iptables router


susilaukiau klausimu, kaip pasidalinti internetu su kitu kompu turint dvi tinklo plokstes.

Taigi labai paprasta. Tikriausiai Jus naudojate standartini branduoliuka, del to ten bus visi branduolio moduliai ijungti.
Bet del viso ko galite pasibandyti, jei tingit, pereinam prie FW script’uko:

lsmod | grep ip_tables
lsmod | grep x_tables

Jei ten negauname rezultato:

~# lsmod | grep ip_tables
ip_tables 22042 3 iptable_filter,iptable_nat,iptable_mangle
x_tables 19073 11 ip_tables,iptable_filter,iptable_nat,ipt_MASQUERADE,xt_state,xt_tcpudp,ipt_LOG,ipt_REJECT,xt_limit,xt_multiport,iptable_mangle
~# lsmod | grep x_tables
x_tables 19073 11 ip_tables,iptable_filter,iptable_nat,ipt_MASQUERADE,xt_state,xt_tcpudp,ipt_LOG,ipt_REJECT,xt_limit,xt_multiport,iptable_mangle

Tuomet tiesiog pameginkime juos uzkrauti 🙂

modprobe ip_tables
modprobe x_tables

Ir issisaugoti automatiskai kraunamu moduliu sarase:

echo "ip_tables" >> /etc/modules
echo "x_tables" >> /etc/modules



Taigi beliko tik pasirasyti FW script’uka (P.S. pas jus gal neveiks conntrack –ctstate , tai keiskite state –state):

export PATH="/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin"
# apsirasom IPTABLES
# Isvalom esamas taisykles
$IPTABLES -t nat -F
$IPTABLES -t nat -X
# Local interface:
# External (Internetas) interface:
# jei Jusu IP statinis siulau nurotyri rankiniu budu:
# Pas mane dinaminis IP todel as ji gaudau per skriptuka... Jei Jusu statinis IP, uzkomentuokite sia eilute
INTER_IP=`ip addr show eth0 | grep "inet " | awk '{print $2}' | cut -f1 -d\/`
# Ijungiu FORWARDinima:
echo "1" > /proc/sys/net/ipv4/ip_forward
# Tinklas LAN'ui
# Jei neveikia -m conntrack --ctstate ...
# Kuriu naujas/papildomas grandis:
# Leidziu VISKA is VIDAUS
# Accept PING, kartais naudinga, patikrint ar jusu servas gyvas
$IPTABLES -A INPUT -p icmp --icmp-type echo-request -j ACCEPT
$IPTABLES -A OUTPUT -p icmp --icmp-type echo-reply -j ACCEPT
# Leidziu uzmegstas sesijas
# Visus kas kreipiasi i 22 poerta is isores, loginam :)
$IPTABLES -A INPUT -d $INTER_IP --proto tcp --dport 22 -j LOGDROP
# SSH SERVER internete pasiekiamas per 212 porta, nors realiai kito LAN'e esancio kompo ( 22 portas
# $IPTABLES -t nat -A PREROUTING -i $INTER_IP --proto tcp --dport 212 -j DNAT --to
# rdp forward i win xp winxp XP masina
$IPTABLES -t nat -A PREROUTING -i $INTER_IP --proto tcp --dport 3389 -j DNAT --to
$IPTABLES -A LOGDROP2 -j LOG --log-prefix "DROPPED " --log-level 4 --log-ip-options --log-tcp-options --log-tcp-sequence
$IPTABLES -A LOGDROP -m limit --limit 1/second --limit-burst 10 -j LOGDROP2
$IPTABLES -A LOGDROP -m limit --limit 2/minute --limit-burst 1 -j LOG --log-prefix "LIMITED " --log-level 4
##### Po sios komandos, isijungia FIREWALL! ATSARGIAI!
logger -p info -t syslog "firewall updated"
exit 0

Na va pas jus toks minimalus, noob’iskas firewall’as 🙂

External links

Gentoo iptables for newbies

skanaus 🙂

(!COPY!) How to Hack wifi (and how to avoid being hacked) WEP/WPA/WPA2 (!COPY!)

This guide is meant to show how easy it is to hack wireless networks if the proper security measures are not in place. First I will show how to hack a WEP or WPA/WPA2 Network and then I will give tips on how to avoid getting hacked.

This is important information in our techno-savy culture. If your wireless network is compromised you can be liable for any illegal activity on it. There are numerous stories of child pornographers and black-hat hackers using other peoples wireless networks.

NOTE: Hacking your neighbors or anyone else’s Wifi without their permission is ILLEGAL. Be smart!
Step 1What you Need

-A Computer. (A Laptop works best)

-A Wireless Card capable of packet injection.
-If your laptop wireless card can’t do packet injection you can purchase a wireless adapter such as the Netgear WG111 v2 for around $8-$12 on eBay.

-A Live installation of BackTrack either on a CD or USB stick.
-BackTrack 5 Can be found Here
-Create a Live USB Install Here
Step 2Hack WEP

WEP is the predecessor of WPA and has been hacked for the past 5+ years yet people continue to use it. With the instructions below we can crack WEP in under 15 minutes.

You can crack WEP from the command line but there is an easy GUI interface in backtrack which makes it a much less painful experience for those who are scared of command prompts.

1. Boot into BackTrack

2. Click on the Backtrack applications menu -> Backtrack -> Exploitation tools -> Wireless exploitation -> WLAN Exploitation -> gerix-wifi-cracker-ng (This will open up the GUI interface seen in the picture).

3. Go to the configuration menu and select the wireless interface wlan0
-Click on Enable/Disable Monitor Mode (this will put the wireless card into monitor mode).
-Select the newly created mon0 interface.

4. Now click on the WEP tab at the top of the window.
-Click on “Start sniffing and logging” and leave the terminal open.
-Once the wireless network you want to crack* shows up (it has to be WEP encryption of course) select the WEP Attacks (with clients). *note that the PWR has to be high enough to work so the closer you can get, the better.
-There you click on “Associate with AP using fake auth”, wait a few seconds and click on “ARP request replay”.

5. Once the Data number reaches over 10,000 you are ready to try (if the data is coming fast wait until 20 or 30,000 to be safe) and crack the key, but don’t close any windows yet.
-Go to the cracking tab and click on “Aircrack-ng – Decrypt WEP password” under Wep Cracking.

It will take a few seconds to minutes to crack the password and then you are good to go.
Step 3Hack WPA/WPA2

At least WPA and WPA2 are safe right? Wrong. WPA and WPA2 are both crackable but the time it takes to crack depends on the strength of their password.

-Boot into BackTrack
-Open up Konsole which is a command line utility built into BackTrack. It is the Black Box in the Lower-Left Hand Corner (See Image).
We will now be entering the following commands into the command line noted by Bold as well as explanations as to what they do:

-The following commands stop the wireless interface so you can change your mac address, this is important because your mac address is a unique identifier so faking one is a good idea if you are accessing a network you don’t have permission to. (which by the way I wholly condemn)

airmon-ng stop wlan0
ifconfig wlan0 down
macchanger –mac 00:11:22:33:44:55 wlan0
airmon-ng start wlan0

-Now we will put the airodump-ng tool into monitor mode, this will allow us to see all of the wireless networks around us (See the first Picture).

airodump-ng mon0

Now choose the network you want to hack and take note of the BSSID, and the Channel it is one as well as the ESSID. The PWR has to be fairly high to be able to hack it, this is determined by how close you are to the wireless router. The closer you are, the better.

Once you have chosen the wireless network enter the following into the terminal:
This will write capture packets and put them into the “filename” file, we are trying to capture the handshake between the router and wireless connection which will give us the key we need to crack.

airodump-ng mon0 –channel * –bssid **:**:**:**:**:** -w filename

The following step is optional but is highly recommended as it will speed up the process a great deal.

Once “WPA handshake: **:**:**:**:**:**” appears in the top right-hand corner we can move on. If you are having trouble getting the WPA handshake to occur then do step 4.

aireplay-ng -0 1 -a **:**:**:**:**:** -c **:**:**:**:**:** mon0

What this step (4) does is it deauthorizes a wireless connection and trie to re-establish it so it will generate a new handshake to capture. This step ends once you have captured the handshake.

aircrack-ng –w wordlist.lst -b **:**:**:**:**:** filename.cap

Step 5 is now trying to crack the password in “filename.cap” using a list of words, here called “wordlist.lst” you can download a good 200 million word dictionary here (128MB but unzipped is 800MB).

Your computer has to compute the hash value of every password in that list but a computer can go through those 200 million passwords in 6-12 hours.


If the password isn’t found in the dictionary you can try and brute-force the password with this command: (Note this could take a very long time depending on their password strength).

/pentest/password/jtr/john –stdout –incremental:all | aircrack-ng -b **:**:**:**:**:** -w – filename.cap
Step 4Secure Your Own Wireless Network

Hopefully you gained some insight into how to not get your own wireless connection hacked:

1. Use WPA2 (WPA2-AES) if available and by all means never use WEP.
2. Don’t base your password on a dictionary word. The next section focuses on passwords in general.
3. In your router settings you can usually hide your ESSID (the name of the wireless network) this will add a small layer of security.
4. In your router there is probably a mac-address filtering service where you can specify the mac addresses that are allowed to connect. This will make sure that only your approved devices can connect to your network. (obviously a problem though if you have a guest over and wants to connect to your Wifi).
Step 5Passwords

You have to have good passwords in this day and age. If not your credit card information, your personal information and identity are available to those who want to use it and abuse it. Here are some guidelines to coming up with a secure password:

1. At least 8 characters.
2. At least one number, letter and special character ie: $ # % ^ @ !
3. NOT based on a dictionary word
4. Multiple transitions: ie: aaa111aaa111 not aaaa11111.

How can I remember these passwords?

Come up with a word such as: calculus and substitute numbers and other characters for letters ie: c@1cu1u$
This is still based on a dictionary word though so you should still make it harder such as appending something to the end or beginning.

I also highly recommend using a different password for every website, how can you do this easily? Remember random variables in algebra? Have a random variable in your password that is based on the website or some other information.

IE: XpasswordY where the first X is the last letter of the website name and the last Y is the first letter of the website name:

So the Instructables website password would be SpasswordI or your Facebook password would be KpasswordF and your Hotmail password will be LpasswordH.

It might seem like a lot but it’s worth the time to prevent the potential theft of your money, identity and your life ruined.

External Link:

How to Hack wifi (and how to avoid being hacked) WEP/WPA/WPA2

SNMP reikšmės

snmpwalk -v2c -O n -c local . #- uptime
snmpwalk -v2c -O n -c local . #- uptime
snmpwalk -v2c -O n -c local . # – TCP listenning ir uzmegstos sesijos.
snmpwalk -v2c -O n -c local . #- Total disk space
snmpwalk -v2c -O n -c local . #- Disk Used
snmpwalk -v2c -O n -c local . #- Disk Reads ir writes: Linux only
snmpwalk -v2c -O n -c local . #- Total size of the disk/partion (kBytes): Linux Only
snmpwalk -v2c -O n -c local . #- Available space on the disk: Linux Only
snmpwalk -v2c -O n -c local . #- Used space on the disk: Linux Only
snmpwalk -v2c -O n -c local . #- Percentage of space used on disk: Linux Only
snmpwalk -v2c -O n -c local . #- Percentage of inodes used on disk: Linux Only
snmpwalk -v2c -O n -c local . #- Procesai veikiantys
snmpwalk -v2c -O n -c local . #- Procesai maks

Išorinė medžiaga: oidview.com HOST RESOURCES MIB

NTP (Network Time Protocol) ir ntpdate


Dažnai susiduriate su problema, kad jūsų kompiuterio laikrodis rodo vieną laiką, namie esantys laikrodžiai rodo kitą laiką, kiek šiuo metu laiko, sužinoti, tampa ganėtinai sunku, anksčiau buvo telefono numeris, kuriuo paskambinus buvo pasakomas laikas… Jei turite interneto prieigą, tai galite užeiti į kokį puslapį… Bet ar ten rodo gerą laiką? Net jei ir puslapis yra iš Lietuvos ir Lietuvių kalba, ir skirtas Lietuvos auditoriai (lankytojams) vistiek, puslapio rodomas laikas gali sutapti su Jūsų kompiuterio rodomu laiku, nes galimi du variantai, Jūsų kompiuteris rodo tikslų laiką, arba Tiesiog puslapis nesivargina, o um parodo Jūsų kompiuteryje rodomą laiką… 🙂 Dauguma tinklapių kūrėju mano, kad Jūsų kompiuteris rodo Jums priimtiną laiką… Kaipgi dabar užtikrinti, kad Jūsų kompiuteris taip elgtųsi… Paprasta, Jei naudojame Linux:

ntpdate ntpdate.lpic.lt

Jei Windows, atidarykite komandinę eilutę, Paspaudus „Windows“ prekinį ženklą atsiradusio meniu apačioje, įvesties laukely, įraūykite cmd Jei tokio įvesties laukelio nėra, spauskite Run ir atsiradusiame lange įrašykite cmd. Dabar beliko pridėti:

w32tm /config /syncfromflags:manual /manualpeerlist:ntpdate.lpic.lt,0.pool.ntp.org,1.pool.ntp.org,2.pool.ntp.org
net time /setsntp:"ntpdate.lpic.lt 0.pool.ntp.org 1.pool.ntp.org" Kažkaip taip… 🙂