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Subject: How to use DNSBL

12/08/2006 21:47 FromOldForum:
There is no description for DNSBL, how use this feature. I try spamcop etc and nothing happens!
12/08/2006 21:53 Max:
You may just direct hostname of external DNSBL server.
In this case SMTP will ask about remote IP from this server, before receive the message. If DNSBL server reply that it is spamer connection will be droped.

13/08/2006 06:01 Mi:
Im the first user of new forum? :)
OK, I try another DNSBL servers.
It be wonderful if SMTP will ask more than one DNSBL server, like spamassassin or spampal.

Good work Max.
25/08/2006 23:49 Max:
Ok. New version 3.05.58 can ask more then one server.
Now in this field you can direct more then one hosts through space.
28/08/2006 01:23 Mi:
But IMHO bug still exist:
Ver. 3.05.58a Windows (my system 98se)
Today, using packet capture, I found that Shttps asks DNS with not reversed IP. IP must be reversed like in PTR question.
"For example, if you want to check if is on the blacklist, you might type this at the command-line:
If you get back an IP address (typically, then the IP you asked about is listed. If you get back a non-existant message, then the IP you asked about is not listed. "
( ..

28/08/2006 03:15 Max:
Oh, yes, probably you right.
This fixed in version 3.05.59
14/09/2006 00:03 Mi:
Yes, now DNSBL works very good.

But if something is working good, we can always make it better:

Problem 1.

DNSBL is very good in veryfing SMTP servers, but not good when it`s blocking email clients of our users.

IPs in SMTP option: "IPs that can access this server" and "Temporary added IPs to allowed list after POP3 authorization" should be excluded from DNSBL checking or must be an option to exclude them.

14/09/2006 00:09 Mi:
Let me explain:
In "IPs that can access this server" setting are only my local LAN addresses or very trusted internet IPs, allowed to sending mail from local user to any user, it`s no sense for querrying about them the DNSBL system.

Sometimes local user is roaming somewhere in the internet, for example using GPRS, hotspot point etc.
We can authorize this user with "POP before SMTP" feature, if TLS is used - this is very reliable and secure method. If I use DNSBL server which is blocking all dynamic IP ranges, roaming user is unable to send mail.
14/09/2006 00:47 Mi:
Problem 2.

You can easy add another IP-based antispam feature: reverse DNS lookup and rejecting mail from IPs without valid PTR record.
It took one or two DNS questions: First for PTR hostname and second for sure that hostame have at least one A record pointing to the same IP.
14/09/2006 02:06 Max:
No, rejecting mail from IPs without valid PTR is very bad idea. Why? Does it is spamers IPs? I`m self doesn`t have PTR address for my IP, because my Internet provider don`t update PTR manualy, and haven`t interface for users for it.

What question about PTR? You may create PTR records and special zone for these records
You may create more then one A records pointed to the same IP it is correct.
About alowed IPs, -- in next version I try to fix it.
14/09/2006 08:24 Mi:
OK, yes, probably you right about PTR. Multiple A for one hostname is correct (used for load ballancing?). Multiple PTR for one IP is correct too (i don`t know what for). Some of ISP are not providing PTR for their clients (bad ISP). Some IPs have totally false PTR like localhost or ! I think about that irresponsible or hijacked networks, but forget about it. However every IP in the internet should have PTR record due to RFC rules.
14/09/2006 08:52 Mi:
Shttps antispam is enough very strong. You can think about SPF implementation in the indefinite future. However SPF is rather hard to implement: complicated syntax, multiple mechanisms, multiple DNS querries and fuzzy logic like softfail and neutral qualifiers. But if domain administrator create good SPF record we know whitch IPs are allowed to send e-mail from his domain. It`s work for more than few days but I`m think SPF is quite good method.
03/10/2006 07:46 babe1:
Rules rules rules rules!! ok.. now where we..
i have a problem with linux because when i try to open a file whatever it shows me that---

and the root of the website is on /var/www
when i try to open index.htm says
Error. Bad request.
what is that, and why?
thanks very much
btw the server is runing on port 81
i can directory listing but i cant open files
04/10/2006 02:21 Max:
At first, put server and his config into web directory is very bad idea.

At second, probably it is another subject, in this forum easy to create new subject for discussion.

And at last the ansver, -- under Linux the server return only files that have "readable for all" attribute.
use the comand `chmod` to change access mode:
chmod a+r index.htm
-- to add `readable for all` for index.htm
chmod ago+r *
to add readable for all,group,owner for each file in current directory
chmod 0555 index.htm
to set readable and writable mode for all,group,owner

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