Tag Archives: sni

How to get SSL with HAProxy getting rid of stunnel, stud, nginx or pound

Update: HAProxy can now handle SSL client certificate: SSL Client certificate management at application level

History

HAProxy is well know for its performance as a reverse-proxy and load-balancer and is widely deployed on web platforms where performance matters. It is sometimes even used to replace hardware load-balancers such as F5 appliances.
When the platform requires SSL, it is common to use nginx, Pound or http://www.stunnel.org/index.html. Recently, stud came in the dance with a major advantage over other software: support for HAProxy’s proxy protocol.

At HAProxy Technologies, we build our ALOHA load-balancers using HAProxy and we use stunnel as the SSL offloading software. Our clients wanted some new features on our SSL implementation we could not provide through stunnel.
By the way, you can find our stunnel patches here: http://www.haproxy.com/download/free/patches/stunnel/
An other important thing to notice, is that stunnel does not scale very well: when managing a lot en encrypted connections, stud or nginx are far much better.
That’s why we decided to implement SSL directly in HAProxy. For now, it is still quite basic: SSL offloading with SNI support and wildcard certificates, ability to encrypt traffic to servers.
But at least, the performance are here!
We’ll keep on improving it later with new features, IE: client certificate management and some fun stuff with ACLs: stay tuned!

Remember that the job was done by HAProxy Technologies engineers.

Note that if you’re using the softwares listed above for other purpose than SSL, then you may still use them. For example, nginx performs very well on static content and on dynamic using php-fpm.

SSL offloading diagram

This is pretty simple, as shown on the picture below. The client will get connected on HAProxy using SSL, HAProxy will process SSL and get connected in clear to the server:
ssl offloading diagram

HAproxy installation

cd /usr/src
wget http://haproxy.1wt.eu/download/1.5/src/devel/haproxy-1.5-dev12.tar.gz
tar xzf haproxy-1.5-dev12.tar.gz
cd haproxy-1.5-dev12/
make TARGET=linux2628 USE_STATIC_PCRE=1 USE_OPENSSL=1
sudo make PREFIX=/opt/haproxy-ssl install

HAProxy configuration for SSL offloading

First of all, you have to generate a few keys and a certificates using openssl and concatenate them in a file, the certificate first, then the key.

HAProxy configuration, very basic, for test purpose, and just to let you know which lines are very important:

defaults
 log 127.0.0.1 local0
 option tcplog

frontend ft_test
  mode http
  bind 0.0.0.0:8443 ssl crt ./haproxy.pem crt ./certs/ prefer-server-ciphers
  # other (self described) options are: [ciphers <suite>] [nosslv3] [notlsv1]
  use_backend bk_cert1 if { ssl_fc_sni cert1 } # content switching based on SNI
  use_backend bk_cert2 if { ssl_fc_sni cert2 } # content switching based on SNI
  default_backend bk_www.haproxy.com

backend bk_www.haproxy.com
 mode http
 server srvxlc 127.0.0.1:80

backend bk_cert1
  mode http
  server srv1 127.0.0.1:80

backend bk_cert2
  mode http
  server srv2 127.0.0.1:80

As you can see, HAProxy load one cert haproxy.pem which will be default one, and all the certificates from the certs dir. Actually, I have only 2 for my tests: cert1 and cert2.

Running HAProxy

First, just test the configuration is valid:

/opt/haproxy-ssl/sbin/haproxy -c -f ./hassl.cfg 
[WARNING] 247/110924 (6497) : config : missing timeouts for frontend 'ft_test'.
   | While not properly invalid, you will certainly encounter various problems
   | with such a configuration. To fix this, please ensure that all following
   | timeouts are set to a non-zero value: 'client', 'connect', 'server'.
[WARNING] 247/110924 (6497) : config : missing timeouts for backend 'bk_test'.
   | While not properly invalid, you will certainly encounter various problems
   | with such a configuration. To fix this, please ensure that all following
   | timeouts are set to a non-zero value: 'client', 'connect', 'server'.
Configuration file is valid

Don’t worry about warnings, I purposely wrote a very basic configuration.

Now, you can run HAProxy:

/opt/haproxy-ssl/sbin/haproxy  -f ./ha.cfg

Testing SSL provided by HAProxy

Check the default certificate server name:

openssl s_client -connect 127.0.0.1:8443 -servername www.haproxy.com
[...]
Certificate chain
 0 s:/CN=www.haproxy.com
   i:/CN=www.haproxy.com
[...]

HAProxy log line:

[...] ft_test bk_www.haproxy.com/srvxlc [...]

Checking cert1, loaded from ./certs/ dir:

openssl s_client -connect 127.0.0.1:8443 -servername cert1
[...]
Certificate chain
 0 s:/CN=cert1
   i:/CN=cert1
[...]

HAProxy log line:

[...] ft_test bk_cert1/srv1 [...]

Checking cert2, loaded from ./certs/ dir:

openssl s_client -connect 127.0.0.1:8443 -servername cert2
[...]
Certificate chain
 0 s:/CN=cert2
   i:/CN=cert2
[...]

HAProxy log line:

[...] ft_test bk_cert2/srv2 [...]

Checking with an unknown servername:

openssl s_client -connect 127.0.0.1:8443 -servername kemp
[...]
Certificate chain
 0 s:/CN=www.haproxy.com
   i:/CN=www.haproxy.com
[...]

HAProxy log line:

[...] ft_test bk_www.haproxy.com/srvxlc [...]

When the name is unknown, the failover is well done on the default certificate.

And voilà !!!
Since it has been released in the 1.5 branch, you can use it in production 🙂

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HOWTO SSL native in HAProxy

IMPORTANT NOTE: this article has been outdated since HAProxy-1.5-dev12 has been released (10th of September). For more information about SSL inside HAProxy. please read:


How to get SSL with HAProxy getting rid of stunnel, stud, nginx or pound

Synopsis

Since yesterday night (FR time), HAProxy can support SSL offloading. It can even crypt traffic to a downstream server.
We’ll see later all the fun we could have with these nice features and the goodness it could bring in term of architecture. Today, I’ll just focus on how to install and configure HAProxy to offload SSL processing from your servers.

It’s important to notice that in order to be able to manage SSL connections, a huge rework of connection management has been done in HAProxy. Despite the long time spent on testing, there might still remain some bugs.
So we ask anybody who tests the procedure below to report bugs to HAProxy mailing list.

Note as well that the job was done by HAProxy Technologies engineers, who already improved stunnel and stud.

SSL offloading diagram

This is pretty simple, as shown on the picture below. The client will get connected on HAProxy using SSL, HAProxy will process SSL and get connected in clear to the server:
ssl offloading diagram

HAproxy installation

cd /usr/src
wget http://haproxy.1wt.eu/download/1.5/src/snapshot/haproxy-ss-20120905.tar.gz
tar xzf haproxy-ss-20120905.tar.gz
cd haproxy-ss-20120905/
make TARGET=linux2628 USE_STATIC_PCRE=1 USE_OPENSSL=1
sudo make PREFIX=/opt/haproxy-ssl install

HAProxy configuration for SSL offloading


First of all, you have to generate a key and a certificate using openssl and concatenate them in a file, the certificate first, then the key.
Here is mine, just copy/paste it in a file for your tests:

-----BEGIN CERTIFICATE-----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-----END CERTIFICATE-----
-----BEGIN RSA PRIVATE KEY-----
MIICXgIBAAKBgQDFxSTUwX5RD4AL2Ya5t5PAaNjcwPa3Km40uaPKSHlU8AMydxC1
wB4L0k3Ms9uh98R+kIJS+TxdfDaYxk/GdDYI1CMm4TM+BLHGAVA2DeNf2hBhBRKb
TAgxCxXwORJQSB/B+1r0/ZiQ2ig5Jzr8xGHz+tBsHYZ+t+RmjZPQFjnlewIDAQAB
AoGBALUeVhuuVLOB4X94qGSe1eZpXunUol2esy0AMhtIAi4iXJsz5Y69sgabg/qL
YQJVOZO7Xk8EyB7JaerB+z9BIFWbZwS9HirqR/sKjjbhu/rAQDgjVWw2Y9sjPhEr
CEAvqmQskT4mY+RW4qz2k8pe4HKq8NAFwbe8iNP7AySP3K4BAkEA4ZPBagtlJzrU
7Tw4BvQJhBmvNYEFviMScipHBlpwzfW+79xvZhTxtsSBHAM9KLbqO33VmJ3C/L/t
xukW8SO6ewJBAOBxU0TfS0EzcRQJ4sn78G6hTjjLwJM2q4xuSwLQDVaWwtXDI6HE
jb7HePaGBGnOrlXxEOFQZCVdDaLhX0zcEQECQQDHcvc+phioGRKPOAFp1HhdfsA2
FIBZX3U90DfAXFMFKFXMiyFMJxSZPyHQ/OQkjaaJN3eWW1c+Vw0MJKgOSkLlAkEA
h8xpqoFEgkXCxHIa00VpuzZEIt89PJVWhJhzMFd7yolbh4UTeRx4+xasHNUHtJFG
MF+0a+99OJIt3wBn7hQ1AQJACScT3p6zJ4llm59xTPeOYpSXyllR4GMilsGIRNzT
RGYxcvqR775RkAgE+5DHmAkswX7TBaxcO6+C1+LJEwFRxw==
-----END RSA PRIVATE KEY-----

Now, HAProxy configuration, very basic, for test purpose, and just to let you know which lines are very important:

frontend ft_test
  mode http
  bind 0.0.0.0:8443 ssl crt ./haproxy.pem  # basic conf require only 1 keyword
  # other (self described) options are: [ciphers <suite>] [nosslv3] [notlsv1]
  default_backend bk_test

backend bk_test
  mode http
  server srv1 127.0.0.1:80

Running HAProxy


First, just test the configuration is valid:

/opt/haproxy-ssl/sbin/haproxy -c -f ./ha.cfg 
[WARNING] 247/110924 (6497) : config : missing timeouts for frontend 'ft_test'.
   | While not properly invalid, you will certainly encounter various problems
   | with such a configuration. To fix this, please ensure that all following
   | timeouts are set to a non-zero value: 'client', 'connect', 'server'.
[WARNING] 247/110924 (6497) : config : missing timeouts for backend 'bk_test'.
   | While not properly invalid, you will certainly encounter various problems
   | with such a configuration. To fix this, please ensure that all following
   | timeouts are set to a non-zero value: 'client', 'connect', 'server'.
Configuration file is valid

Don’t worry about warnings, I purposely wrote a very basic configuration.

Now, you can run HAProxy:

/opt/haproxy-ssl/sbin/haproxy  -f ./ha.cfg

Testing SSL provided by HAProxy


Use curl, with “–insecure” option if your certificate is self-signed, like mine:

curl --noproxy * -D - --insecure https://127.0.0.1:8443/index.html
HTTP/1.1 200 OK
Date: Tue, 04 Sep 2012 09:13:55 GMT
Server: Apache/2.2.16 (Debian)
Last-Modified: Tue, 04 Sep 2012 09:10:01 GMT
ETag: "a35d1-e-4c8dc9f7d6c40"
Accept-Ranges: bytes
Content-Length: 14
Vary: Accept-Encoding
Content-Type: text/html

Welcome page.

Check SSL parameters with openssl in client mode:

openssl s_client -connect 127.0.0.1:8443
CONNECTED(00000003)
depth=0 /CN=www.exceliance.fr
verify error:num=18:self signed certificate
verify return:1
depth=0 /CN=www.exceliance.fr
verify return:1
---
Certificate chain
 0 s:/CN=www.exceliance.fr
   i:/CN=www.exceliance.fr
---
Server certificate
-----BEGIN CERTIFICATE-----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-----END CERTIFICATE-----
subject=/CN=www.exceliance.fr
issuer=/CN=www.exceliance.fr
---
No client certificate CA names sent
---
SSL handshake has read 604 bytes and written 319 bytes
---
New, TLSv1/SSLv3, Cipher is AES256-SHA
Server public key is 1024 bit
Secure Renegotiation IS supported
Compression: NONE
Expansion: NONE
SSL-Session:
    Protocol  : TLSv1
    Cipher    : AES256-SHA
    Session-ID: CF9B7BFF64DE0B332CE9A76896EC1C59C941340D6913612286113FA1F7E09E88
    Session-ID-ctx: 
    Master-Key: C6893078E49626DAF329C61774BA5A35E0264818E0D76542F25BB958584B835154402E02F9B722DD94C56B14EBB14D46
    Key-Arg   : None
    Start Time: 1346750742
    Timeout   : 300 (sec)
    Verify return code: 18 (self signed certificate)
---
GET / HTTP/1.0

HTTP/1.1 200 OK
Date: Tue, 04 Sep 2012 09:26:44 GMT
Server: Apache/2.2.16 (Debian)
Last-Modified: Tue, 04 Sep 2012 09:10:01 GMT
ETag: "a35d1-e-4c8dc9f7d6c40"
Accept-Ranges: bytes
Content-Length: 14
Vary: Accept-Encoding
Connection: close
Content-Type: text/html

Welcome page.
closed

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Enhanced SSL load-balancing with Server Name Indication (SNI) TLS extension

Synopsis

Some time ago, we wrote an article which explained how to load-balance SSL services, maintaining affinity using the SSLID.
The main limitation of this kind of architecture is that you must dedicate a public IP address and port per service.
If you’re hosting web or mail services, you could run out of public IP address quickly.

TLS protocol has been extended in 2003, RFC 3546, by an extension called SNI: Server Name Indication, which allows a client to announce in clear the server name it is contacting.

NOTE: two RFC have obsoleted the one above, the latest one is RFC 6066

The Aloha Load-balancer can use this information to choose a backend or a server.
This allows people to share a single VIP for several services.

Of course, we can use SNI switching with SSLID affinity to build a smart and reliable SSL load-balanced platform.

NOTE: Server Name information is sent with each SSL Handshake, whether you’re establishing a new session or you’re resuming an old one.

SNI is independent from the protocol used at layer 7. So basically, it will work with IMAP, HTTP, SMTP, POP, etc…

Limitation

Bear in mind, that in 2012, not all clients are compatible with SNI.
Concerning web browsers, a few of used in 2012 them are still not compatible with this TLS protocol extension.

We strongly recommend you to read the Wikipedia Server Name Indication page which lists all the limitation of this extension.

  • Only HAProxy nightly snapshots from 8th of April are compatible (with no bug knows) with it.
  • Concerning Aloha, it will be available by Aloha Load-balancer firmware 5.0.2.

Diagram

The picture below shows a platform with a single VIP which host services for 2 applications:
sni_loadbalancing

We can use SNI information to choose a backend, then, inside a backend, we can use SSLID affinity.

Configuration

Choose a backend using SNI TLS extension


The configuration below matches names provided by the SNI extention and choose a farm based on it.
In the farm, it provides SSLID affinity.
If no SNI extention is sent, then we redirect the user to a server farm which can be used to tell the user to upgrade its software.

# Adjust the timeout to your needs
defaults
  timeout client 30s
  timeout server 30s
  timeout connect 5s

# Single VIP with sni content switching
frontend ft_ssl_vip
  bind 10.0.0.10:443
  mode tcp

  tcp-request inspect-delay 5s
  tcp-request content accept if { req_ssl_hello_type 1 }
  
  acl application_1 req_ssl_sni -i application1.domain.com
  acl application_2 req_ssl_sni -i application2.domain.com

  use_backend bk_ssl_application_1 if application_1
  use_backend bk_ssl_application_2 if application_2

  default_backend bk_ssl_default

# Application 1 farm description
backend bk_ssl_application_1
  mode tcp
  balance roundrobin

  # maximum SSL session ID length is 32 bytes.
  stick-table type binary len 32 size 30k expire 30m

  acl clienthello req_ssl_hello_type 1
  acl serverhello rep_ssl_hello_type 2

  # use tcp content accepts to detects ssl client and server hello.
  tcp-request inspect-delay 5s
  tcp-request content accept if clienthello

  # no timeout on response inspect delay by default.
  tcp-response content accept if serverhello

  stick on payload_lv(43,1) if clienthello

  # Learn on response if server hello.
  stick store-response payload_lv(43,1) if serverhello

  option ssl-hello-chk
  server server1 192.168.1.1:443 check
  server server2 192.168.1.2:443 check

# Application 2 farm description
backend bk_ssl_application_2
  mode tcp
  balance roundrobin

  # maximum SSL session ID length is 32 bytes.
  stick-table type binary len 32 size 30k expire 30m

  acl clienthello req_ssl_hello_type 1
  acl serverhello rep_ssl_hello_type 2

  # use tcp content accepts to detects ssl client and server hello.
  tcp-request inspect-delay 5s
  tcp-request content accept if clienthello

  # no timeout on response inspect delay by default.
  tcp-response content accept if serverhello

  stick on payload_lv(43,1) if clienthello

  # Learn on response if server hello.
  stick store-response payload_lv(43,1) if serverhello

  option ssl-hello-chk
  server server1 192.168.2.1:443 check
  server server2 192.168.2.2:443 check

# Sorry backend which should invite the user to update its client
backend bk_ssl_default
  mode tcp
  balance roundrobin
  
  # maximum SSL session ID length is 32 bytes.
  stick-table type binary len 32 size 30k expire 30m

  acl clienthello req_ssl_hello_type 1
  acl serverhello rep_ssl_hello_type 2

  # use tcp content accepts to detects ssl client and server hello.
  tcp-request inspect-delay 5s
  tcp-request content accept if clienthello

  # no timeout on response inspect delay by default.
  tcp-response content accept if serverhello

  stick on payload_lv(43,1) if clienthello

  # Learn on response if server hello.
  stick store-response payload_lv(43,1) if serverhello

  option ssl-hello-chk
  server server1 10.0.0.11:443 check
  server server2 10.0.0.12:443 check

Choose a server using SNI: aka SSL routing


The configuration below matches names provided by the SNI extention and choose a server based on it.
If no SNI is provided or we can’t find the expected name, then the traffic is forwarded to server3 which can be used to tell the user to upgrade its software.

# Adjust the timeout to your needs
defaults
  timeout client 30s
  timeout server 30s
  timeout connect 5s

# Single VIP 
frontend ft_ssl_vip
  bind 10.0.0.10:443
  mode tcp

  tcp-request inspect-delay 5s
  tcp-request content accept if { req_ssl_hello_type 1 }

  default_backend bk_ssl_default

# Using SNI to take routing decision
backend bk_ssl_default
  mode tcp

  acl application_1 req_ssl_sni -i application1.domain.com
  acl application_2 req_ssl_sni -i application2.domain.com

  use-server server1 if application_1
  use-server server2 if application_2
  use-server server3 if !application_1 !application_2

  option ssl-hello-chk
  server server1 10.0.0.11:443 check
  server server2 10.0.0.12:443 check
  server server3 10.0.0.13:443 check

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