ConfigServer Community Forum

Hello, I've been attempting to enable the SMTPAUTH_RESTRICT option on our CPanel server.
It appears to be working for port 25, but causing authentication failure with port 587.

Following the instructions in /etc/csf/readme, When I add:
auth_advertise_hosts = ${if match_ip{$sender_host_address}{iplsearch;/etc/exim.smtpauth}{*}{}}

Authentication attempts via port 587 respond with this warning:
SMTP AUTH is required for message submission on port 587

Apparently given via this rule:
default_message_submission
# Reject unauthenticated relay on port 587
drop
condition = ${if eq{$interface_port}{587}{1}{0}}
message = SMTP AUTH is required for message submission on port 587

I have the follow options in csf.conf:
SMTPAUTH_RESTRICT = 1
CC_ALLOW_SMTPAUTH = US

and have included our localhost IP's in /etc/csf/csf.smtpauth :
127.0.0.0/8
"::1"
"::1/128"

I can send email through port 25, but not port 587. These tests were via remote email client.

Thanks for your time,
Jared

Has anyone else had issues like this, specifically being unable to implemented the basic settings for SMTPAUTH_RESTRICT outlined in the CSF readme, under heading 26?

Thanks,
Jared

We've been under a flood attack on SMTP for a week now, we've made some adjustments to CSF that have helped, but ultimately haven't fixed the issue. Last night LFD failed around a dozen times, as this is pretty uncommon I believe it is due to the attack.

We've blocked off some of the attack with CC_DENY but that's like using a butcher knife when all we need is a scalpel. Plus the attack is distributed, it has been coming from all over the world, and we can only block around 3 countries with CC_DENY before we start seeing that slip. Besides I really rather not block whole countries from all our other services.

That is why I have been hoping to use the SMTPAUTH_RETRICT but with the basic configuration details given in the CSF readme failing I could use a little extra help. I'm going to dig around on the EXIM configurations again to see what I am missing, but any guidance would be helpful.

Thank you for your time and patience,
Jared