sendmail relay block (no forge email)

hello all,

i am using Cent OS 3.0, i have implemented sendmail server.
i m new in this field.
i found that when any body telnet on my server's port 25, they can
send mail from other id to any one
for example =>


220 example.com ESMTP Sendmail 8.12.10/8.12.10; Wed, 30 Oct 2007
00:4
5:19 +0530

helo gmail.com
250 example.com Hello ABTS-mp-
dynamic-254.24.168.122.airtelbroadband.in [1
22.168.24.254] (may be forged), pleased to meet you
mail from: bkarankar@gmail.com
250 2.1.0 bkarankar@gmail.com... Sender ok
rcpt to: bkarankar@gmail.com
250 2.1.5 bkarankar@gmail.com... Recipient ok
data
354 Enter mail, end with "." on a line by itself
subject: test
this is forge
..
250 2.0.0 l9UJFJvu009254 Message accepted for delivery
quit
221 2.0.0 example.com closing connection


Connection to host lost.


this mean my mail server accepting forge email, this is providing spam
facility for spammer.

Can any body help me to block it.

our client need to send and recd mail from outside domain.
how can i block this access, that can no body can miss use my mail
server.

Regarding configuration, i have just put dnl on line 127.0.0.1 MTA and
nothing..........
if possible then guide me step by step for what to do.

should i have to implement smtp auth, if yes, then also help me in
cofigure this.


Thanking you
Wating for your reply
Bhupesh Karankar
bkarankar@gmail.com
+919826233508

Re: sendmail relay block (no forge email)

These are both so old now, mant security updates since, i suggest you
remove the sendmail packages and get the 8.14.1 source from sendmail.org
and install from there.

On Tue, 30 Oct 2007, bkarankar wrote:

>
> hello all,
>
> i am using Cent OS 3.0, i have implemented sendmail server.
> i m new in this field.
> i found that when any body telnet on my server's port 25, they can
> send mail from other id to any one
> for example =>
>
>
> 220 example.com ESMTP Sendmail 8.12.10/8.12.10; Wed, 30 Oct 2007
> 00:4
> 5:19 +0530
>
> helo gmail.com
> 250 example.com Hello ABTS-mp-
> dynamic-254.24.168.122.airtelbroadband.in [1
> 22.168.24.254] (may be forged), pleased to meet you
> mail from: bkarankar@gmail.com
> 250 2.1.0 bkarankar@gmail.com... Sender ok
> rcpt to: bkarankar@gmail.com
> 250 2.1.5 bkarankar@gmail.com... Recipient ok
> data
> 354 Enter mail, end with "." on a line by itself
> subject: test
> this is forge
> .
> 250 2.0.0 l9UJFJvu009254 Message accepted for delivery
> quit
> 221 2.0.0 example.com closing connection
>
>
> Connection to host lost.
>
>
> this mean my mail server accepting forge email, this is providing spam
> facility for spammer.
>
> Can any body help me to block it.
>
> our client need to send and recd mail from outside domain.
> how can i block this access, that can no body can miss use my mail
> server.
>
> Regarding configuration, i have just put dnl on line 127.0.0.1 MTA and
> nothing..........
> if possible then guide me step by step for what to do.
>
> should i have to implement smtp auth, if yes, then also help me in
> cofigure this.
>
>
> Thanking you
> Wating for your reply
> Bhupesh Karankar
> bkarankar@gmail.com
> +919826233508
>
>

--
Cheers
Res

Re: sendmail relay block (no forge email)

On Tue, 30 Oct 2007 19:20:26 -0000, bkarankar wrote:
> hello all,
> i am using Cent OS 3.0, i have implemented sendmail server.
> i m new in this field.
> i found that when any body telnet on my server's port 25, they can
> send mail from other id to any one for example =>
>
> 220 example.com ESMTP Sendmail 8.12.10/8.12.10; Wed, 30 Oct 2007
> 00:45:19 +0530
>
> helo gmail.com
> 250 example.com Hello ABTS-mp-
> dynamic-254.24.168.122.airtelbroadband.in [1
> 22.168.24.254] (may be forged), pleased to meet you
> mail from: bkarankar@gmail.com
> 250 2.1.0 bkarankar@gmail.com... Sender ok
> rcpt to: bkarankar@gmail.com
> 250 2.1.5 bkarankar@gmail.com... Recipient ok
> data
> 354 Enter mail, end with "." on a line by itself
> subject: test
> this is forge
> .
> 250 2.0.0 l9UJFJvu009254 Message accepted for delivery
> quit
> 221 2.0.0 example.com closing connection

Are you testing by telnetting from an *external* address? If yes, then
your Sendmail installation is an open relay, and it should be fixed.

> this mean my mail server accepting forge email, this is providing spam
> facility for spammer.

If you haven't taken explicit steps to make Sendmail an open relay, then
this should not happen :/