Author: Renaud Allard Date: To: oliverj CC: exim-users Subject: Re: [exim] synchronization error (input sent without waiting for
greeting) - question
Oliver Howe wrote: >
> I have two smtp servers that sit behind alteon load balancers which perform health checks every 5 seconds to make sure the servers are up.
>
> but these health checks are causing a lot of messages like this to appear in the log files
>
> 2007-11-14 12:18:17 SMTP protocol violation: synchronization error (input sent without waiting for greeting): rejected connection from H=[212.57.34.221]
> 2007-11-14 12:18:22 SMTP protocol violation: synchronization error (input sent without waiting for greeting): rejected connection from H=[212.57.34.220]
> 2007-11-14 12:18:23 SMTP protocol violation: synchronization error (input sent without waiting for greeting): rejected connection from H=[212.57.34.221]
> 2007-11-14 12:18:28 SMTP protocol violation: synchronization error (input sent without waiting for greeting): rejected connection from H=[212.57.34.220]
>
>
> what is the best way to avoid such messages?
> do i need to increase the health check period on the load balancers to 30 seconds instead of 5?
>
This message is shown because your load balancers are not following RFCs. They
should wait for the HELO of your mail server before sending theirs.
To solve this, you can use control=no_enforce_sync in your connect and helo ACLs
for the IPs of your load balancers, this should work.
like:
accept
hosts = load.balancer.I.Ps
control=no_enforce_sync
Have a look at the documentation and search for "smtp_enforce_sync"
