HTTP-01 Challenge Commands & Usage

TL;DR: Master Certbot and ACME client commands for HTTP-01 validation, from basic certbot certonly --webroot to advanced multi-domain and custom port configurations for production certificate automation.

Overview

Certificate automation relies on precise ACME client commands that handle HTTP-01 challenge validation workflows. This guide provides practical command patterns for implementing certificate issuance and renewal across different environments and platforms. Operations teams execute these commands to obtain certificates, troubleshoot validation failures, and maintain automated renewal pipelines.

Production certificate management requires understanding command options for various scenarios: single-domain certificates, multi-domain SANs, custom port configurations, and integration with different web servers. Each command pattern addresses specific deployment requirements, from simple standalone installations to complex enterprise environments with load balancers and reverse proxies.

The command reference covers Certbot as the primary ACME client, along with alternative clients for specialized use cases. Understanding these patterns helps teams implement reliable certificate automation, troubleshoot common issues, and maintain security compliance through consistent certificate lifecycle management.

Basic Certbot Commands

Standard Certificate Request

The most basic HTTP-01 challenge command uses Certbot's default configuration:

sudo certbot

This command initiates an HTTP-01 challenge but may encounter issues with CloudFront redirects that interfere with validation.

Domain-Specific Certificate Generation

For specific domain validation, use the -d flag with preferred challenge type:

certbot certonly --preferred-challenges=http -d api-dev.wieland.com

Common Issues:

Domain not accessible from DMZ server
Apache plugin requires direct server access

Multiple Domain Certificates

Generate certificates for multiple domains in a single command:

sudo certbot --preferred-challenges http -d example.org -d www.example.org -d mail.example.org

Troubleshooting: Apache configuration syntax errors can prevent certbot execution entirely.

Advanced Configuration Options

Custom Port Configuration

When operating behind NAT or using non-standard ports, specify custom HTTP-01 ports:

certbot --http-01-port 8080

Critical Note: Ensure http01_port configuration is properly set in renewal files to prevent renewal failures.

Boulder Testing Environment

For development environments using Boulder ACME server:

./certbot-auto --server http://192.168.1.10:4000/directory --apache --preferred-challenges=http --http-01-port 5002 -d test.example.com

Boulder-Specific Issues:

Uses non-standard ports 5002/5001 instead of 80/443
Port binding conflicts may occur

Testing Mode

Use staging certificates for testing without hitting rate limits:

sudo certbot --test-cert

Common Problems:

Timeout during connect (likely firewall problem)
Port 80 blocked by firewall

Web Server Integration

Apache Integration

Force HTTP-01 challenges with Apache web server integration:

sudo certbot --apache -d surgicalcenterofsandiego.com --preferred-challenges http

Validation Issues:

Invalid HTML response from challenge URL
Wrong vHost answering requests

Webroot Mode

Use webroot mode when you have an existing web server:

certbot certonly --webroot -d hostname.domain.com

Limitations:

Requires port 80 accessibility
Cannot be used for wildcard certificates

Multi-Domain Webroot Configuration

For multiple domains with webroot validation:

certbot certonly -d www.D7036.com -d www.envirotemps.com -d www.Hi-Tech.rent -d www.walkershire.net

Common Issues:

404 errors on .well-known/acme-challenge paths
Webroot path not properly configured

Legacy and Alternative Clients

LetsEncrypt-Auto (Legacy)

The original Let's Encrypt client still works for basic operations:

./letsencrypt-auto --d muxxlenetzwerk.at

It was fully deprecated since 2021 and not recommended unless for very old installs. Migrate to a newer version of the client and use recommended commands instead.

Legacy Client Issues:

Firewall blocking port 80
Multiple DNS A records causing confusion

Windows Environment

For Windows IIS environments, use letsencrypt-win-simple:

letsencrypt-win-simple automated renewal

Windows-Specific Problems:

IIS site ID mismatch during renewal
Missing site bindings

Go-ACME/Lego Client

Alternative Go-based client for HTTP-01 validation:

lego --http ...

This client performs HTTP validation on TCP port 80 with minimal configuration overhead.

PowerShell and API Integration

PowerShell ACME Module

Retrieve HTTP-01 challenges programmatically:

$challenge = Get-ACMEChallenge $global:state $global:authZ[$global:SanMap[0]] "http-01"

Integration Challenges:

Challenge file accessibility
Web server configuration

Renewal and Maintenance

Challenge Type Migration

Switch from deprecated TLS-SNI-01 to HTTP-01:

letsencrypt renew --preferred-challenges http

Migration Issues:

Old certbot versions don't recognize --preferred-challenges argument
Port 80 must be accessible

Debug Mode Renewal

Run certificate renewal with detailed debugging:

certbot run --debug --cert-name infinity-cluster.projet-horizon.fr

This helps diagnose HTTP-01 challenge failures and web server configuration issues.

Forced HTTP Challenge Preference

For mail servers and multiple domain certificates:

certbot certonly --d webmail23.marshallcnc.com -d mail23.marshallcnc.com -d mail37.defacto.in --preferred-challenges http

Issue: Default TLS-SNI-01 challenge being used instead of HTTP-01

Testing and Validation

Manual Challenge File Testing

Test challenge file accessibility before running ACME validation:

curl -I kratosinferno.fr/.well-known/acme-challenge/configcheck

Common Response Issues:

404 Not Found from nginx server
Challenge file not accessible through domain redirection

Simple Domain Validation

Test basic connectivity and challenge response:

certbot certonly -d sanchke.com

Network Issues:

Connection timeouts
Port blocking by ISP

Firewall-Friendly Testing

For environments with restrictive firewalls:

sudo certbot -d test.playtoome.com --preferred-challenges http

Requirements:

Port 80 must be accessible
Firewall rules must allow connections

Specialized Use Cases

Mac OS X Server Integration

HTTP-01 challenges on Mac OS X Server require the web server to present challenge files:

certbot with http-01 challenge