hi all,
I´m trying and playing around with some acl´s making
my exim more secure and better protected against
spammers.
Gone so far:
1) added to main:
host_lookup = !+relay_from_hosts
(!+relay_from_host to NOT make lookups on internal
senders)
2) added to acl_check_rcpt:
Deny Hosts without reverse DNS
deny message = Broken Reverse DNS no host name found
for IP address $sender_host_address
hosts = !+relay_from_hosts
!verify = reverse_host_lookup
# Check and see if some one is trying to impersonate
my server/hosts
# check and see if the HELO is a match on my domain
# would catch wananchi.com, somehost.wananchi.com, etc
# or if the HELO is my address
deny message = No you are not ME or OURS (HELO was
$sender_helo_name)
hosts = !+relay_from_hosts
log_message = Forged hostname detected in HELO:
$sender_helo_name
condition = ${if or {\
{eq{$sender_helo_name}{$interface_address}}\
{match{${lc:$sender_helo_name}}{${lc:$qualify_domain}}}}\
{yes}{no}}
# Now check the hostname.
# First check and see if the HOSTNAME is a match on my
domain
# But skip if the hostname is blank
deny message = No you are not ME or OURS (HOSTNAME
was $sender_host_name)
hosts = !+relay_from_hosts
log_message = Forged IP detected in HELO:
$sender_helo_name
condition = ${if and {\
{!eq{$sender_host_name}{}}\
{eq{$sender_host_name}{$interface_address}}}\
{yes}{no}}
# Next check and see if the HOSTNAME is my IP address
# But skip if the hostname is blank
deny message = No you are not ME or OURS (HOSTNAME
was $sender_host_name)
hosts = !+relay_from_hosts
log_message = Forged hostname detected in HELO:
$sender_helo_name
condition = ${if and {\
{!eq{$sender_host_name}{}}\
{match{${lc:$sender_host_name}}{${lc:$qualify_domain}}}}\
{yes}{no}}
So what do you think, is it ok?
But,
a)
I have still in mainlog:
"no host name found for IP address xxx.xxx.xxx.xxx
no IP address found for host HOST1 (during SMTP
connection from (HOST1) [xxx.xxx.xxx.xxx])"
for internal sender!? --> 1)
b)
how to handle "good" sender?
"no IP address found for host blahblah.com..."
a whitelist? where?
c) is it better to put the acl´s from 1) to another ,
separate acl?
hope someone can help or explain me the problematic.
I´m no exim-expert, but I want to understand the
config.
so thx in advance,
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