Re: Spammer succeeded in relaying through my server

[Samer Afach]

Thank you. You and Pat actually may be onto something. I grepped the whole logs for "connect from", and all the "connect from" and "disconnect from" statements seem to be coming from 172.30.0.1, which, if I understand correctly, is the NAT bridge address of docker, i.e., the subnet router address. What is the correct solution in this case, based on my configuration? Please advise. I understand I have to make "mynetworks" just localhost, but specific recommendation based on my configuration would be highly appreciated. Best regards, Sam On 21/12/2022 11:51 AM, mailm...@ionos.gr wrote: The most common issue when using a proxy/load balancer like haproxy, is that the remote/foreign connections are being forwarded with the IP address of the haproxy machine. Thus, they all appear as "local", which makes postfix think they are "mynetworks" and as a result, postfix becomes a open relay. So check your logs, to make sure remote/foreign connections don't appear as 172.30.0.0/16 in postfix. If they do, then that is the problem. On Wed, 21 Dec 2022 11:35:13 +0400 Samer Afach <samer.af...@msn.com> wrote: Dear Pat: Thank you for throwing this idea, because I really thought it wasn't possible to retrieve docker logs without setup, but I dug and found the logs. I have them all. Unfortunately, I can't share them all because they're like GBs in size. Just the grep on that email address is like 750 MB in size. I cut a snippet of the relevant part (where I see the spam address), and put it in pastebin. I hope that's allowed in the rules of the list. https://pastebin.com/PEir7mDc (all from postfix, nothing from dovecot, btw). I minimally redacted the logs: - The domains example.com and example.org belong to me, seems like both were involved in this attack. - My public IP address was replaced with 123.456.789.123 Please note that 172.30.0.0/16 is the docker-compose subnet for all dockerized email applications. It was created automatically by docker-compose. If you need any additional information or additional logs, please let me know. Best regards, Sam On 21/12/2022 10:31 AM, Patrick Proniewski wrote: Hello, Do you have the logs (postfix and maybe dovecot) showing the spammer interaction with the server? pat On 21 Dec 2022, at 05:45, Samer Afach <samer.af...@msn.com> wrote: Thank you, Phil. Here we go. Here's postconf -n: I hope this helps in better identifying how the spammer was able to use my server to send a spam email. ``` alias_database = hash:/etc/aliases alias_maps = hash:/etc/aliases append_dot_mydomain = no biff = no broken_sasl_auth_clients = yes debug_peer_level = 6 debug_peer_list = 0.0.0.0/0 disable_vrfy_command = yes inet_interfaces = all inet_protocols = ipv4 mailbox_size_limit = 0 maillog_file = /dev/stdout message_size_limit = 0 milter_default_action = accept milter_protocol = 2 mydestination = hostname.hosting-service.com, localhost.hosting-service.com, localhost myhostname = localhost mynetworks_style = subnet myorigin = localhost non_smtpd_milters = inet:docker-email-opendkim:12301 proxy_read_maps = $local_recipient_maps $mydestination $virtual_alias_maps $virtual_alias_domains $virtual_mailbox_maps $virtual_mailbox_domains $relay_recipient_maps $relay_domains $canonical_maps $sender_canonical_maps $recipient_canonical_maps $relocated_maps $transport_maps $mynetworks $smtpd_sender_login_maps readme_directory = no recipient_delimiter = + relay_domains = relayhost = smtp_tls_cert_file = /shared-keys/example.com/fullchain.pem smtp_tls_key_file = /shared-keys/example.com/privkey.pem smtp_tls_loglevel = 1 smtp_tls_mandatory_protocols = !SSLv2,!SSLv3,!TLSv1,!TLSv1.1 smtp_tls_protocols = !SSLv2,!SSLv3,!TLSv1,!TLSv1.1 smtp_tls_session_cache_database = btree:${data_directory}/smtp_scache smtpd_banner = $myhostname ESMTP $mail_name (Debian/GNU) smtpd_client_restrictions = permit_mynetworks smtpd_helo_restrictions = reject_invalid_helo_hostname, smtpd_milters = inet:docker-email-opendkim:12301 smtpd_recipient_restrictions = check_sender_access hash:/etc/postfix/sender_access, permit_sasl_authenticated, permit_mynetworks, reject_unauth_destination, reject_invalid_hostname, reject_unknown_recipient_domain, reject_unauth_destination, reject_rbl_client sbl.spamhaus.org, reject_rbl_client b.barracudacentral.org, reject_rbl_client zen.spamhaus.org, reject_rbl_client truncate.gbudb.net, reject_rbl_client bl.spamcop.net, reject_rbl_client cbl.abuseat.org, smtpd_relay_restrictions = permit_sasl_authenticated permit_mynetworks reject_unauth_destination smtpd_sasl_auth_enable = yes smtpd_sasl_authenticated_header = yes smtpd_sasl_path = /shared-socks/auth_dovecot smtpd_sasl_type = dovecot smtpd_sender_login_maps = proxy:mysql:/etc/postfix/mysql_sender_login_maps.cf smtpd_tls_auth_only = yes smtpd_tls_cert_file = /shared-keys/example.com/fullchain.pem smtpd_tls_ciphers = high smtpd_tls_key_file = /shared-keys/example.com/privkey.pem smtpd_tls_mandatory_protocols = !SSLv2,!SSLv3,!TLSv1,!TLSv1.1 smtpd_tls_protocols = !SSLv2,!SSLv3,!TLSv1,!TLSv1.1 smtpd_tls_security_level = may smtpd_tls_session_cache_database = btree:${data_directory}/smtpd_scache smtpd_use_tls = yes virtual_alias_maps = proxy:mysql:/etc/postfix/mysql_virtual_alias_maps.cf virtual_gid_maps = static:5000 virtual_mailbox_base = /var/vmail/ virtual_mailbox_domains = proxy:mysql:/etc/postfix/mysql_virtual_domains_maps.cf virtual_mailbox_limit = 0 virtual_mailbox_maps = proxy:mysql:/etc/postfix/mysql_virtual_mailbox_maps.cf virtual_minimum_uid = 104 virtual_transport = lmtp:inet:docker-email-dovecot:10024 virtual_uid_maps = static:5000 ``` Best regards, Sam On 21/12/2022 8:35 AM, Phil Stracchino wrote: On 12/20/22 21:39, Samer Afach wrote: I could share postconf too, but it's huge and I don't want to make this a huge burden unless necessary. 'postconf -n' is much more concise. Try it.