Friday, 9 September 2011

Linux install and configure pound reverse proxy for Apache http / https web server

Linux install and configure pound reverse proxy for Apache http / https web server

Q. How do I install and configure pound reverse proxy for Apache web sever under Debian Linux?

A. Pound is a reverse-proxy load balancing server. It accepts requests from HTTP / HTTPS clients and distributes them to one or more Web servers. The HTTPS requests are decrypted and passed to the back-ends as plain HTTP. It will act as:
a) Server load balancer
b) Reverse proxy server
c) Apache reverse proxy etc
d) It can detects when a backend server fails or recovers, and bases its load balancing decisions on this information: if a backend server fails, it will not receive requests until it recovers
e) It can decrypts https requests to http ones
f) Rejects incorrect requests
h) It can be used in a chroot environment (security feature)

If more than one back-end server is defined, Pound chooses one of them randomly, based on defined priorities. By default, Pound keeps track of associations between clients and back-end servers (sessions).
Install Pound Software

Type the following command to install pound:
$ sudo apt-get install pound
If you are using RHEL / CentOS, grab pound rpm here and type the command:
# rpm -ivh pound*
If you are using FreeBSD, enter:
# cd /usr/ports/www/pound/ && make install clean
How it works?
Let us assume your public IP address 202.54.1.5.
Pound will run on 202.54.1.5 port 80
It will forward all incoming http requests to internal host 192.168.1.5 and 192.168.1.10 port 80 or 443
Pound keeps track of associations between clients and back-end servers
Pound configuration file
Under Debian / Ubuntu default file located at /etc/pound/pound.cfg
Under FreeBSD it is located at /usr/local/etc/pound.cfg (you need to create this file)
Under RHEL / CentOS you need to create file at /etc/pound.cfg
Sample configuration: HTTP Proxy

Forward all incoming request at 202.54.1.5 port 80 request to 192.168.1.5 Apache server running at 8080 port:
Open /etc/pound/pound.cfg file:
# vi /etc/pound/pound.cfg
To translate HTTP requests to a local internal HTTP server, enter (make sure 192.168.1.5 Apache running listing on port 8080): ListenHTTP Address 202.54.1.5 Port 80 Service BackEnd Address 192.168.1.5 Port 8080 End End End


Save and close the file. Restart pound:
# /etc/init.d/pound restart

Following example will distribute the all HTTP/HTTPS requests to two Web servers: ListenHTTP Address 202.54.1.5 Port 80 End ListenHTTPS Address 202.54.1.5 Port 443 Cert "/etc/ssl/local.server.pem" End Service BackEnd Address 192.168.1.5 Port 80 End BackEnd Address 192.168.1.6 Port 80 End End


For testing purpose you may generate self signed ssl certificate (/etc/ssl/local.server.pem), by entering the following command:
# cd /etc/ssl && openssl req -x509 -newkey rsa:1024 -keyout local.server.pem -out local.server.pem -days 365 -nodes
Pound log file

By default pound log message using syslog:
# tail -f /var/log/messages
# grep pound /var/log/messages

Sample complete configuration file

## Minimal sample pound.cfg
######################################################################
## global options:
User  "www-data"
Group  "www-data"
#RootJail "/chroot/pound"
## Logging: (goes to syslog by default)
## 0 no logging
## 1 normal
## 2 extended
## 3 Apache-style (common log format)
LogLevel 1
## check backend every X secs:
Alive  30
## use hardware-accelleration card supported by openssl(1):
#SSLEngine ""

######################################################################
## listen, redirect and ... to:
# Here is a more complex example: assume your static images (GIF/JPEG) are to be served from  a  single  back-end  192.168.0.10.  In
#       addition,  192.168.0.11  is  to  do  the  hosting for www.myserver.com with URL-based sessions, and 192.168.0.20 (a 1GHz PIII) and
#       192.168.0.21 (800Mhz Duron) are for all other requests (cookie-based sessions).  The logging will be done by the back-end servers.
#       The configuration file may look like this:
              # Main listening ports
              ListenHTTP
                  Address 202.54.1.10
                  Port    80
                  Client  10
              End
              ListenHTTPS
                  Address 202.54.1.10
                  Port    443
                  Cert    "/etc/pound/pound.pem"
                  Client  20
              End

              # Image server
              Service
                  URL ".*.(jpg|gif)"
                  BackEnd
                      Address 192.168.1.10
                      Port    80
                  End
              End
             # Virtual host www.myserver.com
              Service
                  URL         ".*sessid=.*"
                  HeadRequire "Host:.*www.nixcraft.com.*"
                  BackEnd
                      Address 192.168.1.11
                      Port    80
                  End
                  Session
                      Type    PARM
                      ID      "sessid"
                      TTL     120
                  End
              End

              # Everybody else
              Service
                  BackEnd
                      Address 192.168.1.20
                      Port    80
                      Priority 5
                  End
                  BackEnd
                      Address 192.168.1.21
                      Port    80
                      Priority 4
                  End
                  Session
                      Type    COOKIE
                      ID      "userid"
                      TTL     180
                  End
              End

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