HTTP 407 — “Proxy Authentication Required”: Expert Customer-Service and Troubleshooting Guide

What a 407 status means

HTTP status 407 (Proxy Authentication Required) is defined in RFC 7235 (published June 2014) and signals that an HTTP proxy between client and origin server requires authentication before it will forward the request. The proxy uses the response header Proxy-Authenticate to tell the client which authentication schemes and parameters are acceptable (for example, Basic, Digest, NTLM or Negotiate/Kerberos). A canonical server response looks like: HTTP/1.1 407 Proxy Authentication Required followed by Proxy-Authenticate: Basic realm=”Proxy”.

Unlike 401 Unauthorized (which applies to the origin server), 407 is issued by an intermediary proxy. The credential the client must send is in the Proxy-Authorization request header, not Authorization. For HTTPS connections using CONNECT, the proxy can require authentication before establishing the TCP tunnel; if credentials are missing or invalid the proxy returns 407 and the TLS handshake never begins.

Common causes and diagnostics

Typical causes: a client has no proxy credentials configured, stored credentials are expired or wrong, the proxy’s authentication backend (LDAP, Active Directory, RADIUS) is unavailable, or a change to the proxy policy now requires authentication for previously open traffic. In large enterprises this often appears immediately after a policy update or proxy appliance upgrade. Public proxies (e.g., misconfigured open proxies) will also deny access with 407 when they require login.

Diagnose quickly by capturing the raw HTTP exchange. Use curl -v -x http://proxy.example.com:3128 https://example.com to see the 407 and the Proxy-Authenticate header. In browsers, check the network developer tools for the 407 response and header. On Windows check system proxy settings (Control Panel > Internet Options > Connections > LAN settings); on macOS check System Preferences > Network > Proxies; Firefox may have its own proxy settings. Tools: tcpdump, Wireshark, and curl are essential—Wireshark display filter http.response.code == 407 will show packets carrying the 407 response.

How clients should resolve a 407

First, ensure the client is configured to use the correct proxy host and port. Common proxy ports are 3128 (Squid), 8080, and 80. Next supply credentials in the proper place: browsers normally prompt and store credentials; command-line clients require explicit flags or environment variables. For curl, use: curl -v -x http://proxy.example.com:3128 -U user:password https://example.com. For programs, add Proxy-Authorization headers or use the client library’s proxy auth mechanism.

Practical code examples: in Python requests pass proxies with embedded credentials: requests.get(‘https://example.com’, proxies={‘http’:’http://user:[email protected]:3128′,’https’:’http://user:[email protected]:3128′}). In Node.js, set the environment variables HTTP_PROXY and HTTPS_PROXY, or use a global-agent package to force proxy credentials. Remember not to embed plaintext Basic credentials on unencrypted channels—use TLS between client and proxy or stronger schemes (Digest/NTLM/Kerberos).

How proxy administrators should handle 407-related customer service

When users report 407 errors, start with audit logs on the proxy appliance (timestamps, client IP, username if available). Check backend authentication services (AD, LDAP, RADIUS) availability and latency; many customer escalations trace back to LDAP bind timeouts or misbound service accounts. Review proxy policy changes and recent upgrades—frequently a policy moved groups to “authenticated only” or a certificate rotated for NTLM/Negotiate authentication.

Configuration notes for common proxies: Squid typically uses http_port 3128 and supports acl and auth_param configurations; example auth_param basic program /usr/lib/squid/basic_ncsa_auth /etc/squid/passwords. Apache acting as a forward proxy can use mod_proxy with Require valid-user; NGINX is not commonly used as a forward proxy with authentication but can be configured as a reverse proxy and perform auth_request for custom flows. Ensure logs include both access and auth results so you can correlate 407s with backend failures.

Quick troubleshooting checklist & command reference

• Capture and inspect: curl -v -x http://proxy.example.com:3128 https://example.com (shows Proxy-Authenticate header and 407 response).
• Force credentials with curl: curl -x http://proxy.example.com:3128 -U user:pass https://example.com; for NTLM use –proxy-ntlm.
• Environment vars: export HTTP_PROXY=”http://user:[email protected]:3128″ and export HTTPS_PROXY=”http://user:[email protected]:3128″ (Windows: setx HTTP_PROXY “http://user:pass@proxy:3128”).
• Python requests example: requests.get(url, proxies={‘https’: ‘http://user:[email protected]:3128’}).
• Docker: add proxy in /etc/systemd/system/docker.service.d/http-proxy.conf or in daemon.json; restart docker daemon. Example daemon.json: {“proxies”: {“default”: {“httpProxy”: “http://user:pass@proxy:3128”}}}.
• Network capture filter: Wireshark display filter http.response.code == 407 or tcp.port == 3128 to home in on proxy traffic.

Security considerations and best practices

Never transmit Basic credentials over plaintext HTTP to a proxy—use TLS between client and proxy (HTTPS for proxy endpoints) or choose stronger authentication schemes: Digest, NTLM for Windows environments, or Kerberos/Negotiate for SSO. For public-facing proxy appliances, implement rate-limiting and strong auditing. Rotate service account passwords used for backend binds and enforce least-privilege on those accounts.

For customer-facing support, document the expected behavior and provide standard commands, common error messages, and remediation steps (check proxy URL/port, check credentials, test with curl). Maintain a KB article with exact proxy hostnames, ports (e.g., proxy.company.local:3128), and the authentication methods supported. That reduces ticket churn and gets users back online faster.

Does 407 text you to pay?

Our texts never include a direct link to pay. We make outbound automated payment reminder calls. The call doesn’t ask for personal information and gives instructions to log into My Account to view and pay your bill. We send emails from [email protected], [email protected] or [email protected].

Who owns 407?

An AI Overview is not available for this searchCan’t generate an AI overview right now. Try again later.AI Overview Highway 407 is owned by 407 International Inc., which is in turn owned by Cintra Global S.E. (a subsidiary of Ferrovial S.A.) and the Canada Pension Plan Investment Board (CPP Investments) with other institutional investors. CPP Investments holds the controlling interest with a 50.1% stake, while Ferrovial holds the remaining 48.29%, making it a majority Canadian-owned entity.  Ownership Breakdown 

• CPP Investments: Owns a 50.1% controlling interest.
• Cintra Global S.E.: Owns 48.29% of the company.
• Ferrovial S.A.: The Spanish transportation firm that wholly owns Cintra Global S.E.

How the Ownership Works

• 407 International Inc. is the sole shareholder of 407 ETR. 
• 407 ETR: is responsible for the operation, management, and expansion of the Highway 407 Express Toll Route (ETR) under a 99-year concession agreement with the government of Ontario. 

AI responses may include mistakes. Learn moreAbout 407 ETR | 407 ETR, Express Toll RouteMajority Canadian-owned 407 International Inc. is the sole shareholder of 407 ETR and is owned by: Cintra Global S.E. which is a w…407 ETRThe Highway 407 Fiasco: How a Big Business Deal Turned Sour – RedditNov 4, 2024 — Since 2019, the controlling interest in the 407 has been a Crown corporation: CPP Investments. They own a 50.1% stake, Reddit · r/videos(function(){
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How do I cancel my 407 transponder?

Simply mail it back to us and sit back and relax. We’ll cover the cost to ship it, and cancel the transponder lease agreement once we receive it. Tip: Wrap your transponder in tinfoil before you put it in the envelope to avoid any invalid toll charges on its way back to us.

What is the difference between 407 and 407 ETR?

Although connected to 407 ETR, Highway 407 is a provincially owned tolled highway. To ensure a seamless experience for users of both highways, 407 ETR, provides tolling and customer services on the province’s behalf for Highway 407.

How do I call 407 customer service?

1-888-407-0407
For further details on how to pay your bill, please contact 407 ETR by telephone at 1-888-407-0407 or visit the Highway 407 website at www.on407.ca – Payments.

Does toll send text messages?

Toll operators typically don’t use text messages to collect on overdue accounts, and do not use threatening language to rush customers into action.