Monthly Archives: November 2018

OpenDKIM in Debian

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Lately I’ve been playing with postfix and ways to validate my mail. That’s how I reached DKIM records. Something like ssh keys (a public and private key) but for mail. Installation in Debian GNU/Linux is pretty simple via apt-get as usual, we need to install opendkim and opendkim-tools.

dpkg -l | grep dkim
ii  libmail-dkim-perl              0.40-1                           all          cryptographically identify the sender of email - perl library
ii  libopendkim9                   2.9.2-2+deb8u1                   amd64        Library for signing and verifying DomainKeys Identified Mail signatures
ii  opendkim                       2.9.2-2+deb8u1                   amd64        Milter implementation of DomainKeys Identified Mail
ii  opendkim-tools                 2.9.2-2+deb8u1                   amd64        Set of command line tools for OpenDKIM

We need to open a port for opendkim (8891 in my case), we need to edit /etc/default/opendkim in order to do this as below.

grep -v "^#" /etc/default/opendkim 
SOCKET="inet:8891@localhost" # listen on loopback on port 8891

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Spamassassin logs to a different file

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Lately I’ve been looking at my mail logs and noticed that on them it gets written spam, postfix and dovecot messages among other, which is a little uncomfortable. We can use grep to filter, but perhaps a better approach is to send spamassassin logs to a different file.

tail /var/log/mail.log
Oct 16 17:13:11 myserver postfix/smtpd[29869]: connect from unknown[185.234.219.254]
Oct 16 17:13:11 myserver postfix/smtpd[29869]: warning: unknown[185.234.219.254]: SASL LOGIN authentication failed: Invalid authentication mechanism
Oct 16 17:13:11 myserver postfix/smtpd[29869]: lost connection after AUTH from unknown[185.234.219.254]
Oct 16 17:13:11 myserver postfix/smtpd[29869]: disconnect from unknown[185.234.219.254]
Oct 16 17:15:53 myserver postfix/smtpd[29896]: warning: hostname 204.152.209.101.static.quadranet.com does not resolve to address 204.152.209.101
Oct 16 17:15:53 myserver postfix/smtpd[29896]: connect from unknown[204.152.209.101]
Oct 16 17:15:53 myserver postfix/smtpd[29896]: warning: unknown[204.152.209.101]: SASL LOGIN authentication failed: Invalid authentication mechanism
Oct 16 17:15:54 myserver postfix/smtpd[29896]: disconnect from unknown[204.152.209.101]
Oct 16 17:16:41 myserver postfix/smtpd[29896]: warning: hostname unassigned.quadranet.com does not resolve to address 192.161.170.229
Oct 16 17:16:41 myserver postfix/smtpd[29896]: connect from unknown[192.161.170.229]
Oct 16 17:16:42 myserver postfix/smtpd[29896]: Anonymous TLS connection established from unknown[192.161.170.229]: TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)
Oct 16 17:17:03 myserver postfix/smtpd[29896]: warning: eotzqh.kylieslowcase.fun.blackhole.securitysage.com: RBL lookup error: Host or domain name not found. Name service error for name=eotzqh.kylieslowcase.fun.blackhole.securitysage.com type=A: Host not found, try again
Oct 16 17:17:05 myserver postfix/smtpd[29896]: DA88C2607C5: client=unknown[192.161.170.229]
Oct 16 17:17:06 myserver postfix/cleanup[29903]: DA88C2607C5: message-id=
Oct 16 17:17:06 myserver postfix/qmgr[1238]: DA88C2607C5: from=, size=32258, nrcpt=1 (queue active)
Oct 16 17:17:06 myserver postfix/smtpd[29896]: disconnect from unknown[192.161.170.229]
Oct 16 17:17:08 myserver postfix/pickup[29368]: 3D6B4260878: uid=5001 from=
Oct 16 17:17:08 myserver postfix/pipe[29904]: DA88C2607C5: to=, relay=spamassassin, delay=26, delays=24/0.01/0/1.9, dsn=2.0.0, status=sent (delivered via spamassassin service)
Oct 16 17:17:08 myserver postfix/qmgr[1238]: DA88C2607C5: removed
Oct 16 17:17:08 myserver postfix/cleanup[29903]: 3D6B4260878: message-id=
Oct 16 17:17:08 myserver postfix/qmgr[1238]: 3D6B4260878: from=, size=32672, nrcpt=1 (queue active)
Oct 16 17:17:08 myserver postfix/pipe[29908]: 3D6B4260878: to=, relay=dovecot, delay=0.22, delays=0.07/0.01/0/0.14, dsn=2.0.0, status=sent (delivered via dovecot service)
Oct 16 17:17:08 myserver postfix/qmgr[1238]: 3D6B4260878: removed
Oct 16 17:17:51 myserver postfix/smtpd[29896]: connect from unknown[185.36.81.87]
Oct 16 17:17:51 myserver postfix/smtpd[29896]: warning: unknown[185.36.81.87]: SASL LOGIN authentication failed: Invalid authentication mechanism
Oct 16 17:17:51 myserver postfix/smtpd[29896]: lost connection after AUTH from unknown[185.36.81.87]
Oct 16 17:17:51 myserver postfix/smtpd[29896]: disconnect from unknown[185.36.81.87]
Oct 16 17:18:49 myserver postfix/smtpd[29896]: connect from unknown[187.55.179.130]
Oct 16 17:18:50 myserver postfix/smtpd[29896]: warning: unknown[187.55.179.130]: SASL LOGIN authentication failed: Invalid authentication mechanism
Oct 16 17:18:50 myserver postfix/smtpd[29896]: lost connection after AUTH from unknown[187.55.179.130]
Oct 16 17:18:50 myserver postfix/smtpd[29896]: disconnect from unknown[187.55.179.130]
Oct 16 17:19:50 myserver postfix/smtpd[29896]: warning: hostname 204.152.209.101.static.quadranet.com does not resolve to address 204.152.209.101
Oct 16 17:19:50 myserver postfix/smtpd[29896]: connect from unknown[204.152.209.101]
Oct 16 17:19:51 myserver postfix/smtpd[29896]: warning: unknown[204.152.209.101]: SASL LOGIN authentication failed: Invalid authentication mechanism
Oct 16 17:19:51 myserver postfix/smtpd[29896]: disconnect from unknown[204.152.209.101]
Oct 16 17:21:21 myserver postfix/anvil[29719]: statistics: max connection rate 1/60s for (smtp:177.143.199.94) at Oct 16 17:12:24

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