Problems setting up SMTP health checks with Sophos email gateway

[Gibson, Brian (IMS)]

I have a very simple configuration that I've setup to handle load balancing with my Sophos email gateway.

listen smtp_relay
bind IP:25
mode tcp
option smtpchk EHLO domain.com
balance roundrobin
server SMTPGATEWAY IP:25 check
server ALTERNATEGATEWAY IP:25 backup check

According to the logs on the Sophos appliance the health checks are sending in this format

EHLO domain.com\r\n

Which throws an error "501 Syntactically invalid EHLO argument(s)"

If I telnet to the host, and manually use EHLO domain.com it works fine, but if I do EHLO domain.com\r\n it reproduces the error.

I also tested on my Postfix and Exchange servers, and they seem to handle the \r\n just fine, but the Email gateway freaks out. I've sent a ticket in to them as well, but I was wondering if there was a way that I'm not seeing in documentation to surpress the \r\n in the health check without writing a custom check.

Thanks!

________________________________

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[Lukas Tribus]

Hello,

Post by Gibson, Brian (IMS)
EHLO domain.com\r\n
Which throws an error “501 Syntactically invalid EHLO argument(s)”
If I telnet to the host, and manually use EHLO domain.com it works fine,
but if I do EHLO domain.com\r\n it reproduces the error.

I don't know why Sophos would reject this. All (E)SMTP commands are
supposed to be terminated by \r\n (CRLF), including EHLO:

https://tools.ietf.org/html/rfc1869#section-4.2

Post by Gibson, Brian (IMS)
I was wondering if there was a way that I’m not seeing in documentation
to surpress the \r\n in the health check without writing a custom check.

No, there is not.


Regards,
Lukas

[Gibson, Brian (IMS)]

Thanks for the response, I had a feeling you were going to respond with something like that :)

I've opened a ticket with Sophos to get a resolution.

-----Original Message-----
From: ***@ltri.eu [mailto:***@ltri.eu]
Sent: Friday, September 28, 2018 7:33 AM
To: Gibson, Brian (IMS) <***@imsweb.com>
Cc: haproxy <***@formilux.org>
Subject: Re: Problems setting up SMTP health checks with Sophos email gateway

Hello,

Post by Gibson, Brian (IMS)
EHLO domain.com\r\n
Which throws an error “501 Syntactically invalid EHLO argument(s)”
If I telnet to the host, and manually use EHLO domain.com it works
fine, but if I do EHLO domain.com\r\n it reproduces the error.

I don't know why Sophos would reject this. All (E)SMTP commands are supposed to be terminated by \r\n (CRLF), including EHLO:

https://tools.ietf.org/html/rfc1869#section-4.2

Post by Gibson, Brian (IMS)
I was wondering if there was a way that I’m not seeing in
documentation to surpress the \r\n in the health check without writing a custom check.

No, there is not.


Regards,
Lukas

________________________________

Information in this e-mail may be confidential. It is intended only for the addressee(s) identified above. If you are not the addressee(s), or an employee or agent of the addressee(s), please note that any dissemination, distribution, or copying of this communication is strictly prohibited. If you have received this e-mail in error, please notify th