Sacrificial Funk

I was recently tasked with setting up a 5 server cluster for load balanced FTP and static web content serving. I found enough information on the Linux Virtual Server Project and Keepalived to get the standard failover and web protocol load balancing working well. However, when it comes to FTP and NAT, many of the online docs make comments like "Multi-port protocols are too hard!", and "I can get active ftp to work, can I somehow disable passive since it doesn't work?", and "this example config bypasses the virtual server for FTP, and isn't load balanced". In fact I found so many docs on FTP related issues, where the author only presented 10% of the solution, that putting all of them together into a working solution was dificult. So here I will attempt to gather together the complete working configuration that I finally stumbled upon.

The software packages that I used to complete this solution are:

• Red Hat Enterprise Linux 4.2 WS (should work identically with Centos 4.2)
• IPVSADM version 1.24 works properly with the current Red Hat kernel version 2.6.9-22.0.1.EL.
• Netfilter - iptables - default versions that came with RHEL 4.2
• ProFTPd version 1.2.10
• arpreset 0.2 - a package I wrote for resetting single MAC addresses on a Cisco router; helps with making the failover fast
• check_ftpget.pl - written by Jeremy Hanmer for the excellent Nagios system monitoring project.

My cluster consists of 2 load balancers (setup for active-passive failover), and 3 web/ftp servers. Here is the diagram of how they are networked together:

           VIP: (.10)     VIP: [.1]
              +-+             +-+
              |X|             |X|
              |X|-----LB1-----|X|-----Web1
              |X|  (.2)  [.2] |X|      [.11]
              |X|             |X|
   Router-----|X|             |X|-----Web2
      (.1)    |X|             |X|      [.12]
              |X|             |X|
              |X|-----LB2-----|X|-----Web3
              |X|  (.3)  [.3] |X|      [.13]
              +-+             +-+
           switch             switch

 (192.168.1.0/24)             [192.168.2.0/24]

LB1    = LVS-NAT Master Load Balancer
LB2    = LVS-NAT Backup Load Balancer
Web1-3 = Web & FTP Servers

Note:  (.1) = 192.168.1.1
       [.3] = 192.168.2.3

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