owasp-amass/amass · error

error reading the response from the WHOIS server: %v

Error message

error reading the response from the WHOIS server: %v

What it means

The bgptools WHOIS plugin wraps read errors from io.ReadAll when receiving the WHOIS response over the TCP connection. The connection was established and the request written, but reading the reply failed — typically a timeout, connection reset, or premature close while the response was in flight.

Source

Thrown at engine/plugins/whois/bgptools/plugin.go:152

	_ = bt.rlimit.Wait(ctx)
	ctx, cancel := context.WithTimeout(ctx, 10*time.Second)
	defer cancel()

	conn, err := dial(ctx, "tcp", addr)
	if err != nil {
		return nil, fmt.Errorf("failed to establish a connection with the WHOIS server: %v", err)
	}
	defer func() { _ = conn.Close() }()

	n, err := io.WriteString(conn, fmt.Sprintf("begin\n%s\nend", ipstr))
	if err != nil || n == 0 {
		return nil, fmt.Errorf("failed to send the request to the WHOIS server: %v", err)
	}

	data, err := io.ReadAll(conn)
	if err != nil {
		return nil, fmt.Errorf("error reading the response from the WHOIS server: %v", err)
	}

	record := strings.Split(string(data), "|")
	// Ensure the record contains the necessary details (AutonomousSystem and Netblock)
	if len(record) < 7 {
		return nil, errors.New("received insufficient data from the WHOIS server")
	}

	var r bgpToolsRecord
	for i, f := range record {
		field := strings.TrimSpace(f)

		switch i {
		case 0:
			num, err := strconv.Atoi(field)
			if err != nil {
				return nil, err
			}

View on GitHub (pinned to 79299dce87)

Solutions

1. Inspect the wrapped cause — timeout vs connection reset points to different fixes
2. Increase or verify the 10s timeout if responses are consistently slow on this network
3. Retry with backoff; transient resets/timeouts often succeed on a second attempt
4. Check for rate limiting from bgp.tools and slow down query volume
5. Ensure no middleboxes (VPN/proxy) are resetting long-lived TCP connections

Example fix

// before
ctx, cancel := context.WithTimeout(ctx, 10*time.Second)
// after
ctx, cancel := context.WithTimeout(ctx, 30*time.Second) // allow for slow WHOIS responses

// ensure generous deadline before reading
ctx, cancel := context.WithTimeout(context.Background(), 30*time.Second)
defer cancel()

if err != nil {
    var netErr net.Error
    if errors.As(err, &netErr) && netErr.Timeout() {
        // increase timeout and/or retry
    }
    // otherwise treat as transient reset and retry with backoff
}

When it happens

Trigger: Calling whois(ctx, ipstr) where io.ReadAll(conn) returns an error after the request was written: the 10s context/deadline expired before the server finished responding, the connection was reset mid-response, or the peer closed the socket in an error state.

Common situations: Slow or overloaded bgp.tools service exceeding the 10s deadline; rate limiting causing truncated/reset responses; flaky mobile/VPN networks dropping long-lived connections; firewalls killing connections that stay open waiting for data.

Understand the failure class

Background: Request timed out: what client-side request timeouts mean across libraries (Request timed out, TIMED_OUT, APITimeoutError) — this error's family across 39 libraries.

Related errors

• failed to establish a connection with the WHOIS server: %v
• failed to send the request to the WHOIS server: %v
• probes were not successful against the target
• failed to obtain the BGPTools IP address
• received insufficient data from the WHOIS server

AI-assisted analysis of owasp-amass/amass@79299dce87 (2026-09-06). Data as JSON: /api/errors/e6c7e332ed9c25bf. Report an issue: GitHub.