What causes "proxy address can't be empty" in kgretzky/evilginx2?

Supply the proxy host/IP, e.g. `proxy socks5 127.0.0.1 9050 user pass`

proxy address can't be empty

Error message

proxy address can't be empty

What it means

setProxy checks that a non-empty upstream proxy address was provided when the proxy is enabled. An empty address would produce an un-routable proxy URL, so configuration is rejected. This is a required-field validation on the address argument.

Source

Thrown at core/http_proxy.go:1917

	p.ip_mtx.Lock()
	defer p.ip_mtx.Unlock()

	pl := p.getPhishletByPhishHost(hostname)
	if pl != nil {
		sid, ok := p.ip_sids[ip_addr+"-"+pl.Name]
		return sid, ok
	}
	return "", false
}

func (p *HttpProxy) setProxy(enabled bool, ptype string, address string, port int, username string, password string) error {
	if enabled {
		ptypes := []string{"http", "https", "socks5", "socks5h"}
		if !stringExists(ptype, ptypes) {
			return fmt.Errorf("invalid proxy type selected")
		}
		if len(address) == 0 {
			return fmt.Errorf("proxy address can't be empty")
		}
		if port == 0 {
			return fmt.Errorf("proxy port can't be 0")
		}

		u := url.URL{
			Scheme: ptype,
			Host:   address + ":" + strconv.Itoa(port),
		}

		if strings.HasPrefix(ptype, "http") {
			var dproxy *http_dialer.HttpTunnel
			if username != "" {
				dproxy = http_dialer.New(&u, http_dialer.WithProxyAuth(http_dialer.AuthBasic(username, password)))
			} else {
				dproxy = http_dialer.New(&u)
			}
			p.Proxy.Tr.Dial = dproxy.Dial

View on GitHub (pinned to 4c0988a1d9)

Solutions

Supply the proxy host/IP, e.g. `proxy socks5 127.0.0.1 9050 user pass`
Check that any env var or config key holding the address is actually set and non-empty
If you meant to disable the upstream proxy, pass enabled=false / `proxy off` instead of enabling with a blank address
Ensure address and port were not swapped — port alone won't fill address

Example fix

// before
p.setProxy(true, "socks5", "", 9050, "", "")
// after
p.setProxy(true, "socks5", "127.0.0.1", 9050, "", "")

Defensive patterns

Strategy: validation

Validate before calling

if enabled && len(address) == 0 {
    return fmt.Errorf("proxy address is required when proxy is enabled")
}

Type guard

func hasProxyAddress(addr string) bool {
    return strings.TrimSpace(addr) != ""
}

Try / catch

if err := proxy.setProxy(true, ptype, addr, port, user, pass); err != nil {
    if strings.Contains(err.Error(), "address can't be empty") {
        return fmt.Errorf("supply upstream proxy host, e.g. 127.0.0.1")
    }
}

Prevention

Fill in the address field right after enabling a proxy
Expand env vars and assert they are non-empty before use
Use `proxy off` instead of enabling with blank fields
Keep address and port in the documented order: type, address, port

When it happens

Trigger: Calling setProxy(true, "socks5", "", port, ...) or running the `proxy` command with the address field omitted/left blank, or a config file where the proxy address key is missing or empty string.

Common situations: Copying a proxy config example but forgetting to fill in the host, environment variable for proxy address unset and expanded to empty string, or partial paste of a proxy:port string into the wrong field.

Understand the failure class

Background: "X is required", "must be set", "cannot be empty": the missing-required-config error family, from Vertex AI project/location to WeChat keys — this error's family across 18 libraries.

Related errors

AI-assisted analysis of kgretzky/evilginx2@4c0988a1d9 (2026-09-05). Data as JSON: /api/errors/5a57f834a0967260. Report an issue: GitHub.