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https://github.com/Start9Labs/start-os.git
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38 lines
965 B
Bash
Executable File
38 lines
965 B
Bash
Executable File
#!/bin/bash
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if [ -z "$sip" ] || [ -z "$dip" ] || [ -z "$sport" ] || [ -z "$dport" ]; then
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>&2 echo 'missing required env var'
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exit 1
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fi
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# Helper function to check if a rule exists
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nat_rule_exists() {
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iptables -t nat -C "$@" 2>/dev/null
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}
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# Helper function to add or delete a rule idempotently
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# Usage: apply_rule [add|del] <iptables args...>
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apply_nat_rule() {
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local action="$1"
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shift
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if [ "$action" = "add" ]; then
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# Only add if rule doesn't exist
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if ! rule_exists "$@"; then
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iptables -t nat -A "$@"
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fi
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elif [ "$action" = "del" ]; then
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if rule_exists "$@"; then
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iptables -t nat -D "$@"
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fi
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fi
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}
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if [ "$UNDO" = 1 ]; then
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action="del"
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else
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action="add"
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fi
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apply_nat_rule "$action" PREROUTING -p tcp -d $sip --dport $sport -j DNAT --to-destination $dip:$dport
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apply_nat_rule "$action" OUTPUT -p tcp -d $sip --dport $sport -j DNAT --to-destination $dip:$dport |