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I am getting some person(s) trying to brute force my ssh, from multiple ip addresses (small sample) :

May 22 19:50:02 rpi sshd[1272]: pam_unix(sshd:auth): authentication failure; logname= uid=0 euid=0 tty=ssh ruser= rhost=58.218.205.84  user=root

May 22 19:50:04 rpi sshd[1272]: Failed password for root from 58.218.205.84 port 50690 ssh2

May 22 19:50:06 rpi sshd[1272]: Failed password for root from 58.218.205.84 port 50690 ssh2

May 22 19:50:08 rpi sshd[1272]: Failed password for root from 58.218.205.84 port 50690 ssh2

May 22 19:50:09 rpi sshd[1272]: Received disconnect from 58.218.205.84: 11:  [preauth]

May 22 19:50:09 rpi sshd[1272]: PAM 2 more authentication failures; logname= uid=0 euid=0 tty=ssh ruser= rhost=58.218.205.84  user=root

May 22 19:50:10 rpi sshd[1276]: pam_unix(sshd:auth): authentication failure; logname= uid=0 euid=0 tty=ssh ruser= rhost=58.218.205.84  user=root

May 22 19:50:13 rpi sshd[1276]: Failed password for root from 58.218.205.84 port 58560 ssh2

May 22 19:50:15 rpi sshd[1276]: Failed password for root from 58.218.205.84 port 58560 ssh2

May 22 19:50:17 rpi sshd[1276]: Failed password for root from 58.218.205.84 port 58560 ssh2

May 22 19:50:18 rpi sshd[1276]: Received disconnect from 58.218.205.84: 11:  [preauth]

May 22 19:50:18 rpi sshd[1276]: PAM 2 more authentication failures; logname= uid=0 euid=0 tty=ssh ruser= rhost=58.218.205.84  user=root

May 22 19:50:24 rpi sshd[1280]: pam_unix(sshd:auth): authentication failure; logname= uid=0 euid=0 tty=ssh ruser= rhost=58.218.205.84  user=root

May 22 19:50:27 rpi sshd[1280]: Failed password for root from 58.218.205.84 port 34793 ssh2

May 22 19:50:29 rpi sshd[1280]: Failed password for root from 58.218.205.84 port 34793 ssh2

May 22 19:50:31 rpi sshd[1280]: Failed password for root from 58.218.205.84 port 34793 ssh2

May 22 19:50:31 rpi sshd[1280]: Received disconnect from 58.218.205.84: 11:  [preauth]

May 22 19:50:31 rpi sshd[1280]: PAM 2 more authentication failures; logname= uid=0 euid=0 tty=ssh ruser= rhost=58.218.205.84  user=root

So I installed fail2ban, however its not working. The config for it is :

# Fail2Ban configuration file.

#

# This file was composed for Debian systems from the original one

#  provided now under /usr/share/doc/fail2ban/examples/jail.conf

#  for additional examples.

#

# To avoid merges during upgrades DO NOT MODIFY THIS FILE

# and rather provide your changes in /etc/fail2ban/jail.local

#

# Author: Yaroslav O. Halchenko <debian@onerussian.com>

#

# $Revision$

#



# The DEFAULT allows a global definition of the options. They can be overridden

# in each jail afterwards.



[DEFAULT]



# "ignoreip" can be an IP address, a CIDR mask or a DNS host

ignoreip = 127.0.0.1/8 192.168.1.0/24

bantime  = 600

maxretry = 3



# "backend" specifies the backend used to get files modification. Available

# options are "gamin", "polling" and "auto".

# yoh: For some reason Debian shipped python-gamin didn't work as expected

#      This issue left ToDo, so polling is default backend for now

backend = auto



#

# Destination email address used solely for the interpolations in

# jail.{conf,local} configuration files.

destemail = root@localhost



#

# ACTIONS

#



# Default banning action (e.g. iptables, iptables-new,

# iptables-multiport, shorewall, etc) It is used to define

# action_* variables. Can be overridden globally or per

# section within jail.local file

banaction = iptables-multiport



# email action. Since 0.8.1 upstream fail2ban uses sendmail

# MTA for the mailing. Change mta configuration parameter to mail

# if you want to revert to conventional 'mail'.

mta = sendmail



# Default protocol

protocol = tcp



# Specify chain where jumps would need to be added in iptables-* actions

chain = INPUT



#

# Action shortcuts. To be used to define action parameter



# The simplest action to take: ban only

action_ = %(banaction)s[name=%(__name__)s, port="%(port)s", protocol="%(protocol)s", chain="%(chain)s"]



# ban & send an e-mail with whois report to the destemail.

action_mw = %(banaction)s[name=%(__name__)s, port="%(port)s", protocol="%(protocol)s", chain="%(chain)s"]

              %(mta)s-whois[name=%(__name__)s, dest="%(destemail)s", protocol="%(protocol)s", chain="%(chain)s"]



# ban & send an e-mail with whois report and relevant log lines

# to the destemail.

action_mwl = %(banaction)s[name=%(__name__)s, port="%(port)s", protocol="%(protocol)s", chain="%(chain)s"]

               %(mta)s-whois-lines[name=%(__name__)s, dest="%(destemail)s", logpath=%(logpath)s, chain="%(chain)s"]



# Choose default action.  To change, just override value of 'action' with the

# interpolation to the chosen action shortcut (e.g.  action_mw, action_mwl, etc) in jail.local

# globally (section [DEFAULT]) or per specific section

action = %(action_)s



#

# JAILS

#



# Next jails corresponds to the standard configuration in Fail2ban 0.6 which

# was shipped in Debian. Enable any defined here jail by including

#

# [SECTION_NAME]

# enabled = true



#

# in /etc/fail2ban/jail.local.

#

# Optionally you may override any other parameter (e.g. banaction,

# action, port, logpath, etc) in that section within jail.local



[ssh]



enabled  = true

port     = ssh

filter   = sshd

logpath  = /var/log/auth.log

maxretry = 6



[dropbear]



enabled  = false

port     = ssh

filter   = sshd

logpath  = /var/log/dropbear

maxretry = 6



# Generic filter for pam. Has to be used with action which bans all ports

# such as iptables-allports, shorewall

[pam-generic]



enabled  = false

# pam-generic filter can be customized to monitor specific subset of 'tty's

filter   = pam-generic

# port actually must be irrelevant but lets leave it all for some possible uses

port     = all

banaction = iptables-allports

port     = anyport

logpath  = /var/log/auth.log

maxretry = 6



[xinetd-fail]



enabled   = false

filter    = xinetd-fail

port      = all

banaction = iptables-multiport-log

logpath   = /var/log/daemon.log

maxretry  = 2





[ssh-ddos]



enabled  = false

port     = ssh

filter   = sshd-ddos

logpath  = /var/log/auth.log

maxretry = 6



#

# HTTP servers

#



[apache]



enabled  = false

port     = http,https

filter   = apache-auth

logpath  = /var/log/apache*/*error.log

maxretry = 6



# default action is now multiport, so apache-multiport jail was left

# for compatibility with previous (<0.7.6-2) releases

[apache-multiport]



enabled   = false

port      = http,https

filter    = apache-auth

logpath   = /var/log/apache*/*error.log

maxretry  = 6



[apache-noscript]



enabled  = false

port     = http,https

filter   = apache-noscript

logpath  = /var/log/apache*/*error.log

maxretry = 6



[apache-overflows]



enabled  = false

port     = http,https

filter   = apache-overflows

logpath  = /var/log/apache*/*error.log

maxretry = 2



#

# FTP servers

#



[vsftpd]



enabled  = false

port     = ftp,ftp-data,ftps,ftps-data

filter   = vsftpd

logpath  = /var/log/vsftpd.log

# or overwrite it in jails.local to be

# logpath = /var/log/auth.log

# if you want to rely on PAM failed login attempts

# vsftpd's failregex should match both of those formats

maxretry = 6





[proftpd]



enabled  = false

port     = ftp,ftp-data,ftps,ftps-data

filter   = proftpd

logpath  = /var/log/proftpd/proftpd.log

maxretry = 6





[pure-ftpd]



enabled  = false

port     = ftp,ftp-data,ftps,ftps-data

filter   = pure-ftpd

logpath  = /var/log/auth.log

maxretry = 6





[wuftpd]



enabled  = false

port     = ftp,ftp-data,ftps,ftps-data

filter   = wuftpd

logpath  = /var/log/auth.log

maxretry = 6





#

# Mail servers

#



[postfix]



enabled  = false

port     = smtp,ssmtp

filter   = postfix

logpath  = /var/log/mail.log





[couriersmtp]



enabled  = false

port     = smtp,ssmtp

filter   = couriersmtp

logpath  = /var/log/mail.log





#

# Mail servers authenticators: might be used for smtp,ftp,imap servers, so

# all relevant ports get banned

#



[courierauth]



enabled  = false

port     = smtp,ssmtp,imap2,imap3,imaps,pop3,pop3s

filter   = courierlogin

logpath  = /var/log/mail.log





[sasl]



enabled  = false

port     = smtp,ssmtp,imap2,imap3,imaps,pop3,pop3s

filter   = sasl

# You might consider monitoring /var/log/mail.warn instead if you are

# running postfix since it would provide the same log lines at the

# "warn" level but overall at the smaller filesize.

logpath  = /var/log/mail.log



[dovecot]



enabled = false

port    = smtp,ssmtp,imap2,imap3,imaps,pop3,pop3s

filter  = dovecot

logpath = /var/log/mail.log



# DNS Servers





# These jails block attacks against named (bind9). By default, logging is off

# with bind9 installation. You will need something like this:

#

# logging {

#     channel security_file {

#         file "/var/log/named/security.log" versions 3 size 30m;

#         severity dynamic;

#         print-time yes;

#     };

#     category security {

#         security_file;

#     };

# };

#

# in your named.conf to provide proper logging



# !!! WARNING !!!

#   Since UDP is connection-less protocol, spoofing of IP and imitation

#   of illegal actions is way too simple.  Thus enabling of this filter

#   might provide an easy way for implementing a DoS against a chosen

#   victim. See

#    http://nion.modprobe.de/blog/archives/690-fail2ban-+-dns-fail.html

#   Please DO NOT USE this jail unless you know what you are doing.

#[named-refused-udp]

#

#enabled  = false

#port     = domain,953

#protocol = udp

#filter   = named-refused

#logpath  = /var/log/named/security.log



[named-refused-tcp]



enabled  = false

port     = domain,953

protocol = tcp

filter   = named-refused

logpath  = /var/log/named/security.log

I have not changed anything inside except the local ips that it should ignore. So, after 4000 login attempts today, the ip has not been banned once, since the logs clearly show the person(s) is able to retry multiple times a minute still.

So I did sudo iptables -L and got :

libkmod: ERROR ../libkmod/libkmod.c:554 kmod_search_moddep: could not open moddep file '/lib/modules/3.18.7-v7+/modules.dep.bin'

iptables v1.4.14: can't initialize iptables table `filter': Table does not exist (do you need to insmod?)

Perhaps iptables or your kernel needs to be upgraded.

Hmm. I also checked the fail2ban log cat /var/log/fail2ban.log and got :

2015-05-22 12:05:43,083 fail2ban.server : INFO   Changed logging target to /var/log/fail2ban.log for Fail2ban v0.8.6

2015-05-22 12:05:43,086 fail2ban.jail   : INFO   Creating new jail 'ssh'

2015-05-22 12:05:43,088 fail2ban.jail   : INFO   Jail 'ssh' uses poller

2015-05-22 12:05:43,166 fail2ban.filter : INFO   Added logfile = /var/log/auth.log

2015-05-22 12:05:43,169 fail2ban.filter : INFO   Set maxRetry = 6

2015-05-22 12:05:43,173 fail2ban.filter : INFO   Set findtime = 600

2015-05-22 12:05:43,176 fail2ban.actions: INFO   Set banTime = 600

2015-05-22 12:05:43,385 fail2ban.jail   : INFO   Jail 'ssh' started

2015-05-22 12:05:43,467 fail2ban.actions.action: ERROR  iptables -N fail2ban-ssh

iptables -A fail2ban-ssh -j RETURN

iptables -I INPUT -p tcp -m multiport --dports ssh -j fail2ban-ssh returned 300

2015-05-22 19:42:34,799 fail2ban.server : INFO   Stopping all jails

2015-05-22 19:42:35,753 fail2ban.actions.action: ERROR  iptables -D INPUT -p tcp -m multiport --dports ssh -j fail2ban-ssh

iptables -F fail2ban-ssh

iptables -X fail2ban-ssh returned 300

2015-05-22 19:42:35,754 fail2ban.jail   : INFO   Jail 'ssh' stopped

2015-05-22 19:42:35,763 fail2ban.server : INFO   Exiting Fail2ban

2015-05-22 19:42:37,686 fail2ban.server : INFO   Changed logging target to /var/log/fail2ban.log for Fail2ban v0.8.6

2015-05-22 19:42:37,689 fail2ban.jail   : INFO   Creating new jail 'ssh'

2015-05-22 19:42:37,695 fail2ban.jail   : INFO   Jail 'ssh' uses Gamin

2015-05-22 19:42:37,824 fail2ban.filter : INFO   Added logfile = /var/log/auth.log

2015-05-22 19:42:37,827 fail2ban.filter : INFO   Set maxRetry = 6

2015-05-22 19:42:37,834 fail2ban.filter : INFO   Set findtime = 600

2015-05-22 19:42:37,837 fail2ban.actions: INFO   Set banTime = 600

2015-05-22 19:42:38,053 fail2ban.jail   : INFO   Jail 'ssh' started

2015-05-22 19:42:38,126 fail2ban.actions.action: ERROR  iptables -N fail2ban-ssh

iptables -A fail2ban-ssh -j RETURN

iptables -I INPUT -p tcp -m multiport --dports ssh -j fail2ban-ssh returned 300

I also checked fail2ban-regex against the auth.log, and it said over 4000 matches.

What is going on, is iptables broken in raspian? How to fix?

I found the fix for it, just do :

sudo rpi-update

That updated the firmware, the kernel version, and whatever else was needed to make iptables work, now my fail2ban is working fine.