i have never opened telnet ok , my xinetd service is off so there is no telnet service , i m doing telnet to outside to 25 port on my mail server and there is proper smtp authentication enabled on server , the problem is anyuser (non-existing) with my domain can send mail to my real domain users. below is example........
##EXAMPLE 1>
telnet 192.168.1.4 25 220 UNAUTHORIZED ESMTP ACCESS IS PROHIBITED
220 UNAUTHORIZED ESMTP ACCESS IS PROHIBITED mail.domain.com ehlo domain.com 250-mail.domain.com Hello [192.168.1.5], pleased to meet you 250-ENHANCEDSTATUSCODES 250-PIPELINING 250-8BITMIME 250-SIZE 250-DSN 250-AUTH DIGEST-MD5 CRAM-MD5 PLAIN LOGIN 250-STARTTLS 250-DELIVERBY 250 HELP MAIL FROM:axy@domain.com 250 2.1.0 axy@domain.com... Sender ok RCPT TO:abhi@domain.com 250 2.1.5 abhi@domain.com... Recipient ok DATA 354 Enter mail, end with "." on a line by itself this is bad . 250 2.0.0 k8L4I0FL004621 Message accepted for delivery quit 221 2.0.0 mail.domain.com closing connection #################################################### EXAMPLE-2
telnet 192.168.1.4 25
220 UNAUTHORIZED ESMTP ACCESS IS PROHIBITED mail.domain.com ehlo domain.com 250-mail.domain.com Hello [192.168.1.5], pleased to meet you 250-ENHANCEDSTATUSCODES 250-PIPELINING 250-8BITMIME 250-SIZE 250-DSN 250-AUTH DIGEST-MD5 CRAM-MD5 PLAIN LOGIN 250-STARTTLS 250-DELIVERBY 250 HELP MAIL FROM:alex@mai.com 250 2.1.0 alex@mai.com... Sender ok RCPT TO:abhi@domain.com 250 2.1.5 abhi@domain.com... Recipient ok DATA 354 Enter mail, end with "." on a line by itself hjsdhkjhdfkjhsdkf sfdkdkfjdkg . 250 2.0.0 k8L4LUMY004822 Message accepted for delivery quit 221 2.0.0 mail.domain.com closing connection
Connection to host lost.
In above example u can see in the 1st example the sender(xyz) is not real user of my domain , still he is able to sendmail to my real users (abhi).
In second scenario sender is able to send mail by forging domain name by any domain to my domain users.
i have replaced my real domain name with domain.com and i have to do same thing from out side network , in my /etc/mail/access file only 127.0.0.1 is allowed .
when i am trying to send mail to another domain then relaying is denied means my mail server is not open relay.
plz help me.
Abhishek Kr. Singh System Administrator DSC. LTD. Mob.No. +91-9871563248
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