No Fail2Ban, como alterar o número da porta SSH?

Question

No meu servidor, a porta ssh não é o padrão 22. Defini uma diferente. Se eu configurar o fail2ban, ele será capaz de detectar essa porta? Como posso dizer para verificar essa porta em vez da porta 22?

A saída de iptables -L -v -n :

 Chain fail2ban-ssh (1 references)
 pkts bytes target     prot opt in     out     source               destination                                                                                         
    0     0 DROP       all  --  *      *       119.235.2.158        0.0.0.0/0                                                                                           
    0     0 RETURN     all  --  *      *       0.0.0.0/0            0.0.0.0/0                                                                                           

 Chain fail2ban-ssh-ddos (0 references)
 pkts bytes target     prot opt in     out     source               destination

A saída do status do serviço iptables:

iptables: unrecognized service

Verão de fail2ban-regex /var/log/auth.log /etc/fail2ban/filter.d/sshd.conf :

Summary
=======

Addresses found:
[1]
[2]
[3]
    113.59.222.240 (Wed Mar 21 18:24:47 2012)
    113.59.222.240 (Wed Mar 21 18:24:52 2012)
    119.235.14.153 (Wed Mar 21 21:52:53 2012)
    113.59.222.21 (Thu Mar 22 07:50:44 2012)
    176.9.57.203 (Fri Mar 23 19:34:29 2012)
    176.9.57.203 (Fri Mar 23 19:34:42 2012)
    113.59.222.56 (Sat Mar 31 14:23:52 2012)
    113.59.222.56 (Sat Mar 31 14:24:05 2012)
    119.235.14.183 (Mon Apr 02 20:49:13 2012)
    119.235.14.168 (Sat Apr 21 09:58:56 2012)
    119.235.2.158 (Wed Apr 25 13:11:03 2012)
    119.235.2.158 (Wed Apr 25 13:11:40 2012)
    119.235.2.158 (Wed Apr 25 13:11:43 2012)
    119.235.2.158 (Wed Apr 25 13:11:47 2012)
    119.235.2.158 (Wed Apr 25 13:12:49 2012)
    119.235.2.158 (Wed Apr 25 13:12:52 2012)
    119.235.2.158 (Wed Apr 25 13:12:55 2012)
    119.235.2.158 (Wed Apr 25 13:12:58 2012)
    119.235.2.158 (Wed Apr 25 13:13:02 2012)
    119.235.2.158 (Wed Apr 25 13:13:04 2012)
    119.235.2.158 (Wed Apr 25 13:13:25 2012)
    119.235.2.158 (Wed Apr 25 13:19:18 2012)
    119.235.2.158 (Wed Apr 25 13:19:52 2012)
    119.235.2.158 (Wed Apr 25 13:19:55 2012)
    119.235.2.158 (Wed Apr 25 13:19:55 2012)
    119.235.2.158 (Wed Apr 25 13:19:58 2012)
    119.235.2.158 (Wed Apr 25 13:20:02 2012)
    119.235.2.158 (Wed Apr 25 13:20:05 2012)
    119.235.2.158 (Wed Apr 25 13:40:16 2012)
[4]
[5]
    119.235.2.158 (Wed Apr 25 13:11:38 2012)
    119.235.2.158 (Wed Apr 25 13:12:46 2012)
    119.235.2.158 (Wed Apr 25 13:19:49 2012)
[6]
    119.235.2.155 (Wed Mar 21 13:13:30 2012)
    113.59.222.240 (Wed Mar 21 18:24:43 2012)
    119.235.14.153 (Wed Mar 21 21:52:51 2012)
    176.9.57.203 (Fri Mar 23 19:34:26 2012)
    119.235.2.158 (Wed Apr 25 13:19:15 2012)
[7]
[8]
[9]
[10]

Date template hits:
1169837 hit(s): MONTH Day Hour:Minute:Second
0 hit(s): WEEKDAY MONTH Day Hour:Minute:Second Year
0 hit(s): WEEKDAY MONTH Day Hour:Minute:Second
0 hit(s): Year/Month/Day Hour:Minute:Second
0 hit(s): Day/Month/Year Hour:Minute:Second
0 hit(s): Day/Month/Year Hour:Minute:Second
0 hit(s): Day/MONTH/Year:Hour:Minute:Second
0 hit(s): Month/Day/Year:Hour:Minute:Second
0 hit(s): Year-Month-Day Hour:Minute:Second
0 hit(s): Day-MONTH-Year Hour:Minute:Second[.Millisecond]
0 hit(s): Day-Month-Year Hour:Minute:Second
0 hit(s): TAI64N
0 hit(s): Epoch
0 hit(s): ISO 8601
0 hit(s): Hour:Minute:Second
0 hit(s): <Month/Day/Year@Hour:Minute:Second>

Success, the total number of match is 37

However, look at the above section 'Running tests' which could contain important
information.

O jail.conf :

    # 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 <[email protected]>
#
# $Revision: 281 $
#

# The DEFAULT allows a global definition of the options. They can be override
# in each jail afterwards.

[DEFAULT]

# "ignoreip" can be an IP address, a CIDR mask or a DNS host
ignoreip = 127.0.0.1
bantime  = 14400
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 = polling

#
# 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 overriden 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

#
# 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]

# ban & send an e-mail with whois report to the destemail.
action_mw = %(banaction)s[name=%(__name__)s, port="%(port)s", protocol="%(protocol)s]
              %(mta)s-whois[name=%(__name__)s, dest="%(destemail)s", protocol="%(protocol)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]
               %(mta)s-whois-lines[name=%(__name__)s, dest="%(destemail)s", logpath=%(logpath)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 = 4

# 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 = true
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

 [nginx-auth]
 enabled = true
 filter = nginx-auth
 action = iptables-multiport[name=NoAuthFailures, port="http,https"]
 logpath = /var/log/nginx*/*error*.log
 bantime = 600 # 10 minutes
 maxretry = 6

 [nginx-login]
 enabled = true
 filter = nginx-login
 action = iptables-multiport[name=NoLoginFailures, port="http,https"]
 logpath = /var/log/nginx*/*access*.log
 bantime = 600 # 10 minutes
 maxretry = 6

 [nginx-badbots]
 enabled  = true
 filter = apache-badbots
 action = iptables-multiport[name=BadBots, port="http,https"]
 logpath = /var/log/nginx*/*access*.log
 bantime = 86400 # 1 day
 maxretry = 1

 [nginx-noscript]
 enabled = true
 action = iptables-multiport[name=NoScript, port="http,https"]
 filter = nginx-noscript
 logpath = /var/log/nginx*/*access*.log
 maxretry = 6
 bantime  = 86400 # 1 day

 [nginx-proxy]
 enabled = true
 action = iptables-multiport[name=NoProxy, port="http,https"]
 filter = nginx-proxy
 logpath = /var/log/nginx*/*access*.log
 maxretry = 0
 bantime  = 86400 # 1 day


#
# 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


[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/warn.log instead
# if you are running postfix. See http://bugs.debian.org/507990
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 connectionless protocol, spoofing of IP and immitation
#   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

Acabei de notar um erro no fail2ban log :

2012-04-25 14:57:29,359 fail2ban.actions.action: ERROR iptables -N fail2ban-ssh-ddos

    

Answer 1

O Fail2Ban usa o arquivo /etc/fail2ban/jail.local e procura pela seção [ssh] , você pode alterar a porta para lá.

[ssh]
enabled  = true
port     = ssh

Você pode alterar o valor port para qualquer número inteiro positivo.

Se não estiver funcionando e você quiser procurar mais, dê uma olhada em /etc/fail2ban/jail.conf , deve haver algo como:

 logpath = /var/log/auth.log

Isso é o que o fail2ban usa para detectar logins falsos.

Se não estiver funcionando corretamente, você pode tentar algumas coisas para identificar o problema. Comece verificando se está instalado:

dpkg -l |grep fail   

Verifique se o serviço está sendo executado:

/etc/init.d/fail2ban status 

Verifique se sua cadeia SSH está configurada:

sudo fail2ban-client status  

Verifique o arquivo de log:

fail2ban-regex /var/log/auth.log /etc/fail2ban/filter.d/sshd.conf

Verifique sua data / hora:

date && tail -2 /var/log/auth.log

(Você deve primeiro obter a data, seguido pelas últimas linhas em auth.log . Se você ainda não conseguir identificar o erro, adicione seu arquivo de configuração à sua postagem.

    

Answer 2

O fail2ban detectará as tentativas de login com o conteúdo do log. O fail2ban não usa portas para detecção, apenas para bloquear.
Para bloquear a porta certa, você tem que informar ao fail2ban qual deles para configurar corretamente o iptable. Em /etc/fail2ban/jail.local :

[ssh]
enabled  = true
port     = ssh   <-- just modify this with your port    port = 1234

Outro método é bloquear tudo dos hosts ofensivos. Então o iptable irá remover todos os pacotes, não apenas os ssh.
No início de /etc/fail2ban/jail.local :

banaction = iptables-multiport     <-- regular blocking (one or several ports)
banaction = iptables-allports      <-- block everything

Com iptables-allports você não precisa se preocupar com as portas. Apenas deixe os padrões.

    

Answer 3

Em suma: se você alterou o número da porta ssh, você tem que adicioná-lo no arquivo jail.conf !

Por exemplo: (eu uso SSH, SFTP na porta 1234)

em jail.conf :

[ssh]

enabled  = true

port     = ssh,sftp,1234

filter   = sshd

logpath  = /var/log/auth.log

maxretry = 6

    

Answer 4

Eu sei que isso não está respondendo estritamente a pergunta, mas de qualquer forma ...

Como outra forma de resolver o problema, considere manter as portas padrão na configuração do servidor e, em seguida, fazer o NAT no roteador.

Por exemplo, na minha configuração eu também não uso porta padrão para ssh do lado de fora, mas minha configuração de servidor é padrão para ssh (assim como é para ftp, vpn etc) eu apenas abro portas não-padrão o roteador e enviá-los para a porta padrão.

Essa maneira de fazer isso me poupa bastante tempo ao configurar minha configuração.