Re: Fail2ban & logrotate [was: Update on spam, postfix, fail2ban, centos 6]

Bob Hoffman <bob@xxxxxxxxxxxxxx> · Sun, 17 Jun 2012 23:41:51 -0400

Here is what I had to do to make fail2ban work with centos 6, fail2ban 
from epel
This is a long letter and no html to make it read better.
It deals with failed jails during start, loss of ban/unban after systems 
logrotates files, errors in jails,
sasl errors, logging file correctly to work with fail2ban and logwatch, 
fail2ban logrotate.

I hope this helps others, it was a real bear and the first program/rpm I 
used that really does not work very well as set up.
(a update was pushed a few weeks back, not sure how this affects 
anything below...mine still works as is.)
Forgive me if I left something out.

first I added these programs to the EPEL repo ( I do not allow any 
except those I use, so I use the following to limit the repo.)

includepkgs= fail2ban shorewall shorewall-core python-inotify gamin-python

Fail2ban has recently been updated on the epel repo and shorewall-core 
is now needed too, this is new.
How the new updates affects any of the below is beyond me, but I doubt 
it changed anything.

1st issue
------------------
/etc/fail2ban/jail.conf
change line 39 to
backend = gamin

Without this fail2ban will ignore log rotations by logrotate and stay on 
the old file in your jails.
This was needed or it failed. No errors, nothing.
Force log rotate did not make this happen, only the program running each 
morning did it.
I changed mine to a daily rotate of /var/log/secure,vsftpd.log, etc... 
to test this.
Without gamin it failed every time.

(also you need to add this)
line 16 (add your ip (or ip block?) after the 127 ip) Use a space 
between them all.
ignoreip = 127.0.0.1 yourip

2nd issue
-------------------
with more than one jail you can (and will) get chances of errors when 
starting fail2ban. Some people seem to attribute it centos 6
having an older version of netfilter. The program goes to fast for 
iptables and chokes setting up the chains.
Sometimes they all go on, most times I would lose one to two chains 
during each restart of fail2ban.

You have to have debug with at least 'info' to see these errors. When 
stopping you will get a ton of these errors too, but they seem
to have no effect on anything.

To stop these errors and allow all jails to start properly you have to 
add a sleep line deep in the code.
I have not tested since the update to see if this was overwritten but 
will do that this week.

/usr/bin/fail2ban-client

Find the following code and add the time.sleep(0.1) in there as I have.
You need to press the tab 3 times to indent it, python pays attention to 
white space, it will choke if you do not do this.

add sleep command into the following, (tab three times)
starts at line 142
def __processCmd(self, cmd, showRet = True):
     beautifier = Beautifier()
     for c in cmd:
         time.sleep(0.1)
         beautifier.setInputCmd(c)
         try:

This lets netfilter catch up with the fail2ban client and allows all 
jails to get started properly.
If you only use one jail this would not be needed, but each one after 
that offers a chance of not being turned on.

3rd issue
-------------------
The whole log thing is borked.
if you try to use fail2ban.log, fail2ban itself will choke on it.
If you try to use the repo's set up of using /var/log/messages than 
logwatch will get borked on it.
However, if you set it all to /var/log/fail2ban as the log file, it will 
work.

No matter which way you want it, logwatch, fail2ban, and logrotate all 
point to different files for logging and it is a real mess.

Here is what I did to make it log and allow logrotate to work with it.

/etc/fail2ban/fail2ban.conf
line 25
logtarget = /var/log/fail2ban

/etc/logrotate.d/fail2ban
Below I changed the logtarget and stopped the 'restart' the repo wanted. 
Thus it will keep running day after day.

/var/log/fail2ban {
     missingok
     notifempty
     rotate 7
     create 0600 root root
     postrotate
         /usr/bin/fail2ban-client set logtarget /var/log/fail2ban 2> 
/dev/null || true
     endscript
}

finally for logwatch
/usr/share/logwatch/default.conf/logfiles/fail2ban.conf
LogFile = fail2ban
Archive = fail2ban-*

------------------------------------------------------------------------------------------------------------------
jails I set up...this is gonna be quick with little info, still writing 
notes for the book on this one
I lowered the times in them for this letter, but mine are much higher.
I separated the ports for each for testing and safety. You could make 
all the ports blocked if you wanted too.

The first ssh in the repo is enabled by default I think. Make sure if 
you use these you check all others to make sure they
are not enabled.

[ssh-iptables]

enabled  = true
filter   = sshd
action   = iptables[name=SSH, port="22444", protocol=tcp]
logpath  = /var/log/secure
maxretry =  2
bantime  = 3600

[apache-tcp]
enabled  = true
filter     = apache-auth
bantime  = 10000
action   = iptables[name=ApacheAuth, port="80", protocol=tcp]
logpath  = /var/log/httpd/error_log
maxretry = 3

[apache-ssl]
enabled  = true
filter     = apache-auth-ssl
bantime  = 10000
action   = iptables[name=ApacheAuthSsl, port="443", protocol=tcp]
logpath  = /var/log/httpd/ssl_error_log
maxretry = 3

[vsftpd-iptables]
enabled  = true
filter   = vsftpd
action   = iptables[name=VSFTPD, port="5000", protocol=tcp]
logpath  = /var/log/vsftpd.log
maxretry = 3
bantime  = 3600

[Dovecot]
enabled  = true
filter   = dovecot
bantime  = 3600
maxretry = 2
action   = iptables-multiport[name=DOVECOT, port="25,465,993,995", 
protocol=tcp]
logpath  = /var/log/maillog

[Postfix]
enabled  = true
filter   = postfix
maxretry = 2
bantime  = 3600
findtime  = 3600
action   = iptables-multiport[name=POSTFIX, port="25,465,993,995", 
protocol=tcp]
logpath  = /var/log/maillog
[Postfix-sasl]
enabled  = true
filter   = sasl
maxretry = 4
bantime  = 3600
findtime  = 3600
action   = iptables-multiport[name=POSTFIX-SASL, port="25,465,993,995", 
protocol=tcp]
logpath  = /var/log/maillog

There was not one for dovecot, so I had to make one..
I do not think it is needed though, but I added it anyway (both go to 
maillog, but I figured I could do things with the jail later)

Here are some files I had to add to make the above jails work.
#####################################
make a new file called dovecot.conf as below
/etc/fail2ban/filter.d/dovecot.conf

[Definition]
# Option:  failregex
# Notes.:  regex to match the password failures messages in the logfile. The
#          host must be matched by a group named "host". The tag 
"<HOST>" can
#          be used for standard IP/hostname matching.
# Values:  TEXT
#

failregex = (?: pop3-login|imap-login): (?:Authentication 
failure|Aborted login \(auth failed|Aborted login \(tried to use 
disabled|Disconnected \(auth failed).*rip=(?P<host>\S*),.*

# Option:  ignoreregex
# Notes.:  regex to ignore. If this regex matches, the line is ignored.
# Values:  TEXT
#
ignoreregex =

####################################

for my apache auth I added this one from someone online too

#######################
make a new file
/etc/fail2ban/filter.d/apache-auth-ssl.conf
# Fail2Ban configuration file
#
# Author: Cyril Jaquier
#
# $Revision: 728 $
#

[Definition]

# Option:  failregex
# Notes.:  regex to match the password failure messages in the logfile. The
#          host must be matched by a group named "host". The tag 
"<HOST>" can
#          be used for standard IP/hostname matching and is only an 
alias for
#          (?:::f{4,6}:)?(?P<host>[\w\-.^_]+)
# Values:  TEXT
#
failregex = [[]client <HOST>[]] user .* authentication failure
             [[]client <HOST>[]] user .* not found
             [[]client <HOST>[]] user .* password mismatch

# Option:  ignoreregex
# Notes.:  regex to ignore. If this regex matches, the line is ignored.
# Values:  TEXT
#
ignoreregex =
###############################

for postfix I had to add somethings to block spam. I had made some 
errors to default to 550 to lower spam attempts too.

/etc/fail2ban/filter.d/postfix.conf
failregex = reject: RCPT from (.*)\[<HOST>\]: 554
             reject: RCPT from (.*)\[<HOST>\]: 550
             reject: RCPT from (.*)\[<HOST>\]: 504

(still need to add a 501 in there too for invalid names)

#############################################
for the sasl/postfix to work properly some changes were made, this is my 
file. The one that came with the repo will not work.
At least it did not work for me.

/etc/fail2ban/filter.d/sasl.conf

this is my file

# Fail2Ban configuration file
#
# Author: Yaroslav Halchenko
#
# $Revision: 728 $
#

[Definition]

# Option: failregex
# Notes.: regex to match the password failures messages in the logfile. The
#          host must be matched by a group named "host". The tag 
"<HOST>" can
#          be used for standard IP/hostname matching and is only an 
alias for
#          (?:::f{4,6}:)?(?P<host>[\w\-.^_]+)
# Values: TEXT
#
failregex = (?i): warning: [-._\w]+\[<HOST>\]: SASL 
(?:LOGIN|PLAIN|(?:CRAM|DIGEST)-MD5) authentication failed(: 
[A-Za-z0-9+/]*={0,2})?$
             (?i): warning: [-._\w]+\[<HOST>\]: SASL 
(?:LOGIN|PLAIN|(?:CRAM|DIGEST)-MD5) authentication failed: Invalid 
authentication mechanism
             (?i): warning: [-._\w]+\[<HOST>\]: SASL 
(?:LOGIN|PLAIN|(?:CRAM|DIGEST)-MD5) authentication failed.*
# Option:  ignoreregex
# Notes.:  regex to ignore. If this regex matches, the line is ignored.
# Values:  TEXT
#
ignoreregex =

###################################################

here is my iptables with some things taken out for security...lol

##############################################
[root@ ~]# iptables -L -n

Chain INPUT (policy ACCEPT)
target     prot opt source               destination
fail2ban-VSFTPD  tcp  --  0.0.0.0/0            0.0.0.0/0           tcp 
dpt:xx
fail2ban-DOVECOT  tcp  --  0.0.0.0/0            0.0.0.0/0           
multiport dports 25,465,993,995
fail2ban-POSTFIX  tcp  --  0.0.0.0/0            0.0.0.0/0           
multiport dports 25,465,993,995
fail2ban-ApacheAuthSsl  tcp  --  0.0.0.0/0            
0.0.0.0/0           tcp dpt:443
fail2ban-ApacheAuth  tcp  --  0.0.0.0/0            0.0.0.0/0           
tcp dpt:80
fail2ban-SSH  tcp  --  0.0.0.0/0            0.0.0.0/0           tcp 
dpt:22444
fail2ban-POSTFIX-SASL  tcp  --  0.0.0.0/0            0.0.0.0/0           
multiport dports 25,465,993,995
ACCEPT     all  --  0.0.0.0/0            0.0.0.0/0           state 
RELATED,ESTABLISHED
ACCEPT     icmp --  0.0.0.0/0            0.0.0.0/0
ACCEPT     all  --  0.0.0.0/0            0.0.0.0/0
ACCEPT     tcp  --  0.0.0.0/0            0.0.0.0/0           state NEW 
tcp dpt:25
ACCEPT     tcp  --  0.0.0.0/0            0.0.0.0/0           state NEW 
tcp dpt:80
ACCEPT     tcp  --  0.0.0.0/0            0.0.0.0/0           state NEW 
tcp dpt:443
ACCEPT     tcp  --  0.0.0.0/0            0.0.0.0/0           state NEW 
tcp dpt:465
ACCEPT     tcp  --  0.0.0.0/0            0.0.0.0/0           state NEW 
tcp dpt:993
ACCEPT     tcp  --  0.0.0.0/0            0.0.0.0/0           state NEW 
tcp dpt:995
ACCEPT     tcp  --  0.0.0.0/0            0.0.0.0/0           state NEW 
tcp dpt:xx
ACCEPT     tcp  --  0.0.0.0/0            0.0.0.0/0           state 
RELATED,ESTABLISHED tcp dpt:xx
ACCEPT     tcp  --  0.0.0.0/0            0.0.0.0/0           state 
NEW,ESTABLISHED tcp dpt:xx
ACCEPT     tcp  --  0.0.0.0/0            0.0.0.0/0           tcp dpts:xx:xx
REJECT     all  --  0.0.0.0/0            0.0.0.0/0           reject-with 
icmp-host-prohibited

Chain FORWARD (policy ACCEPT)
target     prot opt source               destination
REJECT     all  --  0.0.0.0/0            0.0.0.0/0           reject-with 
icmp-host-prohibited

Chain OUTPUT (policy ACCEPT)
target     prot opt source               destination

Chain fail2ban-ApacheAuth (1 references)
target     prot opt source               destination
RETURN     all  --  0.0.0.0/0            0.0.0.0/0

Chain fail2ban-ApacheAuthSsl (1 references)
target     prot opt source               destination
RETURN     all  --  0.0.0.0/0            0.0.0.0/0

Chain fail2ban-DOVECOT (1 references)
target     prot opt source               destination
RETURN     all  --  0.0.0.0/0            0.0.0.0/0

Chain fail2ban-POSTFIX (1 references)
target     prot opt source               destination
RETURN     all  --  0.0.0.0/0            0.0.0.0/0

Chain fail2ban-POSTFIX-SASL (1 references)
target     prot opt source               destination
RETURN     all  --  0.0.0.0/0            0.0.0.0/0

Chain fail2ban-SSH (1 references)
target     prot opt source               destination
RETURN     all  --  0.0.0.0/0            0.0.0.0/0

Chain fail2ban-VSFTPD (1 references)
target     prot opt source               destination
RETURN     all  --  0.0.0.0/0            0.0.0.0/0

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