Minütlich versuchter Zugriff auf Debian

M

motte

Member
Hallo Leute


Ein bekannter von mir hat zurzeit massive Probleme mit flood artigen Zugriffen auf sein Debian Server bei Hetzner.

Das Problem besteht erst seit 4 Tagen so massiv

Was er bis jetzt unternommen hat :

SSH Port Verlegt
Root user mit Keyfile versehen
fail2ban eingerichtet ( Config weiter unten )
viele ip´s mit iptables dauerhaft gesperrt
Apache ausgeschaltet da er dachte es liegt an dem
das gleiche für ftp

Was kann er denn noch machen das das aufhört?
Apache und ftp sollten aber gern beide laufen.

Es läuft kein mail oder mysql Dienst

Code: 
# 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.
#
# Comments: use '#' for comment lines and ';' for inline comments
#
# To avoid merges during upgrades DO NOT MODIFY THIS FILE
# and rather provide your changes in /etc/fail2ban/jail.local
#

# 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. Fail2ban will not
# ban a host which matches an address in this list. Several addresses can be
# defined using space separator.
ignoreip = 127.0.0.1/8

# External command that will take an tagged arguments to ignore, e.g. <ip>,
# and return true if the IP is to be ignored. False otherwise.
#
# ignorecommand = /path/to/command <ip>
ignorecommand =

# "bantime" is the number of seconds that a host is banned.
bantime  = 86400

# A host is banned if it has generated "maxretry" during the last "findtime"
# seconds.
findtime = 600
maxretry = 3

# "backend" specifies the backend used to get files modification.
# Available options are "pyinotify", "gamin", "polling" and "auto".
# This option can be overridden in each jail as well.
#
# pyinotify: requires pyinotify (a file alteration monitor) to be installed.
#            If pyinotify is not installed, Fail2ban will use auto.
# gamin:     requires Gamin (a file alteration monitor) to be installed.
#            If Gamin is not installed, Fail2ban will use auto.
# polling:   uses a polling algorithm which does not require external libraries.
# auto:      will try to use the following backends, in order:
#            pyinotify, gamin, polling.
backend = auto

# "usedns" specifies if jails should trust hostnames in logs,
#   warn when reverse DNS lookups are performed, or ignore all hostnames in logs
#
# yes:   if a hostname is encountered, a reverse DNS lookup will be performed.
# warn:  if a hostname is encountered, a reverse DNS lookup will be performed,
#        but it will be logged as a warning.
# no:    if a hostname is encountered, will not be used for banning,
#        but it will be logged as info.
usedns = warn

#
# Destination email address used solely for the interpolations in
# jail.{conf,local} configuration files.
destemail = root@localhost

#
# Name of the sender for mta actions
sendername = Fail2Ban

# Email address of the sender
sender = fail2ban@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", sendername="%(sendername)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", sendername="%(sendername)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

[dropbear]

enabled  = false
port     = ssh
filter   = dropbear
logpath  = /var/log/auth.log
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


# Here we use blackhole routes for not requiring any additional kernel support
# to store large volumes of banned IPs

[ssh-route]

enabled = false
filter = sshd
action = route
logpath = /var/log/sshd.log
maxretry = 6

# Here we use a combination of Netfilter/Iptables and IPsets
# for storing large volumes of banned IPs
#
# IPset comes in two versions. See ipset -V for which one to use
# requires the ipset package and kernel support.
[ssh-iptables-ipset4]

enabled  = false
port     = ssh
filter   = sshd
banaction = iptables-ipset-proto4
logpath  = /var/log/sshd.log
maxretry = 6

[ssh-iptables-ipset6]

enabled  = false
port     = ssh
filter   = sshd
banaction = iptables-ipset-proto6
logpath  = /var/log/sshd.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

[apache-modsecurity]

enabled  = false
filter   = apache-modsecurity
port     = http,https
logpath  = /var/log/apache*/*error.log
maxretry = 2

[apache-nohome]

enabled  = false
filter   = apache-nohome
port     = http,https
logpath  = /var/log/apache*/*error.log
maxretry = 2

# Ban attackers that try to use PHP's URL-fopen() functionality
# through GET/POST variables. - Experimental, with more than a year
# of usage in production environments.

[php-url-fopen]

enabled = false
port    = http,https
filter  = php-url-fopen
logpath = /var/www/*/logs/access_log

# A simple PHP-fastcgi jail which works with lighttpd.
# If you run a lighttpd server, then you probably will
# find these kinds of messages in your error_log:
#   ALERT – tried to register forbidden variable ‘GLOBALS’
#   through GET variables (attacker '1.2.3.4', file '/var/www/default/htdocs/index.php')

[lighttpd-fastcgi]

enabled = false
port    = http,https
filter  = lighttpd-fastcgi
logpath = /var/log/lighttpd/error.log

# Same as above for mod_auth
# It catches wrong authentifications

[lighttpd-auth]

enabled = false
port    = http,https
filter  = suhosin
logpath = /var/log/lighttpd/error.log

[nginx-http-auth]

enabled = false
filter  = nginx-http-auth
port    = http,https
logpath = /var/log/nginx/error.log

# Monitor roundcube server

[roundcube-auth]

enabled  = false
filter   = roundcube-auth
port     = http,https
logpath  = /var/log/roundcube/userlogins


[sogo-auth]

enabled  = false
filter   = sogo-auth
port     = http, https
# without proxy this would be:
# port    = 20000
logpath  = /var/log/sogo/sogo.log


#
# 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  = true
port     = ftp,ftp-data,ftps,ftps-data
filter   = proftpd
logpath  = /var/log/proftpd/proftpd.log
maxretry = 4


[pure-ftpd]

enabled  = false
port     = ftp,ftp-data,ftps,ftps-data
filter   = pure-ftpd
logpath  = /var/log/syslog
maxretry = 6


[wuftpd]

enabled  = false
port     = ftp,ftp-data,ftps,ftps-data
filter   = wuftpd
logpath  = /var/log/syslog
maxretry = 6


#
# Mail servers
#

[postfix]

enabled  = false
port     = smtp,ssmtp,submission
filter   = postfix
logpath  = /var/log/mail.log


[couriersmtp]

enabled  = false
port     = smtp,ssmtp,submission
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,submission,imap2,imap3,imaps,pop3,pop3s
filter   = courierlogin
logpath  = /var/log/mail.log


[sasl]

enabled  = false
port     = smtp,ssmtp,submission,imap2,imap3,imaps,pop3,pop3s
filter   = postfix-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,submission,imap2,imap3,imaps,pop3,pop3s
filter  = dovecot
logpath = /var/log/mail.log

# To log wrong MySQL access attempts add to /etc/my.cnf:
# log-error=/var/log/mysqld.log
# log-warning = 2
[mysqld-auth]

enabled  = false
filter   = mysqld-auth
port     = 3306
logpath  = /var/log/mysqld.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

[freeswitch]

enabled  = false
filter   = freeswitch
logpath  = /var/log/freeswitch.log
maxretry = 10
action   = iptables-multiport[name=freeswitch-tcp, port="5060,5061,5080,5081", protocol=tcp]
           iptables-multiport[name=freeswitch-udp, port="5060,5061,5080,5081", protocol=udp]

[ejabberd-auth]

enabled  = false
filter   = ejabberd-auth
port     = xmpp-client
protocol = tcp
logpath  = /var/log/ejabberd/ejabberd.log


# Multiple jails, 1 per protocol, are necessary ATM:
# see https://github.com/fail2ban/fail2ban/issues/37
[asterisk-tcp]

enabled  = false
filter   = asterisk
port     = 5060,5061
protocol = tcp
logpath  = /var/log/asterisk/messages

[asterisk-udp]

enabled  = false
filter	 = asterisk
port     = 5060,5061
protocol = udp
logpath  = /var/log/asterisk/messages


# Jail for more extended banning of persistent abusers
# !!! WARNING !!!
#   Make sure that your loglevel specified in fail2ban.conf/.local
#   is not at DEBUG level -- which might then cause fail2ban to fall into
#   an infinite loop constantly feeding itself with non-informative lines
[recidive]

enabled  = false
filter   = recidive
logpath  = /var/log/fail2ban.log
action   = iptables-allports[name=recidive]
           sendmail-whois-lines[name=recidive, logpath=/var/log/fail2ban.log]
bantime  = 604800  ; 1 week
findtime = 86400   ; 1 day
maxretry = 5

# See the IMPORTANT note in action.d/blocklist_de.conf for when to
# use this action
#
# Report block via blocklist.de fail2ban reporting service API
# See action.d/blocklist_de.conf for more information
[ssh-blocklist]

enabled  = false
filter   = sshd
action   = iptables[name=SSH, port=ssh, protocol=tcp]
           sendmail-whois[name=SSH, dest="%(destemail)s", sender="%(sender)s", sendername="%(sendername)s"]
           blocklist_de[email="%(sender)s", apikey="xxxxxx", service="%(filter)s"]
logpath  = /var/log/sshd.log
maxretry = 20


# consider low maxretry and a long bantime
# nobody except your own Nagios server should ever probe nrpe
[nagios]
enabled  = false
filter   = nagios
action   = iptables[name=Nagios, port=5666, protocol=tcp]
           sendmail-whois[name=Nagios, dest="%(destemail)s", sender="%(sender)s", sendername="%(sendername)s"]
logpath  = /var/log/messages     ; nrpe.cfg may define a different log_facility
maxretry = 1

Code: 
# Fail2Ban main configuration file
#
# Comments: use '#' for comment lines and ';' (following a space) for inline comments
#
# Changes:  in most of the cases you should not modify this
#           file, but provide customizations in fail2ban.local file, e.g.:
#
# [Definition]
# loglevel = 4
#

[Definition]

# Option: loglevel
# Notes.: Set the log level output.
#         1 = ERROR
#         2 = WARN
#         3 = INFO
#         4 = DEBUG
# Values: [ NUM ]  Default: 1
#
loglevel = 3

# Option: logtarget
# Notes.: Set the log target. This could be a file, SYSLOG, STDERR or STDOUT.
#         Only one log target can be specified.
#         If you change logtarget from the default value and you are
#         using logrotate -- also adjust or disable rotation in the
#         corresponding configuration file
#         (e.g. /etc/logrotate.d/fail2ban on Debian systems)
# Values: [ STDOUT | STDERR | SYSLOG | FILE ]  Default: STDERR
#
logtarget = /var/log/fail2ban.log

# Option: socket
# Notes.: Set the socket file. This is used to communicate with the daemon. Do
#         not remove this file when Fail2ban runs. It will not be possible to
#         communicate with the server afterwards.
# Values: [ FILE ]  Default: /var/run/fail2ban/fail2ban.sock
#
socket = /var/run/fail2ban/fail2ban.sock

# Option: pidfile
# Notes.: Set the PID file. This is used to store the process ID of the
#         fail2ban server.
# Values: [ FILE ]  Default: /var/run/fail2ban/fail2ban.pid
#
pidfile = /var/run/fail2ban/fail2ban.pid
 
Es sind immer Zugriffe auf ssh sowie auf http das verzeichniss ist Passwort geschützt.

log Auszug muss er mir erst geben
 
Kontinuierliches SSH-BruteForcing ist normal. Siehe hier:

http://securehoney.net/stats.html

Am besten nur SSH-Keys zur Authentifizierung verwenden.

Fail2ban auch für die Webserverlogfiles. Bruteforceattacken kosten ab einer gewissen Menge auch ordentlich Performance, wenn ständig PHP-Seiten aufgerufen werden und da zu wenig Leistungsreserven auf dem Server vorhanden sind.

Dazu noch fail2ban mit erhöhten Sperrzeiten für Wiederholungstäter(Google: f2bloop).

Ansonsten noch den Traffic etwas beobachten und durch iptables ggf. vorher schon unübliche Verbindungen filtern.
 
Last edited by a moderator:
Aufgrund der Indizien, die hier zu finden sind, scheint der Server nur mangelhaft bzw. sorglos konfiguriert zu sein. Entsprechend bin ich angenehm überrascht, dass dieser "Angriff" überhaupt bemerkt wurde.

Abgesehen davon ist der "Angriff" laut Log-File nicht besonders schwer. Mit den oben beschriebenen Maßnahmen sollte da nichts passieren und auch die Leistung der Servers sollte nicht beeinträchtigt sein. Entsprechendes Rauschen kommt bei öffentlichen Diensten immer vor.
 
@Tolive : was sollte er denn verbessern ?

immer liest man das man was verbessern soll oder das system mangelhaft konfiguriert sein.

Ein paar stichpunkte wären hilfreich wenn möglich .
 
Also wenn das auth.log von einer Zeit stammt als fail2ban schon lief dann scheint mir die jail config ein wenig zu lasch, manche IPs sind ja dutzend-fach zu finden.
Bei mir persönlich ist nach 3 Fehlversuchen innerhalb 1 Stunde Schicht im Schacht.

Ausserdem sollte, falls es wirklich sehr viele IPs sind, die Sperrung besser per route als per iptables bewerkstelligt werden....denn wenn jeder Request erst mal hunderte von Firewall-Regeln durchlaufen muss verursacht dies einen ziemlichen lag durch i/o-waits.
 
In der jail.conf:

Code: 
maxretry = 3
findtime = 3600


In der fail2ban sshd.conf:
Code: 
action = route
 
Kann mir einer sagen wie eine optimale jail.conf aus sehen sollte ?

Sowie was alles auf true steh soll / muss?
 
You must log in or register to reply here.
Back
Top