Hi Udera,
I believe some configuration like
deny
condition = ${if isip{$sender_helo_name}}
!hosts = PROBLEMFAELLE_HELO
message = Access denied - Invalid HELO name (See RFC2821 4.1.3)
# Neither an address literal nor something containing dots
deny
!hosts = PROBLEMFAELLE_HELO
condition = ${if match{$sender_helo_name}{\N^\[\N}{no}{yes}}
condition = ${if match{$sender_helo_name}{\N\.\N}{no}{yes}}
message = Access denied - Invalid HELO name (See RFC2821 4.1.1.1)
warn
condition = ${if match{$sender_helo_name}{\N\.$\N}}
log_message = HELO ending with dot
set acl_c_greylisting = 1
warn
condition = ${if match{$sender_helo_name}{\N\.\.\N}}
log_message = HELO contains two subsequent dots.
set acl_c_greylisting = 1
warn
condition = ${if match{$sender_helo_name}{$primary_hostname}}
log_message = HELO is MY primary hostname
set acl_c_greylisting = 1
is quite common.
But keep in mind: if you simply deny in HELO will simply signal a deny
to the client but if the client simply ingores your response and starts
sending a message anyway, it will be accepted by exim.
There was a discussion in January about that issue, have a look at the
discussion in the archive ("exim still accepting email after 550 from
acl_check_helo").
On 20.04.2016 09:47, Udera Udera wrote:
> Dear list,
>
> I tried to implement a ACL-helo-check from the exim-wiki on github:
> https://github.com/Exim/exim/wiki/AclHeloTricks#helo-is-faked-interface-address
>
> drop message = Bad helo name
> condition = ${if \
> and{ \
> {isip {$sender_helo_name}} \
> {match_ip{$sender_helo_name}{@[]}} \
> }{yes}{no} \
> }
>
> But it doesn't work. Just suppose my server ip is 10.0.0.1.
>
> I want to reject servers that use my ip address as their EHLO, that would
> be:
> EHLO [10.0.0.1]
>
> Unfortunately, that does not work because
>
> isip {$sender_helo_name}
>
>
> isn't true. If the plain ip address is used, this would work but plain ip
> addresses are not allowed (and already covered by:
> https://github.com/Exim/exim/wiki/AclHeloTricks#helo-is-an-ip-address).
>
> I tried to get rid of the brackets but I didn't get the syntax right and
> I'm not sure if this is the way to go:
> drop condition = ${if
> match{${substr{1}{${length{$sender_helo_name}-2}}{$sender_helo_name}}}{@
> []}{yes}{no}}
>
> I hope someone can help me out here.
>
> Thanks a lot,
> Udera
>
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