Today i’ve found a crash in kblogger. But i was unable to get a valid backtrace because kblogger is a KUniqueApplication .

A KUniqueApplication will fork(): the parent process exits, the child continues.

So if you want debug a application child of KUniqueApplication you must launch

gdb –args your_application –nofork

(thank to pinotree for the suggestion)

Scopo di questo piccolo howto è installare e configurare una VPN (Virtual Private Network) da usare come tunnel per connettersi in modo “sicuro” ad internet quando si è in giro per il mondo (o in università!:P) e si usano connessioni wireless/wired poco affidabili.

Iniziamo installando il pacchetto openvpn sul nostro server (io uso ubuntu).

apt-get install openvpn

Copiamo i tools necessari alla generazione dei certificati e delle chiavi in una dir a nostro piacere (usare /tmp è poco paranoico! :P)

cp /usr/share/doc/openvpn/easy-rsa /tmp -r

cd /tmp

Editiamo il file vars e lo avviamo

. vars

Avviandolo abbiamo impostato alcune variabili d’ambiente necessarie per l’esecuzione degli altri script

NOTA: va eseguito con il ‘.’ ovvero “. vars”!!!

ora creiamo i nostro root key e certificato con il quale faremo poi il sign delle varie chiavi di server e client.

./build-ca

verranno creati i file ca.crt e ca.key nella KEY_DIR impostata nel file vars.

creiamo i DIFFIE-HELLMAN PARAMETERS (necessary for the server end of a SSL/TLS connection).

./build-dh

creiamo chiave e certificato per server e client

./build-key-server server

scrivendo “server” o qualunque cosa ci ricordi che quello è il server alla voce common name.

Creiamo ora le chiavi per i client

./build-key client1

scrivendo “client1″ o qualunque cosa ci ricordi che quello è il client n°1 alla voce common name.

Nota: se abbiamo + client possiamo creare + chiavi con buid-key.

Abbiamo creato cosi i seguenti files:

Filename Needed By Purpose Secret

ca.crt server + all clients Root CA certificate NO

ca.key key signing machine only Root CA key YES

dh{n}.pem server only Diffie Hellman parameters NO

server.crt server only Server Certificate NO

server.key server only Server Key YES

client1.crt client1 only Client1 Certificate NO

client1.key client1 only Client1 Key YES

Creiaamo ora le directory CA, SERVER in /etc/openvpn

mkdir /etc/openvpn/CA

mkdir /etc/openvpn/SERVER

e spostiamo i file delle chiavi e dei certificati attenendoci alla tabella riportata sopra.

Avremo cosi i seguenti file nelle seguenti cartelle:

CA:

ca.crt ca.key

SERVER:

dh1024.pem server.crt server.key

Copiamo ora sul client i file:

ca.crt

client1.crt

client1.key

(Magari usando sftp o una via “sicura” proteggendo il .key da occhi indiscreti!)

Creiamo i file server.conf sul host server e client.conf sugli host client

Usiamo come file di configurazione per client e server i file di esempi standard che potete trovare qui sotto o in /usr/share/doc/openvpn/examples.

Ricordando che # e ; son caratteri che commentano la riga.

--------------------SERVER-------------------------------------

root@dharma:/etc/openvpn# cat server.conf

#################################################

# Sample OpenVPN 2.0 config file for #

# multi-client server. #

# #

# This file is for the server side #

# of a many-clients one-server #

# OpenVPN configuration. #

# #

# OpenVPN also supports #

# single-machine single-machine #

# configurations (See the Examples page #

# on the web site for more info). #

# #

# This config should work on Windows #

# or Linux/BSD systems. Remember on #

# Windows to quote pathnames and use #

# double backslashes, e.g.: #

# "C:\\Program Files\\OpenVPN\\config\\foo.key" #

# #

# Comments are preceded with '#' or ';' #

#################################################

# Which local IP address should OpenVPN

# listen on? (optional)

local 192.168.1.2

# Which TCP/UDP port should OpenVPN listen on?

# If you want to run multiple OpenVPN instances

# on the same machine, use a different port

# number for each one. You will need to

# open up this port on your firewall.

;port 5002

lport 5002

# TCP or UDP server?

proto tcp

;proto udp

# "dev tun" will create a routed IP tunnel,

# "dev tap" will create an ethernet tunnel.

# Use "dev tap0" if you are ethernet bridging

# and have precreated a tap0 virtual interface

# and bridged it with your ethernet interface.

# If you want to control access policies

# over the VPN, you must create firewall

# rules for the the TUN/TAP interface.

# On non-Windows systems, you can give

# an explicit unit number, such as tun0.

# On Windows, use "dev-node" for this.

# On most systems, the VPN will not function

# unless you partially or fully disable

# the firewall for the TUN/TAP interface.

;dev tap

dev tun

# Windows needs the TAP-Win32 adapter name

# from the Network Connections panel if you

# have more than one. On XP SP2 or higher,

# you may need to selectively disable the

# Windows firewall for the TAP adapter.

# Non-Windows systems usually don't need this.

;dev-node MyTap

# SSL/TLS root certificate (ca), certificate

# (cert), and private key (key). Each client

# and the server must have their own cert and

# key file. The server and all clients will

# use the same ca file.

#

# See the "easy-rsa" directory for a series

# of scripts for generating RSA certificates

# and private keys. Remember to use

# a unique Common Name for the server

# and each of the client certificates.

#

# Any X509 key management system can be used.

# OpenVPN can also use a PKCS #12 formatted key file

# (see "pkcs12" directive in man page).

ca /etc/openvpn/CA/ca.crt

cert /etc/openvpn/SERVER/server.crt

key /etc/openvpn/SERVER/server.key # This file should be kept secret

# Diffie hellman parameters.

# Generate your own with:

# openssl dhparam -out dh1024.pem 1024

# Substitute 2048 for 1024 if you are using

# 2048 bit keys.

dh /etc/openvpn/SERVER/dh1024.pem

# Configure server mode and supply a VPN subnet

# for OpenVPN to draw client addresses from.

# The server will take 10.8.0.1 for itself,

# the rest will be made available to clients.

# Each client will be able to reach the server

# on 10.8.0.1. Comment this line out if you are

# ethernet bridging. See the man page for more info.

server 10.8.0.0 255.255.255.0

# Maintain a record of client virtual IP address

# associations in this file. If OpenVPN goes down or

# is restarted, reconnecting clients can be assigned

# the same virtual IP address from the pool that was

# previously assigned.

ifconfig-pool-persist ipp.txt

# Configure server mode for ethernet bridging.

# You must first use your OS's bridging capability

# to bridge the TAP interface with the ethernet

# NIC interface. Then you must manually set the

# IP/netmask on the bridge interface, here we

# assume 10.8.0.4/255.255.255.0. Finally we

# must set aside an IP range in this subnet

# (start=10.8.0.50 end=10.8.0.100) to allocate

# to connecting clients. Leave this line commented

# out unless you are ethernet bridging.

;server-bridge 10.8.0.4 255.255.255.0 10.8.0.50 10.8.0.100

# Push routes to the client to allow it

# to reach other private subnets behind

# the server. Remember that these

# private subnets will also need

# to know to route the OpenVPN client

# address pool (10.8.0.0/255.255.255.0)

# back to the OpenVPN server.

;push "route 192.168.10.0 255.255.255.0"

;push "route 192.168.20.0 255.255.255.0"

# To assign specific IP addresses to specific

# clients or if a connecting client has a private

# subnet behind it that should also have VPN access,

# use the subdirectory "ccd" for client-specific

# configuration files (see man page for more info).

# EXAMPLE: Suppose the client

# having the certificate common name "Thelonious"

# also has a small subnet behind his connecting

# machine, such as 192.168.40.128/255.255.255.248.

# First, uncomment out these lines:

;client-config-dir ccd

;route 192.168.40.128 255.255.255.248

# Then create a file ccd/Thelonious with this line:

# iroute 192.168.40.128 255.255.255.248

# This will allow Thelonious' private subnet to

# access the VPN. This example will only work

# if you are routing, not bridging, i.e. you are

# using "dev tun" and "server" directives.

# EXAMPLE: Suppose you want to give

# Thelonious a fixed VPN IP address of 10.9.0.1.

# First uncomment out these lines:

;client-config-dir ccd

;route 10.9.0.0 255.255.255.252

# Then add this line to ccd/Thelonious:

# ifconfig-push 10.9.0.1 10.9.0.2

# Suppose that you want to enable different

# firewall access policies for different groups

# of clients. There are two methods:

# (1) Run multiple OpenVPN daemons, one for each

# group, and firewall the TUN/TAP interface

# for each group/daemon appropriately.

# (2) (Advanced) Create a script to dynamically

# modify the firewall in response to access

# from different clients. See man

# page for more info on learn-address script.

;learn-address ./script

# If enabled, this directive will configure

# all clients to redirect their default

# network gateway through the VPN, causing

# all IP traffic such as web browsing and

# and DNS lookups to go through the VPN

# (The OpenVPN server machine may need to NAT

# the TUN/TAP interface to the internet in

# order for this to work properly).

# CAVEAT: May break client's network config if

# client's local DHCP server packets get routed

# through the tunnel. Solution: make sure

# client's local DHCP server is reachable via

# a more specific route than the default route

# of 0.0.0.0/0.0.0.0.

;push "redirect-gateway"

# Certain Windows-specific network settings

# can be pushed to clients, such as DNS

# or WINS server addresses. CAVEAT:

# http://openvpn.net/faq.html#dhcpcaveats

;push "dhcp-option DNS 10.8.0.1"

;push "dhcp-option WINS 10.8.0.1"

# Uncomment this directive to allow different

# clients to be able to "see" each other.

# By default, clients will only see the server.

# To force clients to only see the server, you

# will also need to appropriately firewall the

# server's TUN/TAP interface.

;client-to-client

# Uncomment this directive if multiple clients

# might connect with the same certificate/key

# files or common names. This is recommended

# only for testing purposes. For production use,

# each client should have its own certificate/key

# pair.

#

# IF YOU HAVE NOT GENERATED INDIVIDUAL

# CERTIFICATE/KEY PAIRS FOR EACH CLIENT,

# EACH HAVING ITS OWN UNIQUE "COMMON NAME",

# UNCOMMENT THIS LINE OUT.

;duplicate-cn

# The keepalive directive causes ping-like

# messages to be sent back and forth over

# the link so that each side knows when

# the other side has gone down.

# Ping every 10 seconds, assume that remote

# peer is down if no ping received during

# a 120 second time period.

keepalive 10 120

# For extra security beyond that provided

# by SSL/TLS, create an "HMAC firewall"

# to help block DoS attacks and UDP port flooding.

#

# Generate with:

# openvpn --genkey --secret ta.key

#

# The server and each client must have

# a copy of this key.

# The second parameter should be '0'

# on the server and '1' on the clients.

;tls-auth ta.key 0 # This file is secret

# Select a cryptographic cipher.

# This config item must be copied to

# the client config file as well.

;cipher BF-CBC # Blowfish (default)

;cipher AES-128-CBC # AES

;cipher DES-EDE3-CBC # Triple-DES

# Enable compression on the VPN link.

# If you enable it here, you must also

# enable it in the client config file.

comp-lzo

# The maximum number of concurrently connected

# clients we want to allow.

;max-clients 100

# It's a good idea to reduce the OpenVPN

# daemon's privileges after initialization.

#

# You can uncomment this out on

# non-Windows systems.

;user nobody

;group nogroup

# The persist options will try to avoid

# accessing certain resources on restart

# that may no longer be accessible because

# of the privilege downgrade.

persist-key

persist-tun

# Output a short status file showing

# current connections, truncated

# and rewritten every minute.

status openvpn-status.log

# By default, log messages will go to the syslog (or

# on Windows, if running as a service, they will go to

# the "\Program Files\OpenVPN\log" directory).

# Use log or log-append to override this default.

# "log" will truncate the log file on OpenVPN startup,

# while "log-append" will append to it. Use one

# or the other (but not both).

;log openvpn.log

;log-append openvpn.log

# Set the appropriate level of log

# file verbosity.

#

# 0 is silent, except for fatal errors

# 4 is reasonable for general usage

# 5 and 6 can help to debug connection problems

# 9 is extremely verbose

verb 4

# Silence repeating messages. At most 20

# sequential messages of the same message

# category will be output to the log.

;mute 20

——————–CLIENT————————

$ cat client.conf

##############################################

# Sample client-side OpenVPN 2.0 config file #

# for connecting to multi-client server. #

# #

# This configuration can be used by multiple #

# clients, however each client should have #

# its own cert and key files. #

# #

# On Windows, you might want to rename this #

# file so it has a .ovpn extension #

##############################################

# Specify that we are a client and that we

# will be pulling certain config file directives

# from the server.

client

# Use the same setting as you are using on

# the server.

# On most systems, the VPN will not function

# unless you partially or fully disable

# the firewall for the TUN/TAP interface.

;dev tap

dev tun

# Windows needs the TAP-Win32 adapter name

# from the Network Connections panel

# if you have more than one. On XP SP2,

# you may need to disable the firewall

# for the TAP adapter.

;dev-node MyTap

# Are we connecting to a TCP or

# UDP server? Use the same setting as

# on the server.

proto tcp

;proto udp

# The hostname/IP and port of the server.

# You can have multiple remote entries

# to load balance between the servers.

remote gnuton.homeunix.org 5002

;remote my-server-2 1194

# Choose a random host from the remote

# list for load-balancing. Otherwise

# try hosts in the order specified.

;remote-random

# Keep trying indefinitely to resolve the

# host name of the OpenVPN server. Very useful

# on machines which are not permanently connected

# to the internet such as laptops.

resolv-retry infinite

# Most clients don't need to bind to

# a specific local port number.

nobind

# Downgrade privileges after initialization (non-Windows only)

;user nobody

;group nogroup

# Try to preserve some state across restarts.

persist-key

persist-tun

# If you are connecting through an

# HTTP proxy to reach the actual OpenVPN

# server, put the proxy server/IP and

# port number here. See the man page

# if your proxy server requires

# authentication.

;http-proxy-retry # retry on connection failures

;http-proxy [proxy server] [proxy port #]

# Wireless networks often produce a lot

# of duplicate packets. Set this flag

# to silence duplicate packet warnings.

;mute-replay-warnings

# SSL/TLS parms.

# See the server config file for more

# description. It's best to use

# a separate .crt/.key file pair

# for each client. A single ca

# file can be used for all clients.

ca ca.crt

cert client1.crt

key client1.key

# Verify server certificate by checking

# that the certicate has the nsCertType

# field set to "server". This is an

# important precaution to protect against

# a potential attack discussed here:

# http://openvpn.net/howto.html#mitm

#

# To use this feature, you will need to generate

# your server certificates with the nsCertType

# field set to "server". The build-key-server

# script in the easy-rsa folder will do this.

;ns-cert-type server

# If a tls-auth key is used on the server

# then every client must also have the key.

;tls-auth ta.key 1

# Select a cryptographic cipher.

# If the cipher option is used on the server

# then you must also specify it here.

;cipher x

# Enable compression on the VPN link.

# Don't enable this unless it is also

# enabled in the server config file.

comp-lzo

# Set log file verbosity.

verb 4

# Silence repeating messages

;mute 20

-----------------------------------------------------------------

NOTA: Salvando queste configurazioni in /etc/openvpn/ lo script /etc/init.d/openvpn avvierà automaticamente il demone al riavvio della macchina utilizzando tali configurazioni.

Per testare le nostre configurazione, lanciamo sul server e poi sul client

openvpn –config /etc/openvpn/server.conf

openvpn –config /etc/openvpn/client.conf

se nei log stampati a schermo leggiamo qualcosa del tipo

Sun Mar 2 10:15:53 2008 us=254390 Initialization Sequence Completed

sia lato client che server è tutto ok

controlliamo anche se l’interfaccia tun0 è up (se è tutto ok, dovrebbe essere certamente “su”)

#ifconfig tun0

tun0 Link encap:UNSPEC HWaddr 00-00-00-00-00-00-00-00-00-00-00-00-00-00-00-00

inet addr:10.8.0.6 P-t-P:10.8.0.5 Mask:255.255.255.255

UP POINTOPOINT RUNNING NOARP MULTICAST MTU:1500 Metric:1

RX packets:0 errors:0 dropped:0 overruns:0 frame:0

TX packets:0 errors:0 dropped:0 overruns:0 carrier:0

collisions:0 txqueuelen:100

RX bytes:0 (0.0 b) TX bytes:0 (0.0 b)

Ricordandoci che 10.8.0.1 è l’ip del client.

proviamo a pingare il server

# ping 10.8.0.1

se pinga è tutto ok!
Ora che abbiamo creato un tunnel punto a punto tra server e client, se si vuole che il client usi la VPN per “navigare in internet” usando la connessione internet del server (magari quella di casa nostra o del nostro ufficio), abilitiamo il nostro server VPN a funzionare da gateway.

1) Modifichiamo lo script del firewall in /etc/init.d aggiungendo righe tipo queste:

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

iptables -t nat -A POSTROUTING -o eth0 -j MASQUERADE

dove eth0 è l’intefaccia dalla quale il mio gateway VPN “riceve la connessione internet” secondo lo schema:

[internet][router]eth0[OpenVPN Server]tun0tun0[OpenVPN client]

Nel caso in cui non avessimo nessuno script che setti le regole del firewall sul server (male) possiamo anche in maniera molto, ma molto grezza inserire le precedenti linee nel file /etc/init.d/openvpn in modo tale che il server al boot possa fare da gateway per le connessioni internet delle macchine che si collegano via vpn.

2) Decommentiamo la linea ‘push “redirect-gateway”‘ nel server.conf

Ora per testare il corretto funzionamento, posso usare l’utility tracepath o route;

se tutto è andato bene vedremo che i nostri pacchetti saranno instradati via openVPN

$ tracepath www.google.it

1: 10.8.0.6 (10.8.0.6) 0.654ms pmtu 1500

1: 10.8.0.1 (10.8.0.1) 90.794ms

2: 192.168.1.1 (192.168.1.1) 92.217ms

3: 192.168.1.1 (192.168.1.1) asymm 2 90.773ms pmtu 1492

se quacosa è andato storto

1) tracepath è muto, dobbiamo configurare il NAT sul nostro openVPN server

2) tracepath ritorna qualcosa di simile:

$ tracepath www.google.it

1: 192.168.1.2 (192.168.1.2) 0.64ms

2: 192.168.1.1 (192.168.1.1)

In questo caso stiamo ancora usando il default gateway della nostra sottorete, percui tutti i pacchetti sono instradati verso internet per mezzo del nostro router e non via VPN.

Probabilmente abbiamo dimenticato di modificare il server.conf, aggiungendo/decommentando la riga push “redirect-gateway”.

Nota: Nel caso avessimo delle regole di firewalling restrittive i pacchetti icmp di tracepath potrebbero essere bloccati, in tal caso tracepath nn ci da nulla.

Possiamo però ugualmente controllare la tabella di routing del kernel del nostro client con il comando “route”

Questo è tutto. Spero di esser stato chiaro e di non aver saltato passaggi o commesso errori.

Per qualunque cosa, usate commentate il post!

Nota: Se siete dei possessori dei fantastici Nokia Internet Tablet (come me), vi ricordo che openvpn è presente nei repository ufficiali!!

Buona navigazione “sicura”!

Per maggiori informazioni vi rimando al sito ufficiale di openvpn.

I’ve bought some GameBoy color Cartridges via eBay.. i’m really happy, but my pokemon gold cartridge doesn’t work properly.
It doesn’t save.
So I’ve opened my cartridge and i’ve measured the volts of the internal battery and…. surprise! My multimeter signs 0 Volts.. Yeah!
I’ve got to change it!
Note: The GameBoy Cartridge uses a Litio battery model CR 1616.

If you want to watch Divx or other videos encoded with proprietary codecs, you need to install win32/64 codec pack!
Add this line to /etc/apt/source.list
sudo wget http://www.medibuntu.org/sources.list.d/gutsy.list -O /etc/apt/sources.list.d/medibuntu.list
and then run this
wget -q http://packages.medibuntu.org/medibuntu-key.gpg -O- | sudo apt-key add - && sudo apt-get update
so you can install now!
apt-get install w32-codecs non-free-codecs libxine1-ffmpeg
(or w64-codecs)
Now you can watch your Videos with Kaffeine!

Ho inserito la versione aggiornata della mia mini guida ad SVN per principianti. La potete scaricare in formato ODT da qui

The rt2×00 is a new driver based on 802.11 framework of intel. In my linux box with Linksys wusb54g work very fine; With this driver you can add more interfaces (wlan1, wlan2…ecc) other wlan0… and you can set different mode for each interfaces; For example you can set wlan0 in managed mode and wlan1 in monitor mode, but remeber that all the interfaces must have the same mac address (if you use macchange..) and same channel (freq.) (if you using a single device!!).
Note: this is really different from rt2570 legacy driver, and remeber that you can set the mode of the interface only if it’s down (Es: ifconfig wlan0 down && iwconfig wlan mode managed && ifconfig wlan0 up).
That is all! Have a fun with the new driver, thanks to rt2×00 developers! =)

Finalmente un po di tempo per provare la nuova kubuntu edgy knot; ancora in fase di beta testing, ma a mio parere gia abbastanza stabile.
Manca ancora di pacchetti universe, come kdevelop3 che comunque possiamo utilizzare ed installare… a volte però richiedono alcune modifiche;
Infatti se proviamo a dare un build di un progetto Kde, avremo conflitti di autoconf (richiede una versione 2.5.x mentre è installata la 2.60) e automake;
Per risolvere questo problema si può semplicemente eliminare la directory admin dal progetto creato e sostituirla con quella che possiamo prelevare stramite svn dall seguente indirizzo svn://anonsvn.kde.org/home/kde/branches/KDE/3.5/kde-common/admin;
Rilanciamo il comando build da kdevelop3 ed il gioco è fatto.

Scarica la bozza alla pagina
http://www.gnuton.org/blog/docs/realizzare-un-repository-debian/
Questa bozza contiene le mie prime esperienze sulla pacchetizzazione debian.