File size: 4,548 Bytes
fcfabd3 | 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 | #!/bin/bash
set -euo pipefail # Exit on error, undefined vars, and pipeline failures
IFS=$'\n\t' # Stricter word splitting
# 1. Extract Docker DNS info BEFORE any flushing
DOCKER_DNS_RULES=$(iptables-save -t nat | grep "127\.0\.0\.11" || true)
# Flush existing rules and delete existing ipsets
iptables -F
iptables -X
iptables -t nat -F
iptables -t nat -X
iptables -t mangle -F
iptables -t mangle -X
ipset destroy allowed-domains 2>/dev/null || true
# 2. Selectively restore ONLY internal Docker DNS resolution
if [ -n "$DOCKER_DNS_RULES" ]; then
echo "Restoring Docker DNS rules..."
iptables -t nat -N DOCKER_OUTPUT 2>/dev/null || true
iptables -t nat -N DOCKER_POSTROUTING 2>/dev/null || true
echo "$DOCKER_DNS_RULES" | xargs -L 1 iptables -t nat
else
echo "No Docker DNS rules to restore"
fi
# First allow DNS and localhost before any restrictions
# Allow outbound DNS
iptables -A OUTPUT -p udp --dport 53 -j ACCEPT
# Allow inbound DNS responses
iptables -A INPUT -p udp --sport 53 -j ACCEPT
# Allow outbound SSH
iptables -A OUTPUT -p tcp --dport 22 -j ACCEPT
# Allow inbound SSH responses
iptables -A INPUT -p tcp --sport 22 -m state --state ESTABLISHED -j ACCEPT
# Allow localhost
iptables -A INPUT -i lo -j ACCEPT
iptables -A OUTPUT -o lo -j ACCEPT
# Create ipset with CIDR support
ipset create allowed-domains hash:net
# Fetch GitHub meta information and aggregate + add their IP ranges
echo "Fetching GitHub IP ranges..."
gh_ranges=$(curl -s https://api.github.com/meta)
if [ -z "$gh_ranges" ]; then
echo "ERROR: Failed to fetch GitHub IP ranges"
exit 1
fi
if ! echo "$gh_ranges" | jq -e '.web and .api and .git' >/dev/null; then
echo "ERROR: GitHub API response missing required fields"
exit 1
fi
echo "Processing GitHub IPs..."
while read -r cidr; do
if [[ ! "$cidr" =~ ^[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}/[0-9]{1,2}$ ]]; then
echo "ERROR: Invalid CIDR range from GitHub meta: $cidr"
exit 1
fi
echo "Adding GitHub range $cidr"
ipset add allowed-domains "$cidr"
done < <(echo "$gh_ranges" | jq -r '(.web + .api + .git)[]' | aggregate -q)
# Resolve and add other allowed domains
for domain in \
"registry.npmjs.org" \
"api.anthropic.com" \
"sentry.io" \
"statsig.com" \
"marketplace.visualstudio.com" \
"vscode.blob.core.windows.net" \
"update.code.visualstudio.com"; do
echo "Resolving $domain..."
ips=$(dig +noall +answer A "$domain" | awk '$4 == "A" {print $5}')
if [ -z "$ips" ]; then
echo "ERROR: Failed to resolve $domain"
exit 1
fi
while read -r ip; do
if [[ ! "$ip" =~ ^[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}$ ]]; then
echo "ERROR: Invalid IP from DNS for $domain: $ip"
exit 1
fi
echo "Adding $ip for $domain"
ipset add allowed-domains "$ip"
done < <(echo "$ips")
done
# Get host IP from default route
HOST_IP=$(ip route | grep default | cut -d" " -f3)
if [ -z "$HOST_IP" ]; then
echo "ERROR: Failed to detect host IP"
exit 1
fi
HOST_NETWORK=$(echo "$HOST_IP" | sed "s/\.[0-9]*$/.0\/24/")
echo "Host network detected as: $HOST_NETWORK"
# Set up remaining iptables rules
iptables -A INPUT -s "$HOST_NETWORK" -j ACCEPT
iptables -A OUTPUT -d "$HOST_NETWORK" -j ACCEPT
# Set default policies to DROP first
iptables -P INPUT DROP
iptables -P FORWARD DROP
iptables -P OUTPUT DROP
# First allow established connections for already approved traffic
iptables -A INPUT -m state --state ESTABLISHED,RELATED -j ACCEPT
iptables -A OUTPUT -m state --state ESTABLISHED,RELATED -j ACCEPT
# Then allow only specific outbound traffic to allowed domains
iptables -A OUTPUT -m set --match-set allowed-domains dst -j ACCEPT
# Explicitly REJECT all other outbound traffic for immediate feedback
iptables -A OUTPUT -j REJECT --reject-with icmp-admin-prohibited
echo "Firewall configuration complete"
echo "Verifying firewall rules..."
if curl --connect-timeout 5 https://example.com >/dev/null 2>&1; then
echo "ERROR: Firewall verification failed - was able to reach https://example.com"
exit 1
else
echo "Firewall verification passed - unable to reach https://example.com as expected"
fi
# Verify GitHub API access
if ! curl --connect-timeout 5 https://api.github.com/zen >/dev/null 2>&1; then
echo "ERROR: Firewall verification failed - unable to reach https://api.github.com"
exit 1
else
echo "Firewall verification passed - able to reach https://api.github.com as expected"
fi
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