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2d
answered Unable to resolve IP Blacklisting with Spamhaus
May
19
revised Block brute force attacks on exim2
Clarify
May
19
answered Block brute force attacks on exim2
May
10
revised Using public ntp servers for backup to local stratum 1 server
Add details re e-mail
May
10
answered Using public ntp servers for backup to local stratum 1 server
May
3
revised Spam delivered by mx.google.com despite SPF fail
added 1 character in body
May
3
comment ntpd: servers stuck on .INIT
The rule for ntp should allow outgoing traffic. Responses should be covered by a ctstate RELATED,ESTABLISHED input rule.
May
3
answered Spam delivered by mx.google.com despite SPF fail
May
1
comment fail2ban keeps trying to ban again
@Michael Try setting the ban file in /tmp. If fail2ban is not running as root it can't create the file in /etc.
May
1
comment fail2ban keeps trying to ban again
@Michael Updated answer with a tested script. Remove pattern should be '^$2\$' rather than '^$2$'. It is testable from the keyboard,
May
1
revised fail2ban keeps trying to ban again
Replace with tested script
May
1
revised fail2ban keeps trying to ban again
added 666 characters in body
May
1
comment fail2ban keeps trying to ban again
@Michael I've updated my answer with a sample script and related actions. I did not test the script, you should verify it manually before putting it into production. Under high volumes of ban/unban traffic it may not update the blacklist file correctly.
May
1
comment fail2ban keeps trying to ban again
@Michael include the call to ban the IP address inside the if statement.
Apr
30
answered fail2ban keeps trying to ban again
Apr
28
comment NTP running, server time is wrong on VM
I have had issues running ntp on virtual machines. Unless the clock is virtual, ntpd may try to modify the system clock. Normally an issue like this is a result of the system expecting the hardware clock to set to a different time than it is actually set to. The container usually has a timesync mechanism, which appears to be disabled.
Apr
27
comment Why is it important that servers have the exact same time?
@rmalayter Glad to hear Microsoft fixed their implementation. I generally work in mixed (often dated) environments where the old implementation is still in place. I still run into servers which should be in the the AD domain that are minutes off the current time.
Apr
26
comment Why is it important that servers have the exact same time?
Servers running an NTP daemon are typically synchonized to within 0.01 seconds (a few milliseconds). The native Windows NTP synchronization only checks a few times a day, and is not as accurate. There are NTP clients available for Windows, that provide good synchronization.
Apr
22
comment SPF records clarification of using A mechanism
@ValeraTumash Mail should be sent from an mx using a sub-domain such as smtp.example.com. Raw domains such as example.com tend to be used by spambots rather than legitimate mailers.
Apr
22
comment SPF records clarification of using A mechanism
@MadHatter I've corrected the non-sending domain. Missed cleanup up the paste. Thanks