Настраиваем VPS на Debian Ubuntu — часть 2

В первой части закончили на базовых настройках. Сейчас будем строить защиту доступа к нашему серверу.
Работать будем с fail2ban, устанавливаем:

$ aptitude update
$ aptitude install fail2ban

Далее перемещаемся в папку fail2ban:

$ cd /etc/fail2ban
$ nano jail.conf

И вносим нашу конфигурацию:

# 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: 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  = 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 = polling
#
# Destination email address used solely for the interpolations in
# jail.{conf,local} configuration files.
destemail = yourmail@mail.com
#
# 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_mw)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    = 29
filter    = sshd
logpath  = /var/log/auth.log
maxretry = 3
# 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 = 3
#
# 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
[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

Немного о конфиге:
[ssh]

enabled = true #включаем fail2ban правила для ssh
port = 29 #наш порт из предыдущей статьи
filter = sshd
logpath = /var/log/auth.log #куда пишем лог
maxretry = 3 #количество попыток ввода пароля до бана

[ssh-ddos]

enabled = true #включаем правила fail2ban при ddos на ssh
port = 29 #наш порт из предыдущей статьи
filter = sshd-ddos
logpath = /var/log/auth.log #куда пишутся логи
maxretry = 3 #количество запросов после которых fail2ban банит

В данном конфиге у нас уже настроена отправка извещений на почту при атаке на ssh (bruteforce ddos):

destemail = yourmail@mail.com

Вместо «yourmail@mail.com указать свою почту, после чего скопировать конфиг и правым кликом мышки вставить в открытый файл «jail.conf«.
После того, как редактирование файла конфигурации окончено, требуется перезапустить fail2ban:

$ sudo /etc/fail2bain restart

Ну, и можно проверять!

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