email – What is the difference between ports 465 and 587? – Stack Overflow

Ports 465 and 587 are intended for email client to email server communication (sending email).

Port 465 is for smtps – SSL encryption is started automatically before any SMTP level communication.

Port 587 is for msa – it is almost like standard SMTP port. SSL encryption may be started by STARTTLS command at SMTP level if server supports it and your ISP does not modify/filter server’s EHLO reply (reported 2014 Nov).

MSA should accept email after authentication (e.g. after SMTP AUTH). It helps to stop outgoing spam when netmasters of DUL ranges can block outgoing connections to SMTP port.

via email – What is the difference between ports 465 and 587? – Stack Overflow.

VNC on Slitaz

Symlink to SliTaz fonts and rgb.txt
Open terminal,su, Password: root
mkdir -p /usr/X11R6/lib/X11/fonts
ln -s /usr/share/fonts/X11/misc /usr/X11R6/lib/X11/fonts
ln -s /usr/share/X11/rgb.txt /usr/X11R6/lib/X11

As regular user start vnc server
vncserver
Enter password required for client connection.
tux@slitaz:~$ vncserver
xauth: /home/tux/.Xauthority not writable, changes will be ignored
xauth: error in locking authority file /home/tux/.Xauthority
Couldn’t start Xvnc; trying default font path.
Please set correct fontPath in the vncserver script.

New ‘X’ desktop is slitaz:1

Starting applications specified in /home/tux/.vnc/xstartup
Log file is /home/tux/.vnc/slitaz:1.log

Verify vncserver is running:
tux@slitaz:~$ pgrep -l Xvnc
879 Xvnc
vncserver is working regardless of error messages

As regular user stop vnc server:
vncserver -kill slitaz:1

Configure xstartup
leafpad /home/tux/.vnc/xstartup

#!/bin/sh
openbox-session &
pcmanfm -d &

sumber : http://forum.slitaz.org/topic/problems-with-tightvnc

public_html

In order to enable the user-specific public_html directory open up a terminal and switch to the apache module config directory:

cd /etc/apache2/mods-enabled

If you list all the files inside this directory you’ll notice that all of them are actually symbolic links. To enable mod_userdir, which is the module you’re interested in, you’ll have to create two symlinks to the relevant files:

sudo ln -s ../mods-available/userdir.load

sudo ln -s ../mods-available/userdir.conf

All done! Now restart Apache via:

sudo apache2ctl restart

We can now access the web applications stored in our /home/username/public_html directory via http://localhost/~username/

source : http://heriman.wordpress.com/2008/08/05/enabling-apache-user-home-public_html-directory-in-ubuntu

Menginstall JDK pada Ubuntu secara manual

Untuk menginstall JavaSE JDK di Ubuntu, terlebih dahulu download jdk yang diinginkan di http://www.oracle.com/technetwork/java/javase/downloads/index.html. Pilih file bin untuk di install di Ubuntu. Setelah filenya selesai didownload rubah file permisionnya dengan

sudo chmod a+x [FILE_JDK].bin

Copy file tersebut folder yang inginkan, semisal ke /usr/lib/local/, kemudian jalankan dengan perintah

./[FILE_JDK].bin

yang akan menghasilkan folder instalasi jdk yang akan kita sebut dengan [JAVA_HOME]. Supaya dapat dikenali Ubuntu sebagai suatu library, perlu dibuat link ke [JAVA_HOME]/bin/java dengan perintah

sudo update-alternatives --install "/usr/bin/java" "java" "/usr/lib/local/[JAVA_HOME]/bin/java" 0
sudo update-alternatives --set "/usr/bin/java" "/usr/lib/local/[JAVA_HOME]/bin/java"

dan jangan lupa untuk menambahkan

JAVA_HOME=/usr/lib/local/[JAVA_HOME]
export JAVA_HOME
PATH=$PATH:$JAVA_HOME/bin
export PATH

di file .bashrc pada /home/[USER]/

Understanding file permissions and modifying them using chmod

Now that you have learnt what file permissions are, the next obvious part is to learn how to modify them. You have to use the chmod command to change the permissions of a file or directory. To run chmod on a file you should either own the file or you should be the superuser .

The way to use chmod is

$ chmod [newpermissions] [filenames]

Now comes a bit tricky part for beginners (more so for those who don’t have a mathematical background), but I shall try to explain the problem. For chmod the newpermissions have to set using an octal number rather than a decimal number. In case you understood the previous sentence, then you have no problems. If you didn’t then read the next paragraph.

Note : In case you don’t want to understand the octal system method there is a simpler method stated at the end of this article. But the octal number method is almost used by all (atleast by those who consider themselves to be powerusers)

I will not explain the concepts behind octal numbers. I shall only talk about the octal numbers that could be used with chmod. Below are the octal numbers representing different permissions

r, w, x Permissions
Binary
Octal

000
0
–x
001
1
-w-
010
2
-wx
011
3
r–
100
4
r-x
101
5
rw-
110
6
rwx
111
7

You have learnt that there are 9 bits associated with every file / directory (split into 3 parts) to decide the permissions. So in case you have the r,w,x permissions set for a file translate that to a 111 which you should further translate to the number 7 using the above table.

Suppose there is a file with the following permissions as shown in this sample ‘ ls ‘ output

frwxr-xr-x 4 david david 1240 Jan 15 08:12 viewresume


The existing permissions for the above file in octal numbers could be represented as follows

rwxr-xr-x
==> 111101101 ==> 755

That’s it!! I guess it wasn’t so tough after all. Use the above table and figure out the permissions for other files as well. Once you get used to these conversions, you would be able to do it in no time.

Now in case you want to change the permissions so that group members and others can neither read nor execute this file, you would require the new permissions to look something like the following

rwx—— ==> 111000000 ==> 700

So the exact command that you would be typing at the prompt would be

$ chmod 700 viewresume

Now check the permissions of the file once again with an ‘ ls ‘ command and you would see the changes that you just made.

For your quick reference here are a few standard numeric codes (that’s what it is called) that are often used..

Frequently used numeric parameters for chmod
755
The general preferred permissions for almost all the files on your disk
700
Extremely private data
500
Extremely private data that you would not like to accidentally modify. So write protect it
775
General files used when working as a Group (Others can only view/execute your files)
770
Important files used when working as a Group (Others cannot do anything with your files)
750
Allowing group to view your files but no write access (Others cannot do anything with your files)
777
Something you should never want to do 😉


There’s another method to change the permissions of files rather than using these octal numbers (in case you just didn’t get the hang of it). I prefer the octal number method. Others may prefer the following method

$ chmod g-r,g-x,o-r,o-x viewresume

The above command does exactly the same thing that ‘ chmod 700 ‘ command did. Yeah this one is lengthier but its simpler to understand. Its explained below in case you couldn’t figure it..

g-r g = group – (hyphen) = remove r = read permission
o-x o = other(world) – (hyphen) = remove x = execute permission


I guess you got the point.. the other 2 parameters (g-x,o-r) can also be expanded in the same way. Thus the above command asks Linux to remove the r and x permission for both the group members and others (rest of world).

Here is a quick reference if you prefer to use this method (its called the symbolic method)

Symbolic parameters for chmod
u
User (yourself)
g
Group (members of the same group)
o

Others (rest of world)

a
All of the above 3 (u,g and o)

Remove this permission

+

Add this permission

=

Set to this permission

r

Read access

w
Write access
x
Execute access.


Here is another example to make things more clear.

$ chmod g=rwx myprogram.c

The above command would give the group that the file belongs to, read-write-execute permissions irrespective of what the previous permissions were (for the file named myprogram.c)

I have discussed how to use chmod with parameters in numeric mode(755,700, etc.) in more detail than using it with parameters in the symbolic mode (u,g,o, etc.). This is because I have never used the symbolic mode of chmod. I had to refer to my books to get the technical details for this article. I have been using the octal numeric mode since the first time I used chmod.

 

Source : http://www.codecoffee.com/tipsforlinux/articles/032-2.html