LVS-NAT connect to real server on single network NAT

Ben Wilder ben.wilder at levexis.com
Tue Oct 17 11:59:42 BST 2006


Hi all 

Another problem if I may, relating to LVS-NAT (Single network)

OS is Fedora core 5 - kernel 2.6.15-1.2054_FC5 Ipvsadm version: 1.2.1

Network looks like the following (I am testing with one real server at the
moment)

[CIP]192.168.0.100 --> [eth0:1 VIP]192.168.0.2 (Director)[eth0 DIP]
192.168.0.1 --> [eth0 RIP]192.168.0.21

I have set things up in the following way (all machines are located on the
same switch at the moment)

Director:
1 NIC
Eth0 192.168.0.1
Eth0:1 192.168.0.2

Change net.ipv4.ip_forward = 1 in etc/sysctl.conf
Run: service iptables start
Run: iptables -Z
Run: iptables -F

Run: ipvsadm -A -t 192.168.0.2:80 -s wlc
Run: ipvsadm -a -t 192.168.0.2:80 -r 192.168.0.21:80 -m

Run: echo 0 > /proc/sys/net/ipv4/conf/all/send_redirects
Run: echo 0 > /proc/sys/net/ipv4/conf/default/send_redirects
Run: echo 0 > /proc/sys/net/ipv4/conf/eth0/send_redirects

Real server:
1 NIC
Eth0 192.168.0.21
Run: route del -net 192.168.0.0 netmask 255.255.255.0 dev eth0



Behaviour:

When i attempt to retrieve a web page from the virtual IP, everything works
fine, however as mentioned in the
how-to(http://www.austintek.com/LVS/LVS-HOWTO/HOWTO/LVS-HOWTO.LVS-NAT.html#o
ne_network) I should be able to connect directly to the services on the real
servers that are not being balanced by LVS, this is the problem! Once I have
removed that 192.168.0.0 route, I cannot connect directly to the real
servers for ssh / sftp etc. In this example I am attempting to connect from
[CIP]192.168.0.100 to [RIP]192.168.0.21 with ssh. 

Tcp dump on [RIP]192.168.0.21 using: tcpdump host 192.168.0.21 shows nothing
as I attempt to ssh in.

Should I be modifying the routing table to allow a 192.168.0.x client to
connect directly to the real server? If so how?

I have another NIC on the real server if that helps..

Any thoughts anyone?

Thanks in advance,
Ben




More information about the lvs-users mailing list