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FIREWALL. Konsep Firewall. salah satu lapisan pertahanan yang mengatur hubungan komputer dengan dunia luar melalui interogasi setiap traffic, packet, dan port-port yang diatur dengan rule-rule yang ada Dilakukan dengan cara : Menyaring membatasi menolak.

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konsep firewall
Konsep Firewall
  • salah satu lapisan pertahanan yang mengatur hubungan komputer dengan dunia luar melalui interogasi setiap traffic, packet, dan port-port yang diatur dengan rule-rule yang ada
  • Dilakukan dengan cara :

Menyaring

membatasi

menolak

hubungan /kegiatan suatu segmen pada jaringan pribadi dengan jaringan luar yang bukan merupakan ruang lingkupnya

konfigurasi sederhana

Boleh lewat mbak ? Nih surat-suratnya

Anak kecil ga boleh keluar.. sudah malam

Firewall

Konfigurasi Sederhana

pc (jaringan local) <==> firewall <==> internet (jaringan lain)

firewall topologi basic two interface firewall no dmz
Firewall Topologi :Basic Two-interface Firewall (no DMZ)
  • Connects to ISP using DSL, Cable Modem, ISDN, Dial-up, …
  • Provides for “Internet Connection Sharing” of a single public IP address for a local network using SNAT/Masquerading
firewall topologi three interface firewall with dmz
Firewall Topologi :Three-interface Firewall (with DMZ)
  • Provides internet connection sharing of one or more public IP addresses.
  • Had a DMZ containing servers that are exposed to the internet.
  • If a server is hacked, the Firewall and the Local network aren’t compromised.
tipe firewall
Tipe Firewall

Berdasarkan mekanisme cara kerja :

  • Packet Filtering
    • Memfilter paket berdasarkan sumber, tujuan dan atribut paket (filter berdasar IP dan Port). Yang difilter IP, TCP, UDP, and ICMP headers and port number
  • Application Level
    • Biasa disebut proxy firewall, filter bisa berdasarkan content paket
  • Circuit Level Gateway
    • Filter berdasarkan sesi komunikasi, dengan pengawasan sesi handshake.
    • Terdapat sesi NEW/ESTABLISH
  • Statefull Multilayer Inspection Firewall
    • Kombinasi dari ketiga tipe firewall diatas
circuit level stateful inspection firewalls
Circuit Level / Stateful Inspection Firewalls
  • Default Behavior

Permit connections initiated by an internal host

Deny connections initiated by an external host

Can change default behavior with ACL

  • For DMZ Implementation

Automatically Accept Connection Attempt

Internet

Router

Automatically Deny Connection Attempt

dmz configuration

internet

Firewall

Web Server

DMZ Configuration
  • Place web servers in the “DMZ” network
  • Only allow web ports (TCP ports 80 and 443)
dmz configuration1

Mas ..yang merah gak boleh lewat lho

internet

Firewall

Web Server

DMZ Configuration
  • Don’t allow web servers access to your network
  • Allow local network to manage web servers (SSH)
  • Don’t allow servers to connect to the Internet
  • Patching is not convenient
iptables1
IPTABLES
  • iptables is a networking administration command-line tool on Linux which interfaces to the kernel-provided Netfilter modules. This allows for stateless and stateful firewalls and NAT. It is useful to think of IPtables as being a specialised firewall-creation programming language.
prinsip kerja iptables
Prinsip Kerja iptables
  • Paket masuk diproses berdasarkan tujuan :
    • Destination IP untuk Firewall  masuk proses input
    • Destination IP bukan untuk firewall tapi diteruskan  masuk proses FORWARD
  • Selanjutnya dicocokkan berdasarkan tabel policy yang dipunyai firewall apakah di-accept atau di-drop
prinsip kerja firewall
Prinsip Kerja Firewall

Firewall Machine

sintaks iptables
Sintaks IPTABLES
  • Opsi
    • -A, menambah satu aturan baru ditempatkan pada posisi terakhir

iptables –A INPUT …

    • -D, menghapus rule

iptables –D INPUT 1

iptables –D –s 202.154.178.2 …

    • -I, menambah aturan baru penempatan bisa disisipkan sesuai nomor

iptables –I INPUT 3 –s 202.154.178.2 –j ACCEPT

    • -R, mengganti rule

iptables –R INPUT 2 –s –s 202.154.178.2 –j ACCEPT

    • -F, menghapus seluruh rule

iptables –F

    • -L, melihat Rule

iptables -L

parameter
Parameter
  • -p [!] protocol, protokol yang akan dicek

Iptables –A INPUT –p tcp …

  • -s [!] address/[mask], memeriksa kecocokan sumber paket

Iptables –A INPUT –s 10.252.44.145 …

  • -d [!] address/[mask], memerika kecocokan tujuan paket

Iptables –A INPUT –d 202.154.178.2 …

  • -j target, menentukan nasib paket, target misal ACCEPT/DROP/REJECT

Iptables –A INPUT –d 202.154.178 –j DROP

  • -i [!] interface_name, identifikasi kartu jaringan tempat masuknya data

Iptables –A INPUT –i etho ….

  • -o [!] interface_name, identifikasi kartu jaringan tempat keluarnya paket

Iptables –A OUTPUT –o eth1 ….

match iptables
Match iptables
  • --mac address, matching paket berdasarkan nomor MAC Address

Iptables –m mac –mac-address 44:45:53:54:00:FF

  • Multiport, mendifinisikan banyak port

Iptables –m multiport –source-port 22,25,110,80 –j ACCEPT

  • State, mendefinisikan state dari koneksi

Iptables –A INPUT –m state –state NEW, ESTABLISH –j ACCEPT

target jump iptables
Target/Jump iptables
  • ACCEPT, setiap paket langsung diterima

Iptables –A INPUT –p tcp –dport 80 –j ACCEPT

  • DROP, paket datang langsung dibuang

Iptables –A INPUT –p tcp –dport 21 –j DROP

  • REJECT, paket yang ditolak akan dikirimi pesan ICMP error

Iptables –A INPUT –p tcp –dport 21 –j REJECT

  • SNAT, sumber paket dirubah, biasanya yang memiliki koneksi internet

Iptables –t nat –A POSROUTING –p tcp –o eth0 –j SNAT –to-source 202.154.178.2

  • DNAT, merubah tujuan alamat paket. Biasanya jika server alamat Ipnya lokal, supaya internet bisa tetap akses diubah ke publik

Iptables –t nat –A PREPROUTING –p tcp –d 202.154.178.2 –dport 80 –j DNAT –to-destination 192.168.1.1

  • MASQUERADE, untuk berbagi koneksi internet dimana no_ipnya terbatas, sebagai mapping ip lokal ke publik

Iptables –t nat –A POSTROUTING –o eth0 –dport 80 –j MASQUERADE

  • REDIRECT, sigunakan untuk transparent proxy

Ipatbles –t nat –A PREROUTING –p tcp –d 0/0 –dport 80 –j REDIRECT –to-port 8080

  • LOG, melakukan pencatatan terhadap aktifitas firewall kita, untuk melihat bisa dibuka /etc/syslog.conf

Iptables –A FORWARD –j LOG –log-level-debug

Iptables –A FORWARD –j LOG –log-tcp-options

firewall option
Firewall Option
  • # Mengeluarkan Modul-modul Iptables
  • /sbin/modprobe ip_tables
  • /sbin/modprobe ip_conntrack
  • /sbin/modprobe iptable_filter
  • /sbin/modprobe iptable_mangle
  • /sbin/modprobe iptable_nat
  • /sbin/modprobe ipt_LOG
  • /sbin/modprobe ipt_limit
  • /sbin/modprobe ipt_state
  • /sbin/modprobe ip_conntrack_ftp
  • /sbin/modprobe ip_conntrack_irc
  • /sbin/modprobe ip_nat_ftp
  • /sbin/modprobe ip_nat_irc
menghapus rule iptables
Menghapus Rule iptables
  • # Menghapus aturan iptables

$IPTABLES -F

$IPTABLES -t nat -F

$IPTABLES -t mangle -F

  • # Menghapus nama kolom yg dibuat manual

$IPTABLES -X

$IPTABLES -t nat -X

$IPTABLES -t mangle -X

forward
Forward
  • iptables –t nat –A POSTROUTING –s IP_number -d 0/0 –j MASQUERADE
  • #iptables –A FORWARD –p icmp –s 0/0 –d 0/0 –j ACCEPT
  • Iptables –A INPUT –p imcp –s 0/0 –j DROP
  • #iptables –A FORWARD –i eth1 –o eth0 –p icmp –s 10.252.105.109 –d 192.168.108.5 –j ACCEPT
  • #iptables –A FORWARD –s 192.168.108.5/24 –d 0/0 –p tcp --dport ftp, -j REJECT
studi kasus 1
Studi Kasus 1
  • Bangun Jaringan sendiri
  • Install web server dan FTP Server pada jaringan Internet (10.252.105.xxx)
  • Setting memblok PC2 dan PC3 supaya tidak bisa mengakses web dan FTP
setting komputer router pc1
Setting Komputer Router PC1
  • Setting Ip_forward

#echo 1> /proc/sys/net/ipv4/ip_forward

  • Setting menggunakan NAT

iptables –t nat –A POSTROUTING –o eth0 –s IP_number -d 0/0 –j MASQUERADE

  • Setting IP

Eth0  192.168.105.109 Bcast:192.168.105.255 Mask:255.255.255.0

Eth0:1  192.168.108.1 Bcast:192.168.108.255 Mask:255.255.255.0

  • Setting Routing

# route add default gw 192.168.105.1

setting setiap client
Setting Setiap Client
  • PC2

Setting IP

inet addr:192.168.108.10 Bcast:192.168.108.255 Mask:255.255.255.0

  • PC3

Setting IP

inet addr:192.168.108.5 Bcast:192.168.108.255 Mask:255.255.255.0

  • PC4

Setting IP

inet addr:192.168.108.20 Bcast:192.168.108.255 Mask:255.255.255.0

  • Setting Gateway untuk PC2, PC3 & PC4

route add default gw 192.168.108.1

test konektifitas
Test Konektifitas
  • Router PC 1

ping 192.168.108.10, ping 192.168.108.5, ping 192.168.108.20, ping 192.168.105.1, ping 202.154.187.4

  • PC 2

ping 192.168.105.109, ping 192.168.108.5, ping 192.168.108.20, ping 192.168.105.1, ping 202.154.187.4

  • PC 3

ping 192.168.105.109, ping 192.168.108.10, ping 192.168.108.20, ping 192.168.105.1, ping 202.154.187.4

  • PC 4

ping 192.168.105.109, ping 192.168.108.10, ping 192.168.108.5, ping 192.168.105.1, ping 202.154.187.4

rule firewall
Rule Firewall
  • Setting memblok PC2 dan PC3 supaya tidak bisa mengakses web dan FTP

#iptables –A FORWARD –m state –state NEW –m multiport –s 192.168.108.5/24 –d 0/0 –p tcp –dport www, -j REJECT

#iptables –A FORWARD –m state –state NEW –m multiport –s 192.168.108.5/24 –d 0/0 –p tcp –dport ftp, -j REJECT

#iptables –restore, iptables save

studi kasus 2 dmz
Studi Kasus 2 - DMZ
  • eth0 with 192.168.1.1 private IP address - Internal LAN ~ Desktop system
  • eth1 with 202.54.1.1 public IP address - WAN connected to ISP router
  • eth2 with 192.168.2.1 private IP address - DMZ connected to Mail / Web / DNS and other private servers
routing traffic between public and dmz server
Routing traffic between public and DMZ server
  • To set a rule for routing all incoming SMTP requests to a dedicated Mail server at IP address 192.168.2.2 and port 25, network address translation (NAT) calls a PREROUTING table to forward the packets to the proper destination.
  • This can be done with appropriate IPTABLES firewall rule to route traffic between LAN to DMZ and public interface to DMZ. For example, all incoming mail traffic from internet (202.54.1.1) can be send to DMZ mail server (192.168.2.2) with the following iptables prerouting rule (assuming default DROP all firewall policy):
routing traffic between public and dmz server1
Routing traffic between public and DMZ server

### end init firewall .. Start DMZ stuff ####

# forward traffic between DMZ and LAN

iptables -A FORWARD -i eth0 -o eth2 -m state --state NEW,ESTABLISHED,RELATED -j ACCEPT

iptables -A FORWARD -i eth2 -o eth0 -m state --state ESTABLISHED,RELATED -j ACCEPT

# forward traffic between DMZ and WAN servers SMTP, Mail etc

iptables -A FORWARD -i eth2 -o eth1 -m state --state ESTABLISHED,RELATED -j ACCEPT

iptables -A FORWARD -i eth1 -o eth2 -m state --state NEW,ESTABLISHED,RELATED -j ACCEPT

# Route incoming SMTP (port 25 ) traffic to DMZ server 192.168.2.2

iptables -t nat -A PREROUTING -p tcp -i eth1 -d 202.54.1.1 --dport 25 -j DNAT --to-destination 192.168.2.2

# Route incoming HTTP (port 80 ) traffic to DMZ server load balancer IP 192.168.2.3

iptables -t nat -A PREROUTING -p tcp -i eth1 -d 202.54.1.1 --dport 80 -j DNAT --to-destination 192.168.2.3

# Route incoming HTTPS (port 443 ) traffic to DMZ server reverse load balancer IP 192.168.2.4

iptables -t nat -A PREROUTING -p tcp -i eth1 -d 202.54.1.1 --dport 443 -j DNAT --to-destination 192.168.2.4

### End DMZ .. Add other rules ###

slide34
Where,
  • -i eth1 : Wan network interface
  • -d 202.54.1.1 : Wan public IP address
  • --dport 25 : SMTP Traffic
  • -j DNAT : DNAT target used set the destination address of the packet with --to-destination
  • --to-destination 192.168.2.2: Mail server ip address (private IP)
multi port redirection
Multi port redirection
  • You can also use multiport iptables module to matches a set of source or destination ports. Up to 15 ports can be specified. For example, route incoming HTTP (port 80 ) and HTTPS ( port 443) traffic to WAN server load balancer IP 192.168.2.3:
  • iptables -t nat -A PREROUTING -p tcp -i eth1 -d 202.54.1.1 -m multiport --dport 80,443 -j DNAT --to-destination 192.168.2.3
shorewall2
Shorewall
  • Shorewall

tools for building a firewall

variable : interfaces, zones, rules

  • Konfigurasi Shorewall terdapat pada direktori /etc/shorewall, yang minimal terdiri dari zone, interfaces, rule, policy, dan shorewall.conf.
slide41
Zone
  • Shorewall membagi jaringan menjadi beberapa zone yang dideskripsikan di /etc/shorewall/zones
  • diibaratkan komputer terdiri dari dua interfaces maka akan kita buat menjadi zone net dan zone loc, sehingga konfigurasi /etc/shorewall/zones sbb:
  • #ZONE TYPE OPTIONS IN OUT
  • # OPTIONS OPTIONS
  • fw firewall
  • net ipv4
  • loc ipv4
    • Zone net adalah zona internet
    • zone loc adalah zona lokal
    • Zona fw mendeskripsikan mesin firewall itu sendiri.
  • Penamaan zona terserah kepada kita.
interfaces
Interfaces
  • Kemudian kita definisikan interfaces apa saja yang akan kita terapkan zona tadi pada /etc/shorewall/interfaces, konfigurasinya kira-kira seperti :

#ZONE INTERFACE BROADCAST OPTIONS

net eth0 detect norfc1918

loc eth1 detect

rules
Rules
  • Rules dalah kebijakan yang akan mengatur setiap koneksi yang masuk ke firewall, contoh konfigurasi /etc/shorewall/rules :
  • #ACTION SOURCE DEST PROTO DEST PORT(S)
  • Ping/ACCEPT loc:192.168.0.1 $FW
  • ACCEPT $FW all icmp
  • Web/ACCEPT all $FW
  • SSH/ACCEPT loc:192.168.0.1 $FW
policy
Policy
  • Policy adalah kebijakan umum yang diterapkan untuk hubungan masing-masing zone jika nanti tidak ada rule yang mendeskripsikannya , misalkan :
  • #SOURCE DEST POLICY LOG LEVEL LIMIT:BURST
  • loc net ACCEPT
  • net all DROP info
  • all all REJECT info
slide49
Untuk instalasi berbasis debian biasanya file /etc/shorewall kosong, file-file rule default dapat di copy dari /usr/share/doc/shorewall/default-config serta contoh-contoh konfigurasi juga ada pada /usr/share/doc/shorewall/examples
installation
Installation
  • Remove

:~# apt-get remove portmap

:~# apt-get remove nfs-common

:~# apt-get remove pidentd

installation1
Installation
  • Install Shorewall

:~# apt-get install shorewall

  • Install documentation

:~# apt-get install shorewall-doc

configuration
Configuration
  • goto shorewall directory

:~# cd /etc/shorewall

  • look inside

:/etc/shorewall# ls

configuration1
Configuration
  • Change /etc/default/shorewall from

startup=0

to

startup=1

  • # vim /etc/default/shorewall

change the startup

activate the firewall
Activate the firewall
  • do this

# /etc/init.d/shorewall start

  • watch your firewall

# iptables –nL | less

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