netbirdio/netbird · error

TTL cannot be negative

Error message

TTL cannot be negative

What it means

Validate() rejects a negative TTL. TTL is copied verbatim from api.DNSRecordRequest.Ttl, and zero is explicitly allowed (it means "use default"), so only values below zero trigger this. There is no upper-bound check here.

Source

Thrown at management/internals/modules/zones/records/record.go:92

	switch r.Type {
	case RecordTypeA:
		if err := validateIPv4(r.Content); err != nil {
			return err
		}
	case RecordTypeAAAA:
		if err := validateIPv6(r.Content); err != nil {
			return err
		}
	case RecordTypeCNAME:
		if !domain.IsValidDomainNoWildcard(r.Content) {
			return errors.New("invalid CNAME target format")
		}
	default:
		return errors.New("invalid record type, must be A, AAAA, or CNAME")
	}

	if r.TTL < 0 {
		return errors.New("TTL cannot be negative")
	}

	return nil
}

func (r *Record) EventMeta(zoneID, zoneName string) map[string]any {
	return map[string]any{
		"name":      r.Name,
		"type":      string(r.Type),
		"content":   r.Content,
		"ttl":       r.TTL,
		"zone_id":   zoneID,
		"zone_name": zoneName,
	}
}

func validateIPv4(content string) error {
	if content == "" {

View on GitHub (pinned to 93e97f4bf1)

Solutions

1. Send a TTL of 0 (default) or a positive number of seconds.
2. If computing TTL dynamically, clamp it: ttl = max(0, computed).
3. Validate at the client boundary that the TTL field is >= 0 before issuing the request.

Example fix

// before
{"name": "api", "type": "A", "content": "192.0.2.1", "ttl": -300}
// after
{"name": "api", "type": "A", "content": "192.0.2.1", "ttl": 300}

if req.Ttl < 0 {
    return fmt.Errorf("ttl must be >= 0, got %d", req.Ttl)
}

if err := rec.Validate(); err != nil {
    return respondBadRequest(err)
}

When it happens

Trigger: A record body with "ttl": -1; a client computing TTL as a delta (e.g. expiry minus now) that goes negative when the expiry is in the past; integer underflow in generated payloads.

Common situations: Scripts deriving TTL from timestamps; form fields accepting negative numbers; negative values used as a "disable" sentinel by client convention but rejected by the server.

Related errors

• record name is required
• invalid record name format
• record type is required
• invalid CNAME target format
• invalid record type, must be A, AAAA, or CNAME

AI-assisted analysis of netbirdio/netbird@93e97f4bf1 (2026-08-16). Data as JSON: /api/errors/58e71f3efaf91c84. Report an issue: GitHub.