This is a text-only version of the following page on https://raymii.org:
---
Title : haproxy: client side ssl certificates
Author : Remy van Elst
Date : 18-12-2013
URL : https://raymii.org/s/tutorials/haproxy_client_side_ssl_certificates.html
Format : Markdown/HTML
---
This tutorial shows you how to configure haproxy and client side ssl
certificates.
You need at least haproxy 1.5 dev 16 for this to work. If you want to pass the
full sha 1 hash of a certificate to a backend you need at least 1.5 dev 19.
<p class="ad"> <b>Recently I removed all Google Ads from this site due to their invasive tracking, as well as Google Analytics. Please, if you found this content useful, consider a small donation using any of the options below:</b><br><br> <a href="https://leafnode.nl">I'm developing an open source monitoring app called Leaf Node Monitoring, for windows, linux & android. Go check it out!</a><br><br> <a href="https://github.com/sponsors/RaymiiOrg/">Consider sponsoring me on Github. It means the world to me if you show your appreciation and you'll help pay the server costs.</a><br><br> <a href="https://www.digitalocean.com/?refcode=7435ae6b8212">You can also sponsor me by getting a Digital Ocean VPS. With this referral link you'll get $100 credit for 60 days. </a><br><br> </p>
Place the certificate chain file somewhere haproxy can access it and append the
following to your `bind` config line in the frontends where you want to use
client side certificates: `ca-file <path to certificate chain> verify required`.
If you want to also accept visitors without an ssl certificate change `verify
required` to `verify optional`. You might want this if you handle the
certificates in your application.
Below is an example which sends users to a different backend based on if there
is a client side certificate. It also sends users to a special error page if
there are validation errors with their client side certificate.
frontend intranet
mode http
bind 10.20.30.40:443 ssl crt /etc/haproxy/pem/server.pem ca-file /etc/haproxy/pem/client-chain.pem verify optional crt-ignore-err all crl-file /etc/haproxy/crl/haproxy.pem
use_backend ssl-error unless { ssl_c_verify 0 }
use_backend wiki if { ssl_fc_has_crt }
default_backend helpdesk
backend wiki
mode http
server wiki1 10.20.10.10:80 check
server wiki2 10.20.10.20:80 check
backend ssl-error
mode http
server helpdesk1 10.20.20.10:80 check
server helpdesk2 10.20.20.20:80 check
backend expired
mode http
option http-server-close
redirect location /certificate-expired.html if { ssl_c_verify 10 } ! { path /certificate-expired.html }
redirect location /certificate-revoked.html if { ssl_c_verify 23 } ! { path /certificate-revoked.html }
redirect location /other-certificate-error.html unless { ssl_c_verify 0 } ! { path //other-certificate-error.html }
server helpdesk3 10.20.20.30:80 check
Note that this example config also uses a CRL file to check for revocations. You
need to place that CRL file.
* If the client did not provide a certificate, haproxy uses the `helpdesk` backend.
* If the client provides a certificate, haproxy uses the `wiki` backend
* If there is an error with the client certificate, haproxy uses the `ssl-error` backend.
* If the certificate is revoked, haproxy redirects the user to the `certificate-revoked.html` page on that backend server.
* If the certificate is expired, haproxy redirects the user to the `certificate-expired.html` page on that backend server.
* If there is any other error, haproxy redirects the user to the `other-certificate-error.html` page on that backend server.
I've had issues with a DER encoded CRL file for haproxy. To convert it to pem
you can use the following command:
openssl crl -in example.crl -inform DER -outform PEM -out /etc/haproxy/crl/haproxy.crl
Combine this with a cronjob that downloads the CRL you are good to go:
*/5 * * * * wget -O /tmp/haproxy.crl http://example-ca.org/crl/example_crl.crl && openssl crl -in /tmp/example.crl -inform DER -outform PEM -out /etc/haproxy/crl/haproxy.crl
### Sending certificate details to backend application
You can also send specific details about a client certificate to your backend
application. You can then handle the verification of the certificate in your
backend application.
This example config sends all available certificate details to your backend
application as HTTP Headers:
frontend intranet
bind 10.20.30.40:443 ssl crt /etc/haproxy/pem/server.pem ca-file /etc/haproxy/pem/client-chain.pem verify required
http-request set-header X-SSL %[ssl_fc]
http-request set-header X-SSL-Client-Verify %[ssl_c_verify]
http-request set-header X-SSL-Client-SHA1 %{+Q}[ssl_c_sha1]
http-request set-header X-SSL-Client-DN %{+Q}[ssl_c_s_dn]
http-request set-header X-SSL-Client-CN %{+Q}[ssl_c_s_dn(cn)]
http-request set-header X-SSL-Issuer %{+Q}[ssl_c_i_dn]
http-request set-header X-SSL-Client-Not-Before %{+Q}[ssl_c_notbefore]
http-request set-header X-SSL-Client-Not-After %{+Q}[ssl_c_notafter]
default_backend example_backend
The `{+Q}` means that the data is quoted as a string. Otherwise it would be
binary or boolean.
In your backend the headers look like this:
X-SSL: 1
# 1 if client used a secure connection, 0 if not.
X-SSL-Client-Verify: 0
# The status code of the SSL client connection
X-SSL-Client-SHA1: "a01b894d12579d88efce97d27107f380b05f5968"
# The SHA 1 hash of the client certificate.
X-SSL-Client-DN: "/C=NL/ST=Zuid Holland/L=Rotterdam/O=Sparkling Network/CN=exampleUserCertificate/emailAddress=example@example.org"
# The full Distinguished Name of the client certificate.
X-SSL-Client-CN: "exampleUserCertificate"
# The full Common Name of the client certificate.
X-SSL-Issuer: "/C=NL/ST=Zuid Holland/L=Rotterdam/O=Sparkling Network/CN=Sparkling Intermediate Client SSL CA 2"
# The full Distinguished Name of the issuing certificate.
X-SSL-Client-Not-Before: "120101100030Z"
# Date from on which certificate is valid in format: YYMMDDhhmmss
X-SSL-Client-Not-After: "160101100030Z"
# Date from on which certificate is not valid anymore in format: YYMMDDhhmmss
### Testing it
You can use OpenSSL to test client side certificate authentication:
openssl s_client -connect 10.20.30.40:443 -cert ./client.pem -key ./client.key
### Links
* [OpenSSL CRL][2]
* [haproxy 1.5 ssl certificate data][3]
[1]: https://www.digitalocean.com/?refcode=7435ae6b8212
[2]: http://www.openssl.org/docs/apps/crl.html
[3]: http://cbonte.github.io/haproxy-dconv/configuration-1.5.html#7.3.3
---
License:
All the text on this website is free as in freedom unless stated otherwise.
This means you can use it in any way you want, you can copy it, change it
the way you like and republish it, as long as you release the (modified)
content under the same license to give others the same freedoms you've got
and place my name and a link to this site with the article as source.
This site uses Google Analytics for statistics and Google Adwords for
advertisements. You are tracked and Google knows everything about you.
Use an adblocker like ublock-origin if you don't want it.
All the code on this website is licensed under the GNU GPL v3 license
unless already licensed under a license which does not allows this form
of licensing or if another license is stated on that page / in that software:
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.
Just to be clear, the information on this website is for meant for educational
purposes and you use it at your own risk. I do not take responsibility if you
screw something up. Use common sense, do not 'rm -rf /' as root for example.
If you have any questions then do not hesitate to contact me.
See https://raymii.org/s/static/About.html for details.