The /etc/passwd file in Linux is a file that contains a list of users, and information about those users. We can use this file to list all users that exist in our system. For example, using the “cat” command will output the whole file. Notice that every line starts with the username field.
oot@bt:~# cat /etc/passwd root:x:0:0:root:/root:/bin/bash daemon:x:1:1:daemon:/usr/sbin:/bin/sh bin:x:2:2:bin:/bin:/bin/sh sys:x:3:3:sys:/dev:/bin/sh sync:x:4:65534:sync:/bin:/bin/sync games:x:5:60:games:/usr/games:/bin/sh man:x:6:12:man:/var/cache/man:/bin/sh lp:x:7:7:lp:/var/spool/lpd:/bin/sh mail:x:8:8:mail:/var/mail:/bin/sh news:x:9:9:news:/var/spool/news:/bin/sh uucp:x:10:10:uucp:/var/spool/uucp:/bin/sh proxy:x:13:13:proxy:/bin:/bin/sh www-data:x:33:33:www-data:/var/www:/bin/sh backup:x:34:34:backup:/var/backups:/bin/sh list:x:38:38:Mailing List Manager:/var/list:/bin/sh irc:x:39:39:ircd:/var/run/ircd:/bin/sh gnats:x:41:41:Gnats Bug-Reporting System (admin):/var/lib/gnats:/bin/sh libuuid:x:100:101::/var/lib/libuuid:/bin/sh syslog:x:101:103::/home/syslog:/bin/false sshd:x:102:65534::/var/run/sshd:/usr/sbin/nologin landscape:x:103:108::/var/lib/landscape:/bin/false messagebus:x:104:112::/var/run/dbus:/bin/false nobody:x:65534:65534:nobody:/nonexistent:/bin/sh mysql:x:105:113::/var/lib/mysql:/bin/false avahi:x:106:114::/var/run/avahi-daemon:/bin/false snort:x:107:115:Snort IDS:/var/log/snort:/bin/false statd:x:108:65534::/var/lib/nfs:/bin/false usbmux:x:109:46::/home/usbmux:/bin/false pulse:x:110:116::/var/run/pulse:/bin/false rtkit:x:111:117::/proc:/bin/false festival:x:112:29::/home/festival:/bin/false postgres:x:1000:1000::/home/postgres:/bin/sh
Now, if we want to refine our search and filter out all that extra information and just print the usernames, we can use the “awk” command like this:
awk -F ':' '{print $1}' /etc/passwdIn this command the “-F” option tells awk the separating field, in this case the colon “:”, and the {print $1} option, is just to print out the first field, which is the username field.
root@bt:~# awk -F ':' '{print $1}' /etc/passwd
root
daemon
bin
sys
sync
games
man
lp
mail
news
uucp
proxy
www-data
backup
list
irc
gnats
libuuid
syslog
sshd
landscape
messagebus
nobody
mysql
avahi
snort
statd
usbmux
pulse
rtkit
festival
postgres
I decided to make a guide about TCP/IP configuration in Linux, and you may ask: well, what Linux distribution in specific? I know!, there are hundreds of Linux distribution, but for this guide, I’m only going to cover the two most used Linux distribution: Ubuntu and Fedora. Ubuntu is a Debian derivative, so the Ubuntu portion of TCP/IP configuration applies to any distro based on Debian. And the same goes for Fedora, which is based on RedHat Linux.
First, you want to find out what interfaces you have, and what ip address, “if any,” was assigned to your computer. For this use the “ifconfig” command:
ifconfig #will list all enabled interfaces
if you are looking for a specific interface:
ifconfig eth0 #will only display the configuration for eth0 interface
If you get no interfaces other than the loopback address, it is time to do some troubleshooting and find out whether your network card was detected by Linux or not.
sudo lspci | grep -i ethernet #displaying all your ethernet cards
if you’re troubleshooting a wireless card just change “ethernet” for “wireless.”
other useful command when troubleshooting network card and drivers is “lsmod” Read the rest of this entry »
After having to reset my Ubuntu box password, I decided to come up with this tutorial on how to reset linux password, in this case we will be taking two different methods…
An SSH tunnel (sometimes referred to as a VPN) is an encrypted network tunnel created through an SSH connection. SSH is frequently used to tunnel insecure traffic over the Internet in a secure way. For example, if you were to check your webmail over the internet your username and password would be send in clear text format, meaning that anyone with a sniffer and using ARP poisoning techniques could intercept your credentials. To browse the internet securely, one can establish an SSH tunnel that routes all HTTP traffic to the ssh server inside an SSH-encrypted connection. Even though the HTTP traffic itself is insecure, because it travels within an encrypted connection it becomes secure.
In order to create an SSH tunnel, the SSH client is configured to forward a specified remote port and IP address (that is accessible on the SSH server) to a port on the local machine. Once the SSH connection has been established, the user can connect to the specified local port to access the network services that would otherwise be available only at the remote IP address and port. For this tutorial I would be setting up SSH server in Ubuntu, and the client pc a windows xp using Internet Explorer as the browser, I know… not the best OS and browser, but I think that’s what most people use.
In todays hybrid network where Windows and Linux coexist together, I found myself trying to access remote shares from a Linux box and vise versa, having to input credentials to authenticate, well this little tutorial shows a quick and easy way to mount windows network shares in PCLinux with read/write permission, keep in mind that prior to mount the share a user should exist on the remote system in order to authenticate, also notice that the credentials are kept in a clear text file on the Linux box and will be sent during authentication, as it poses a security threat.
click here to view the tutorial
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