Wednesday, December 14, 2016

Blockstack Guide

https://blockstack.org/articles/browser-beta
:https://github.com/blockstack/blockstack-cli
:pip install --upgrade setuptools pip
:apt-get install libffi-dev
brew install libffi openssl
virtualenv -p /usr/bin/python2.7 blockstack-cli-venv
source blockstack-cli-venv/bin/activate
pip install --upgrade pip
pip install --upgrade blockstack

$ sudo pip install virtualenv
$ virtualenv /tmp/blockstack-install
$ cd /tmp/blockstack-install
$ source bin/activate
(blockstack-install) $ pip install blockstack

Friday, September 16, 2016

Summary of my SMSbots

mm-1.4.2.tar.gz

sudo make clean
sudo chmod +x *.*


sudo apt-get install virtualbox-guest-utils virtualbox-guest-x11 virtualbox-guest-dkms
sudo reboot
sudo apt-get install virtualbox-guest-utils virtualbox-guest-x11 virtualbox-guest-dkms
sudo reboot
sudo apt-get install build-essential manpages-dev
nano /etc/hosts
sudo nano /etc/hosts
sudo nano /etc/hostname
sudo apt-get update
sudo apt-get install gcc
sudo apt-get install build-essential
sudo reboot now
ls
cd Downloads/
ls
cd smstools3/
ls
cd scripts/
ls
cat README
cd ..
sudo ./install.sh
sudo make -s install
nano /etc/smsd.conf
ls
cd ..
ls
cd mm-1.4.2/
ls
sudo ./configure
ls
sudo make
sudo make install
cd ~
sudo tail -f /var/log/syslog
sudo apt-get install usb-modeswitch gsm-utils
sudo apt-get install usb-modeswitch gsm-utils --fix-missing
sudo apt-get install usb-modeswitch
lsusb
ls
cd Downloads/
ls
cd usb-modeswitch-2.3.0/
ls
sudo make
sudo make install
sudo tail -f /var/log/syslog
sudo apt-get install usb-modeswitch gsm-utils
sudo tail -f /var/log/syslog
sudo reboot now
gksu nautilus
sudo tail -f /var/log/syslog
lsusb
sudo apt-get install usb-modeswitch gsm-utils
sudo tail -f /var/log/syslog
cd /sys/class/tty/
readlink ttyUSBn
cd /sys/devices
find -name "ttyUSB0"
cd ~
lsdev
sudo apt-get install procinfo
lsdev
ls -l /dev/tty*
dmesg
sudo echo "SMS Test Message" | gsmsendsms -d /dev/ttyUSB0 -b 19200 +601120209999
sudo echo "SMS Test Message" | gsmsendsms -d /dev/ttyUSB1 -b 19200 +601120209999
sudo echo "SMS Test Message" | gsmsendsms -d /dev/ttyUSB3 -b 19200 +601120209999
udevadm info -a -p /sys/bus/usb-serial/devices/ttyUSB0/
screen /dev/ttyUSB0
sudo apt-get install screen
screen /dev/ttyUSB0
screen /dev/ttyUSB1
screen /dev/ttyUSB2
ls -l /dev/ttyUSB0
ls -l /dev/ttyUSB1
ls -l /dev/ttyUSB2
ls -l /dev/ttyUSB3
ls -l /dev/ttyUSB4
ls -l /dev/ttyUSB5
ls -l /dev/ttyUSB01
dmseg
dmsg
dmesg
ls -l /dev/
pppd call huaweiparam
ls -l /dev/ttyUSB*
sudo ls -l /dev/ttyUSB*
sudo su
udevadm info --query all -name /dev/ttyUSB0 --attribute-walk
sudo udevadm info --query all -name /dev/ttyUSB0 --attribute-walk
ls -l /sys/bus/usb-serial/devices
sudo ls -l /sys/bus/usb-serial/devices
/usr/local/bin/smsd -s
sudo /etc/init.d/sms3 start
sudo /usr/local/bin/smsd -s
sendsms 601120209999 'Hello, how are you'
sudo sendsms 601120209999 'Hello, how are you'
cat /var/spool/sms/outgoing
sudo cat /var/spool/sms/outgoing
cd /var/spool/sms/outgoing
sudo cd /var/spool/sms/outgoing
cd /var/spool/sms/
sudo su
sudo /etc/init.d/sms3 stop
wget ftp://ftp.ossp.org/pkg/lib/mm/mm-1.4.2.tar.gz
ls
cd Downloads/
ls
cd mm-1.4.2/
ls
sudo make install
cd /usr/local/bin/smsd -s
sudo /usr/local/bin/smsd -s
sudo cat /var/log/smsd.log
cd /usr/local/src
ls
cd mm-1.4.2/
ls
sudo ./configure
sudo make
sudo make install
sudo nano /etc/ld.so.conf
cd ~
ls
cd Downloads/
ls
cd smstools3/
ls
sudo /etc/init.d/sms3 start
sudo /etc/init.d/sms3 stop
sudo /usr/local/bin/smsd -s
sudo nano /etc/ld.so.conf
sudo /usr/local/bin/smsd -s
sudo nano /etc/ld.so.conf
ldconfig
sudo ldconfig
sudo /usr/local/bin/smsd -s
sudo nano /etc/ld.so.conf
sudo ldconfig
sudo /usr/local/bin/smsd -s
sudo nano /etc/ld.so.conf
sudo ldconfig
whereis smsd.conf.full,
whereis smsd.conf.full
cat /etc/smsd.conf
lsdev
lsusb
sudo tail -f -n1 /var/log/smsd.status
sudo apt-get install gnome-system-tools
lsusb
lsdev
dmesg
sudo /etc/init.d/sms3 start
sudo sendsms 601120209999 'Hello, how are you'
sudo tail -f -n1 /var/log/smsd.status
sudo cat /var/log/smsd.log
dmesg | grep ttyS
dmesg | grep tty
dmesg | grep usb
ls -l /dev/ttyUSB*
dmesg
lsusb
sudo modprobe usbserial vendor=0x12d1 product=0x14db
dmesg
ls -l /dev/ttyUSB*
sudo ls -l /dev/ttyUSB*
sync
reboot now
sudo reboot now
dmesg
sudo usbserial vendor=0x12d1 product=0x14db
usbserial vendor=0x12d1 product=0x14db
sudo modprobe usbserial vendor=0x12d1 product=0x14db
dmesg
lsusb
lsdev
sudo ls -l /dev/ttyUSB*
sudo ls -l /dev/tty*
cd /etc/modules
sudo nano /etc/modules
sudo reboot now
gksu nautilus
sudo ls -l /dev/tty*
lsdev
sudo ls -l /dev/ttyUSB*
dmesg
sudo /etc/init.d/sms3 start
sudo sendsms 601120209999 'Hello, how are you'
sudo tail -f -n1 /var/log/smsd.status
sudo cat /var/log/smsd.log
sudo nano /etc/smsd.conf
sudo /etc/init.d/sms3 stop
sudo nano /etc/smsd.conf
sudo /etc/init.d/sms3 start
sudo sendsms 601120209999 'Hello, how are you'
sudo cat /var/log/smsd.log
sudo /etc/init.d/sms3 stop
dmesg
sudo /etc/init.d/sms3 start
sudo sendsms 601120209999 'Hello, how are you'
sudo cat /var/log/smsd.log
sudo /etc/init.d/sms3 stop
lsusb
dmesg

gksu nautilus


# Example smsd.conf. Read the manual for a description

devices = GSM1
logfile = /var/log/smsd.log
loglevel = 7

[GSM1]
device = /dev/ttyUSB0
incoming = yes
pin = 0123
baudrate = 19200

Saturday, April 23, 2016

Summary of my Telebots

echo -ne "\033[9;0]" >> /etc/issue
sudo vi /etc/apt/sources.list
sudo nano /etc/ssh/sshd_config
sudo nano /etc/ssh/ssh_config
sudo service ssh restart
sudo reload ssh
sudo apt-get install openssh-server

sudo apt-get install git
sudo git clone addressurl
sudo apt-get install python3-pip
python3 --version
pip3 install python-telegram-bot
pip3 install future
python3 -c "import telegram;print(telegram.__version__)"

sudo ssh-keygen -t rsa
sudo ssh-copy-id username@server
sudo rsync -a bot.sqlite -e "ssh -p 1234" username@server:/home/admin/Backup
echo "1234" | sudo -S rsync -a /home/username/python-telegram/bot.sqlite -e "ssh -p 1234" username@server:/home/username/Backup/??/bot-1m.sqlite


https://pypi.python.org/pypi/python-telegram-bot/1.4
https://pypi.python.org/pypi/python-telegram-bot#downloads
Newbie Guide - https://python-telegram-bot.org/
TempSend - http://tempsend.com/

Friday, April 22, 2016

rsync Tips

sudo rsync -a bot.sqlite -e "ssh -p 1234" admin@server:/home/admin/Backup

Tuesday, April 12, 2016

Python Version

Python2 is the default Python version in Ubuntu. To change to python3, you can use the following command:

alias python=python3

This will change the default version to Python3.

To revert back:

alias python=python2

Saturday, April 9, 2016

How to setup crontab ubuntu server terminal without sudo?

I won't get into how much this is a bad idea; simply put, running sudoin crontab requires your password to be stored somewhere in plaintext.
It's a bad idea.

The following is the preferred method of running administrative tasks through cron. Since you don't really need to write sudo in the crontab, if you are modifying root's crontab.

Use root's crontab

Run the following command:
sudo crontab -e
This opens up root's crontab. sudo is not necessary to run your command in this context, since it'll be invoked as root anyway.
Therefore, you would simply append the following to root's crontab.
@hourly rm somefile

Now, if you absolutely want to be unsafe and take risks with your password, the following will run your command from your own crontab, and enter your password automatically when prompted by sudo.
Again, this is not recommended.

In your own crontab, write your command like so:
@hourly echo "password" | sudo -S rm somefile
The obvious disadvantage here is that, should anyone ever access your crontab, your password will be readable in plaintext.
You shouldn't do this.
shareimprove this answer
   
I got it, thanks a lot – sayem siam Aug 9 '12 at 18:11
1 
Glad it works! Just be wary of any security holes you leave behind.. They might come back later to haunt you. – SirCharlo Aug 9 '12 at 18:15
1 
@SirCharlo Why use root's user crontab instead of the systemwide crontab /etc/crontab? – Eliah Kagan Aug 10 '12 at 3:47
1 
@Elijah why not? – SirCharlo Aug 11 '12 at 4:43
If you are putting the script from one of the cron directories (/etc/cron.*) then you don't need to use sudo as that is running as root.
If you are using crontab, then you will want to use root's crontab. This will run it as root, and also not need sudo.
sudo crontab -e
shareimprove this answer
   
I would also place the command in /etc/cron.hourly/something. That's what these directories are for. – John S Gruber Aug 23 '12 at 15:37
2 
No. You could put it in /etc/cron.SOMETHING/SCRIPT, but I wouldn't do both. Both would give roughly the same function, although using crontab you would have a bit more power over how often/when things run. – tgm4883 Aug 23 '12 at 17:40
   
I should have made clear that I meant that as an alternative. Thanks. – John S Gruber Aug 23 '12 at 17:43

Run following command in terminal
sudo visudo
Added the following line to the end of the file:
vidyadhar  ALL= NOPASSWD: /bin/rm
In the above example vidyadhar is the username and it will not ask for password if you are running rm command through vidyadhar.

How to disable blank screensaver on Ubuntu Server?

Prevent screen from turning off

You can run this command:
$ setterm -blank 0 -powerdown 0
Alternatively you can disable console blanking permanently using the following command:
# echo -ne "\033[9;0]" >> /etc/issue


Type setterm -blank 0 on any shell to disable blanking out of tty consoles.
Type sudo xset s 0 0
0 disables blanking, any value greater than 0 is the time in minutes. Default is 10.
To permanently enable this you can add this line to your ~/.bashrc config.

Friday, April 1, 2016

How to load a USB device to Ubuntu and recognize as /dev/ttyUSB*



Serial Port Setup

You need to be a member of the group that owns the serial port device connected to your rig. On Debian-based systems such as Debian GNU/Linux, Ubuntu and its derivatives (Kubuntu, Xubuntu, Lubuntu etc.) and Mint, just to name a few, this is the "dialout" group. On other systems you can determine the group you need to join with this command:
$ ls -l /dev/ttyUSB*
(If this doesn't return any files, use "ls -l /dev/ttyS*" instead.)
This should give you a list of one or more serial port devices of the form:
crw-rw---- 1 root uucp 188, 0 Jul 22 02:49 /dev/ttyUSB0
In this case the serial device is owned by user "root" and group "uucp", so you want to add yourself to the "uucp" group. In the examples below we will use "dialout" for the group we need to join.
There are several ways to add yourself to a group.
From a terminal, you can enter the following command
$ sudo adduser (username) dialout
Substitute your login name for (username)
You can check to be sure that you are now a member of the dialout group with the command:
$ groups
which should respond with the full list of groups you belong to.
There are also Graphical User Interface tools that perform the same basic function. On Lubuntu this is the "users-admin" command which is usually found on the Lubuntu menu item "System Tools | Users and groups". You can of course start that tool from the command line
$ sudo users-admin
sudo is used for all of these modifications to ensure that you have the correct read/write privilege for the files that will be changed. You must log out and log back in again for the change to take effect.

Mint distribution

Contributed by Charlie, NA5NM
  • Goto "Menu" and select "Control Center."
  • In the "Control Center" select "Users and Groups."
  • Under "Users and Groups" you will select "Manage Groups"
  • A list of all the different groups will appear so you may scroll through the list to find 'dialout' select it then press the "Add" key.
  • You must log out and log back in again for the changes to take effect.

Ubuntu Unity desktop

Contributed by Dave, WB5NHL
  • Click on "Dash Home" symbol in upper left corner of the desktop
  • Key "users" click on the "Users and Groups" icon
  • Select "Manage Groups"
  • A list of all the different groups will appear so you may scroll through the list to find 'dialout'
  • Highlight "dialout" and select "Properties"
  • If the box next to your name is checked, you are a member of the dialout group. If not, check the box!
  • You must log out and log back in again for the changes to take effect.

Korora (based on Fedora)

Contributed by John, KC5LAA
· Go to “Menu” and select “Administration” > “Users and Groups”
· Under “Edit” select “Preferences” and uncheck “Hide system users and groups”, then exit “Administration”
· Select “Groups” tab
· A list of all the different groups will appear so you may scroll through the list to find “dialout”
· Highlight “dialout” and select “Properties”
· Select “Group Users” tab
· Scroll down through the list of users to find your name.
· Make sure the box next to your name is checked.
· Select “OK” to exit the “Properties” window.
· Exit “Users and Groups” window
You must log out and log back in again for the changes to take effect.

USB->RS232 adapters

The serial drivers may need to be installed for the device to work properly. After plugging in the device, first check the hardware messages to see the device was detected:
dmesg
Torward the end of the messages, you should see this:
usb 1-1: new full speed USB device using uhci_and address 2
usb 1-1: configuration #1 chosen from 1 choice
Now, we need to figure out the device vendor number and product number to tell the usbserial driver. For this we can use lsusb. The easiest way to find the information is to first unplug the device, then run lsusb:
lsusb
You will see a summary list of your USB devices on the system, for example:
Bus 001 Device 001: ID 0000:0000
Now, plug the device back in, and run lsusb again:
lsusb
Which returns the summary list again, but now showing the new USB device:
Bus 001 Device 002: ID 4348:5523
Bus 001 Device 001: ID 0000:0000
Now, we can load up the driver for this device:
sudo modprobe usbserial vendor=0x4348 product=0x5523
Finally, check dmesg again to ensure it loaded properly.
dmesg
Near the end, you should see something like:
usbserial_generic 1-1:1.0: generic converter detected
usb 1-1: generic converter now attached to ttyUSB0
usbcore: registered new interface driver usbserial_generic
Congratulations, your link is up - in this example, the device can be used on /dev/ttyUSB0. As much fun as you had doing this, there is some chance you want to do this automatically in the future. Just add this line:
usbserial vendor=0x4348 product=0x5523
to /etc/modules with the vendor and product numbers you found. Of course you must user sudo to edit that file.

Virtualbox Ubuntu Screen Resolution Fix

sudo apt-get install virtualbox-guest-utils virtualbox-guest-x11 virtualbox-guest-dkms

Blast SMS


  • https://www.diafaan.com/reviews/use-diafaan-sms-server-with-android-phones/
  • http://b.fl7.de/2014/05/huawei-e303-sms-vulnerability-CVE-2014-2946.html
  • https://hashtips.wordpress.com/2013/04/12/send-sms-using-a-usb-modem-and-ubuntu-12-04/
  • http://www.techytalk.info/send-receive-sms-using-gsm-modem-phone-ubuntu/
  • http://www.draisberghof.de/usb_modeswitch/
  • http://stefanfrings.de/smstools/SMS_Applications.pdf (important)

:sudo apt-get install gnome-system-tools

Thursday, March 31, 2016

SMS Blast Tool

#. smscaster
#. http://smstools3.kekekasvi.com/
#. http://www.kannel.org/

Tuesday, March 22, 2016

Saturday, March 19, 2016

Blasting Apps


  • http://www.smsblastr.com/#prettyPhoto
  • https://www.youtube.com/watch?v=iom9WoF9I7E

How to set up USB for Virtualbox?

USB in different versions of Virtual Box

For use of USB in Virtual Box 3.x you need a PUEL-version. From Virtual Box > 4.x USB 1.0 is supported in the OSE version installed from software center. For USB 2.0 or USB 3.0 (from Virtual Box > 5.x) we need to install an extension pack free for download from Oracle. This will make our Virtual Box a PUEL-Version (see this question on details on how to install Virtual Box from the Oracle repository).
To change settings of a virtual machine needs the guest to be powered off.

Become a "vboxuser"

To be able to get access to an attached USB device the Ubuntu host user needs to be in the vboxusers group. This can be done from Users and Groups after having installed the gnome-system-tools Install gnome-system-tools or from the command line by
sudo usermod -aG vboxusers <username> 
We need a reboot or logout/login for group membership to take effect. On a Windows host a special kernel module will provide USB access.

Activate USB support in Virtual Box Manager

We need to activate the virtual USB driver in our guest OS.
Note that we can only change these settings when the virtual machine is in shut down state.
In the USB settings from Virtual Box Manager tick "Enable USB Controller" For enabling the USB 2.0 driver also tick "Enable USB 2.0 (EHCI) Controller".
enter image description here

Select host USB device for access from the guest

To grant access to USB devices we need to select a device to disable in the host and to enable in the guest (this is a precaution to avoid simultaneous access from host and guest). This can be done from the panel Devices menu or by right mouse click in the bottom panel of the Virtual Box Manager on the USB icon:
enter image description here
Tick the device you need in the guest, untick it if you need it in the host. The selected device will immediately be accessible from the guest. A Windows guest may need additional drivers:
enter image description here
Windows 10 may not accept an NTFS formatted USB pen drive.

Use USB filters for permanent access in the guest

By defining USB filters we can define USB devices that will automatically be presented to the guest when booting the guest OS.
enter image description here
Click on the green + symbol on the right to add a known device.
Note, that some devices may lead to a boot failure of the guest. We can not use these devices for filters.
Read more on USB support in the Virtual Box User Manual.

Saturday, March 12, 2016

How to fix infinite loop in WinXP activation?

Let's keep it quick and short


Safe Mode with Command Prompt
:explorer.exe
rundll32.exe syssetup,SetupOobeBnk
:regedit
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\WPAEvents
OOBETimer: FF D5 71 D6 8B 6A 8D 6F D5 33 93 FD
WPAEvents | Permissions | SYSTEM | Deny Full Control
:%systemroot%\system32\oobe\msoobe.exe /a
Activate on the Phone | Change Product Key: THMPV 77D6F 94376 8HGKG VRDRQ
:%system
https://www.youtube.com/watch?v=_ntK8a-dBo0

Thursday, March 3, 2016

How to compile Hirocoin from source code?

UNIX BUILD NOTES
====================

To Build
---------------------

cd src/
make -f makefile.unix # Headless hirocoin
sudo apt-get install libminiupnpc-dev
sudo apt-get install libdb++-dev
sudo apt-get install python-zope.interface python-twisted python-twisted-web


/ip firewall nat
add action=dst-nat chain=dstnat dst-port=9347 in-interface=maxis-airkayu protocol=tcp to-addresses=192.168.3.37 to-ports=9347 disable=​no​ comment="HIROCOIN"

/ip firewall mangle
add action=mark-connection chain=prerouting comment="HIROCOIN" new-connection-mark=WAN2_mark passthrough=no src-address=192.168.​3.37​

Tuesday, February 23, 2016

Mikrotik UNIFI initial setup guide



Interfaces

Name: ether1-gateway
MTU: 1500
L2 MTU: 1598
ARP: Enabled
VLAN
VLAN ID: 500
Name: vlan500
MTU: mtu1500
VLAN
VLAN ID: 600
Name: vlan600
MTU: mtu1500


PPP

Name: unifi
Type: PPPoE Client
Max MTU: 1492
Max MRU: 1492
Interfaces: vlan500
User: yourusername@unifi
Password: yourunifipassword


Bridge

Name: bridge-iptv
Type: Bridge
MTU: 1500
Name: bridge-local
Type: Bridge
MTU: 1500

Monday, February 22, 2016

Execute sudo command without authenticating via password

The approach to solve your problem is to put your user in sudoers file, like you can see.
Open terminal window and type:
sudo visudo
In the bottom of the file, type the follow:
username ALL=(ALL) NOPASSWD: ALL
Where username is your username in your system. Save and close sudoers file (if you haven't changed your default terminal editor (you'll know if you have), press ctl+x to exit nano (but note that the screenshot below shows vim), and it'll prompt you to save).
sudoers file]
After this, you can, in terminal window, type sudo <Whatever you want>, without being prompted for the password.
This only applies, to sudo command in terminal window. For example, when you try to install a package in software center, you will be prompted to insert your password, like you can see in the next Screenshot.

Sources: http://askubuntu.com/questions/147241/execute-sudo-without-password

Friday, February 19, 2016

My favorite Telegram Bots

My objective is to create my own bot @EscrowBot. Found plenty of Telegram Bots out there, trust me! But, I prefer to list down my all time favorite bots here for future development and providing you an easy guide to set up - forget it. Plug and play, everything handled by API. All these bots are written in Phyton, Java, C#, Ruby, Go, Lua and Haskell. I have only experienced Phyton and Lua myself

https://github.com/yagop/telegram-bot (written in LUA)
https://github.com/jh0ker/welcomebot (written in PYTHON)
https://github.com/yukuku/telebot  (written in PYTHON)

Bots Library of Python
https://github.com/python-telegram-bot

@BotFather is compulsory to hook them up with API


Yagop and Yukuku, both already have a well written guide. So, I will not emphasize anymore as it is straight out of box. But, I would like to thank Jannes Hoke, @jh0ker creator of welcomebot who gave me on site support over my deployment. I really appreciate that 5 hours sessions because I couldn't find any guide out there to help me out. Hence, I decided to write a guide to help the community before I have memory loss.

Note that Python has many libraries. Ensure that you feed the bots with the correct Python library and host them correctly. For telebot and welcomebot, you may simply host it at Ubuntu 14.04 desktop whereas telegram-bot, you may host it at Google Appspot Cloud Console. Environment is different, even though I try to host welcomebot there, it throws out a bunch of errors. So, don't use it! Lead developer agreed with me.

Now, you got to look at the PYTHON itself, welcomebot uses python3. In fact, both version of python2 and python3 can coexist in Ubuntu 14.04, just make sure you load the library in the correct environment so that the examples of clibot.py, echobot2.py located in python-telegram-bot-master may test run flawlessly before you put actual test on welcomebot.

Some terminal commands you may need below
Brought to you by www.airkayu.com

sudo apt-get install python-pip
sudo python clibot.py
sudo python echobot2.py
pip3 install python-telegram-bot
sudo apt-get install python3-pip
python3 --version
Optional: sudo pip3 install -r requirements.txt
python3 -V
Optional: sudo pip3 install -r requirements-dev.txt
Optional: sudo make test
sudo python3 bot.py 

Don't forget reboot!

Tuesday, February 16, 2016

How to create startup terminal auto-launch for Ubuntu

Alright, you will need make a startup, add program and insert the command below:-
sh -c "sh /home/administrator/Documents/masternode.sh"

Next, you will need a sample script "masternode.sh" and have the following shell script below and Hurray! There, you are good to go. Cheers!
#!bin/sh

sleep 15
gnome-terminal --geometry=75x45 --title=Masternode --execute bash -c "sleep 5; cd ~; sudo ./dashd; sleep 60; sudo ./dashd getinfo ;bash"

#gnome-terminal -e "cd ~ && sudo ./dashd"
 
Brought to you by www.airkayu.com