS rules to restore"
25fi
26
27# First allow DNS and localhost before any restrictions
28# Allow outbound DNS
29iptables -A OUTPUT -p udp --dport 53 -j ACCEPT
30# Allow inbound DNS responses
31iptables -A INPUT -p udp --sport 53 -j ACCEPT
32# Allow outbound SSH
33iptables -A OUTPUT -p tcp --dport 22 -j ACCEPT
34# Allow inbound SSH responses
35iptables -A INPUT -p tcp --sport 22 -m state --state ESTABLISHED -j ACCEPT
36# Allow localhost
37iptables -A INPUT -i lo -j ACCEPT
38iptables -A OUTPUT -o lo -j ACCEPT
39
40# Create ipset with CIDR support
41ipset create allowed-domains hash:net
42
43# Fetch GitHub meta information and aggregate + add their IP ranges
44echo "Fetching GitHub IP ranges..."
45gh_ranges=$(curl -s https://api.github.com/meta)
46if [ -z "$gh_ranges" ]; then
47 echo "ERROR: Failed to fetch GitHub IP ranges"
48 exit 1
49fi
50
51if ! echo "$gh_ranges" | jq -e '.web and .api and .git' >/dev/null; then
52 echo "ERROR: GitHub API response missing required fields"
53 exit 1
54fi
55
56echo "Processing GitHub IPs..."
57while read -r cidr; do
58 if [[ ! "$cidr" =~ ^[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}/[0-9]{1,2}$ ]]; then
59 echo "ERROR: Invalid CIDR range from GitHub meta: $cidr"
60 exit 1
61 fi
62 echo "Adding GitHub range $cidr"
63 ipset add allowed-domains "$cidr"
64done < <(echo "$gh_ranges" | jq -r '(.web + .api + .git)[]' | aggregate -q)
65
66# Resolve and add other allowed domains
67for domain in \
68 "registry.npmjs.org" \
69 "api.anthropic.com" \
70 "sentry.io" \
71 "statsig.anthropic.com" \
72 "opam.ocaml.org" \
73 "deb.debian.org" \
74 "dl.geotessera.org" \
75 "api.fastmail.com" \
76 "packages.apache.org" \
77 "statsig.com"; do
78 echo "Resolving $domain..."
79 ips=$(dig +noall +answer A "$domain" | awk '$4 == "A" {print $5}')
80 if [ -z "$ips" ]; then
81 echo "ERROR: Failed to resolve $domain"
82 exit 1
83 fi
84
85 while read -r ip; do
86 if [[ ! "$ip" =~ ^[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}$ ]]; then
87 echo "ERROR: Invalid IP from DNS for $domain: $ip"
88 exit 1
89 fi
90 echo "Adding $ip for $domain"
91 ipset add allowed-domains "$ip"
92 done < <(echo "$ips")
93done
94
95# Get host IP from default route
96HOST_IP=$(ip route | grep default | cut -d" " -f3)
97if [ -z "$HOST_IP" ]; then
98 echo "ERROR: Failed to detect host IP"
99 exit 1
100fi
101
102HOST_NETWORK=$(echo "$HOST_IP" | sed "s/\.[0-9]*$/.0\/24/")
103echo "Host network detected as: $HOST_NETWORK"
104
105# Set up remaining iptables rules
106iptables -A INPUT -s "$HOST_NETWORK" -j ACCEPT
107iptables -A OUTPUT -d "$HOST_NETWORK" -j ACCEPT
108
109# Set default policies to DROP first
110iptables -P INPUT DROP
111iptables -P FORWARD DROP
112iptables -P OUTPUT DROP
113
114# First allow established connections for already approved traffic
115iptables -A INPUT -m state --state ESTABLISHED,RELATED -j ACCEPT
116iptables -A OUTPUT -m state --state ESTABLISHED,RELATED -j ACCEPT
117
118# Then allow only specific outbound traffic to allowed domains
119iptables -A OUTPUT -m set --match-set allowed-domains dst -j ACCEPT
120
121echo "Firewall configuration complete"
122echo "Verifying firewall rules..."
123if curl --connect-timeout 5 https://example.com >/dev/null 2>&1; then
124 echo "ERROR: Firewall verification failed - was able to reach https://example.com"
125 exit 1
126else
127 echo "Firewall verification passed - unable to reach https://example.com as expected"
128fi
129
130# Verify GitHub API access
131if ! curl --connect-timeout 5 https://api.github.com/zen >/dev/null 2>&1; then
132 echo "ERROR: Firewall verification failed - unable to reach https://api.github.com"
133 exit 1
134else
135 echo "Firewall verification passed - able to reach https://api.github.com as expected"
136fi