NAME: lego - Let's Encrypt client written in Go USAGE: lego [global options] command [command options] COMMANDS: run Register an account, then create and install a certificate revoke Revoke a certificate renew Renew a certificate dnshelp Shows additional help for the '--dns' global option list Display certificates and accounts information. help, h Shows a list of commands or help for one command GLOBAL OPTIONS: --domains value, -d value [ --domains value, -d value ] Add a domain to the process. Can be specified multiple times. --server value, -s value CA hostname (and optionally :port). The server certificate must be trusted in order to avoid further modifications to the client. (default: "https://acme-v02.api.letsencrypt.org/directory") [$LEGO_SERVER] --accept-tos, -a By setting this flag to true you indicate that you accept the current Let's Encrypt terms of service. (default: false) --email value, -m value Email used for registration and recovery contact. --csr value, -c value Certificate signing request filename, if an external CSR is to be used. --eab Use External Account Binding for account registration. Requires --kid and --hmac. (default: false) [$LEGO_EAB] --kid value Key identifier from External CA. Used for External Account Binding. [$LEGO_EAB_KID] --hmac value MAC key from External CA. Should be in Base64 URL Encoding without padding format. Used for External Account Binding. [$LEGO_EAB_HMAC] --key-type value, -k value Key type to use for private keys. Supported: rsa2048, rsa3072, rsa4096, rsa8192, ec256, ec384. (default: "ec256") --filename value (deprecated) Filename of the generated certificate. --path value Directory to use for storing the data. (default: "./.lego") [$LEGO_PATH] --http Use the HTTP-01 challenge to solve challenges. Can be mixed with other types of challenges. (default: false) --http.port value Set the port and interface to use for HTTP-01 based challenges to listen on. Supported: interface:port or :port. (default: ":80") --http.proxy-header value Validate against this HTTP header when solving HTTP-01 based challenges behind a reverse proxy. (default: "Host") --http.webroot value Set the webroot folder to use for HTTP-01 based challenges to write directly to the .well-known/acme-challenge file. This disables the built-in server and expects the given directory to be publicly served with access to .well-known/acme-challenge --http.memcached-host value [ --http.memcached-host value ] Set the memcached host(s) to use for HTTP-01 based challenges. Challenges will be written to all specified hosts. --http.s3-bucket value Set the S3 bucket name to use for HTTP-01 based challenges. Challenges will be written to the S3 bucket. --tls Use the TLS-ALPN-01 challenge to solve challenges. Can be mixed with other types of challenges. (default: false) --tls.port value Set the port and interface to use for TLS-ALPN-01 based challenges to listen on. Supported: interface:port or :port. (default: ":443") --dns value Solve a DNS-01 challenge using the specified provider. Can be mixed with other types of challenges. Run 'lego dnshelp' for help on usage. --dns.disable-cp By setting this flag to true, disables the need to await propagation of the TXT record to all authoritative name servers. (default: false) --dns.resolvers value [ --dns.resolvers value ] Set the resolvers to use for performing (recursive) CNAME resolving and apex domain determination. For DNS-01 challenge verification, the authoritative DNS server is queried directly. Supported: host:port. The default is to use the system resolvers, or Google's DNS resolvers if the system's cannot be determined. --http-timeout value Set the HTTP timeout value to a specific value in seconds. (default: 0) --dns-timeout value Set the DNS timeout value to a specific value in seconds. Used only when performing authoritative name server queries. (default: 10) --pem Generate an additional .pem (base64) file by concatenating the .key and .crt files together. (default: false) --pfx Generate an additional .pfx (PKCS#12) file by concatenating the .key and .crt and issuer .crt files together. (default: false) [$LEGO_PFX] --pfx.pass value The password used to encrypt the .pfx (PCKS#12) file. (default: "changeit") [$LEGO_PFX_PASSWORD] --pfx.format value The encoding format to use when encrypting the .pfx (PCKS#12) file. Supported: RC2, DES, SHA256. (default: "RC2") [$LEGO_PFX_FORMAT] --cert.timeout value Set the certificate timeout value to a specific value in seconds. Only used when obtaining certificates. (default: 30) --user-agent value Add to the user-agent sent to the CA to identify an application embedding lego-cli --help, -h show help
NAME: lego run - Register an account, then create and install a certificate USAGE: lego run [command options] [arguments...] OPTIONS: --no-bundle Do not create a certificate bundle by adding the issuers certificate to the new certificate. (default: false) --must-staple Include the OCSP must staple TLS extension in the CSR and generated certificate. Only works if the CSR is generated by lego. (default: false) --not-before value Set the notBefore field in the certificate (RFC3339 format) --not-after value Set the notAfter field in the certificate (RFC3339 format) --preferred-chain value If the CA offers multiple certificate chains, prefer the chain with an issuer matching this Subject Common Name. If no match, the default offered chain will be used. --always-deactivate-authorizations value Force the authorizations to be relinquished even if the certificate request was successful. --run-hook value Define a hook. The hook is executed when the certificates are effectively created. --help, -h show help
NAME: lego renew - Renew a certificate USAGE: lego renew [command options] [arguments...] OPTIONS: --days value The number of days left on a certificate to renew it. (default: 30) --ari-enable Use the renewalInfo endpoint (draft-ietf-acme-ari) to check if a certificate should be renewed. (default: false) --ari-wait-to-renew-duration value The maximum duration you're willing to sleep for a renewal time returned by the renewalInfo endpoint. (default: 0s) --reuse-key Used to indicate you want to reuse your current private key for the new certificate. (default: false) --no-bundle Do not create a certificate bundle by adding the issuers certificate to the new certificate. (default: false) --must-staple Include the OCSP must staple TLS extension in the CSR and generated certificate. Only works if the CSR is generated by lego. (default: false) --not-before value Set the notBefore field in the certificate (RFC3339 format) --not-after value Set the notAfter field in the certificate (RFC3339 format) --preferred-chain value If the CA offers multiple certificate chains, prefer the chain with an issuer matching this Subject Common Name. If no match, the default offered chain will be used. --always-deactivate-authorizations value Force the authorizations to be relinquished even if the certificate request was successful. --renew-hook value Define a hook. The hook is executed only when the certificates are effectively renewed. --no-random-sleep Do not add a random sleep before the renewal. We do not recommend using this flag if you are doing your renewals in an automated way. (default: false) --help, -h show help
NAME: lego revoke - Revoke a certificate USAGE: lego revoke [command options] [arguments...] OPTIONS: --keep, -k Keep the certificates after the revocation instead of archiving them. (default: false) --reason value Identifies the reason for the certificate revocation. See https://www.rfc-editor.org/rfc/rfc5280.html#section-5.3.1. Valid values are: 0 (unspecified), 1 (keyCompromise), 2 (cACompromise), 3 (affiliationChanged), 4 (superseded), 5 (cessationOfOperation), 6 (certificateHold), 8 (removeFromCRL), 9 (privilegeWithdrawn), or 10 (aACompromise). (default: 0) --help, -h show help
NAME: lego list - Display certificates and accounts information. USAGE: lego list [command options] [arguments...] OPTIONS: --accounts, -a Display accounts. (default: false) --names, -n Display certificate common names only. (default: false) --help, -h show help
Credentials for DNS providers must be passed through environment variables. To display the documentation for a specific DNS provider, run: $ lego dnshelp -c code Supported DNS providers: acme-dns, alidns, allinkl, arvancloud, auroradns, autodns, azure, azuredns, bindman, bluecat, brandit, bunny, checkdomain, civo, clouddns, cloudflare, cloudns, cloudru, cloudxns, conoha, constellix, cpanel, derak, desec, designate, digitalocean, dnshomede, dnsimple, dnsmadeeasy, dnspod, dode, domeneshop, dreamhost, duckdns, dyn, dynu, easydns, edgedns, efficientip, epik, exec, exoscale, freemyip, gandi, gandiv5, gcloud, gcore, glesys, godaddy, googledomains, hetzner, hostingde, hosttech, httpnet, httpreq, hurricane, hyperone, ibmcloud, iij, iijdpf, infoblox, infomaniak, internetbs, inwx, ionos, ipv64, iwantmyname, joker, liara, lightsail, linode, liquidweb, loopia, luadns, mailinabox, manual, metaname, mydnsjp, mythicbeasts, namecheap, namedotcom, namesilo, nearlyfreespeech, netcup, netlify, nicmanager, nifcloud, njalla, nodion, ns1, oraclecloud, otc, ovh, pdns, plesk, porkbun, rackspace, rcodezero, regru, rfc2136, rimuhosting, route53, safedns, sakuracloud, scaleway, selectel, selectelv2, servercow, shellrent, simply, sonic, stackpath, tencentcloud, transip, ultradns, variomedia, vegadns, vercel, versio, vinyldns, vkcloud, vscale, vultr, webnames, websupport, wedos, yandex, yandex360, yandexcloud, zoneee, zonomi More information: https://go-acme.github.io/lego/dns
When using the standard --path option, all certificates and account configurations are saved to a folder .lego in the current working directory.
lego defaults to communicating with the production Let’s Encrypt ACME server. If you’d like to test something without issuing real certificates, consider using the staging endpoint instead:
lego --server=https://acme-staging-v02.api.letsencrypt.org/directory …
The CLI does not require root permissions but needs to bind to port 80 and 443 for certain challenges.
To run the CLI without sudo, you have four options:
setcap 'cap_net_bind_service=+ep' /path/to/lego (Linux only)--http.port or/and the --tls.port option and specify a custom port to bind to. In this case you have to forward port 80/443 to these custom ports (see Port Usage).--http.webroot option and specify the path to your webroot folder. In this case the challenge will be written in a file in .well-known/acme-challenge/ inside your webroot.--dns option and specify a DNS provider.By default, lego assumes it is able to bind to ports 80 and 443 to solve challenges.
If this is not possible in your environment, you can use the --http.port and --tls.port options to instruct
lego to listen on that interface:port for any incoming challenges.
If you are using either of these options, make sure you setup a proxy to redirect traffic to the chosen ports.
HTTP Port: All plaintext HTTP requests to port 80 which begin with a request path of /.well-known/acme-challenge/ for the HTTP challenge1.
TLS Port: All TLS handshakes on port 443 for the TLS-ALPN challenge.
This traffic redirection is only needed as long as lego solves challenges. As soon as you have received your certificates you can deactivate the forwarding.
When using a DNS challenge provider (via --dns <name>), Lego tries to ensure the ACME challenge token is properly setup before instructing the ACME provider to perform the validation.
This involves a few DNS queries to different servers:
Determining the DNS zone and resolving CNAMEs.
The DNS zone for a given domain is determined by the SOA record, which contains the authoritative name server for the domain and all its subdomains.
For simple domains like example.com, this is usually example.com itself.
For other domains (like fra.eu.cdn.example.com), this can get complicated, as cdn.example.com may be delegated to the CDN provider, which means for cdn.example.com must exist a different SOA record.
To find the correct zone, Lego requests the SOA record for each DNS label (starting on the leaf domain, i.e. the left-most DNS label). If there is no SOA record, Lego requests the SOA record of the parent label, then for its parent, etc., until it reaches the apex domain2. Should any DNS label on the way be a CNAME, it is resolved as per usual.
In the default configuration, Lego uses the system name servers for this, and falls back to Google’s DNS servers, should they be absent.
Verifying the challenge token.
The _acme-challenge.<yourdomain> TXT record must be correctly installed.
Lego verifies this by directly querying the authoritative name server for this record (as detected in the previous step).
Strictly speaking, this verification step is not necessary, but helps to protect your ACME account. Remember that some ACME providers impose a rate limit on certain actions (at the time of writing, Let’s Encrypt allows 300 new certificate orders per account per 3 hours).
There are also situations, where this verification step doesn’t work as expected:
_acme-challenge record might not have fully propagated to the (public) secondary servers, yet.The effect is the same: Lego determined the challenge token to be installed correctly, while Let’s Encrypt has a different view, and rejects the certificate order.
In these cases, you can instruct Lego to use a different DNS resolver, using the --dns.resolvers flag.
You should prefer one on the public internet, otherwise you might be susceptible to the same problem.
You must ensure that incoming validation requests contains the correct value for the HTTP Host header. If you operate lego behind a non-transparent reverse proxy (such as Apache or NGINX), you might need to alter the header field using --http.proxy-header X-Forwarded-Host. ↩︎
The apex domain is the domain you have registered with your domain registrar. For gTLDs (.com, .fyi) this is the 2nd level domain, but for ccTLDs, this can either be the 2nd level (.de) or 3rd level domain (.co.uk). ↩︎