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Joseph Mack NA3T wrote:
> On Sat, 3 May 2008, Jason Ledford wrote:
>
>> I am doing a smtp cluster and after I got the lvs part figured out, smtp
>> works just fine. In your telnet session, how do you get as far as the mail
>> from and rcpt to if you aren't getting a response? If you telnet to the
>> server does it respond with a banner?
> I think there's the beginnings of the exchange in the HOWTO
I dug through it again, but couldn't find a more detailed description of
the packet flow than I already laid out.
>> I've given LVS-DR a spin and that worked fine, but the issue with that
>> is that outgoing SMTP messages (e.g. sendmail queue) would be sent from
>> the various real server public source IPs.
>
> what public IPs? For security, the only public IP on the
> realserver should be the VIP
The realservers had an unique public IP + the VIP on lo:1. But i do
suppose we could change the LVS-DR setup with iproute2 rules so that I
can get the outgoing SMTP traffic NATed over the VIP on the director, I
saw some patches about that. Anyhow, that's irrelevant for the LVS-NAT
issue I'm having.
>> When I've done this, I am getting traffic all the way: client >
>> (internet) > gateway 80.1.1.1 > VIP on director > RIP on real server >
>> back to director (ipvs?) > gateway 80.1.1.1 > (internet) > client.
>
> so the LVS is working
No, not really. Look at the twake or tcpdump logs; the realserver keeps
retransmitting the TCP packets but the client doesn't seem to tie them
to the active TCP session (regardless of what client is used, whether a
local address in the public range or any random public IP on the
internet). So it seems that something is going wrong with the TCP
session. Perhaps redundant, but I replied this in another post:
mx-node01:~# nc -p 25 -l
client:~# nc 80.1.1.10 25
When I type text in the client nc session, this text shows up on the
realserver netcat session.
When I type text in the *realserver* netcat session, it *doesn't* show
up at the client netcat session.
It is as if the data in the tcp session is one-way, e.g. data only goes
from client -> server. My TCP knowledge isn't good enough to figure out
why this happens.
> I don't really know what's going on. Since LVS is working,
> there must be something at the application layer. Is
> localhost a valid address in this context?
All nodes have just 127.0.0.1 configured on lo, if that's what you mean.
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