Category: Linux

xrdp
xrdp allow you to connect to Linux Desktop using Windows Remote Desktop.

First you need to install desktop environment. Installing something light weight like XFCE is better if you are using a remote server.
```
apt-get install xfce4
```
This will download approx 500 MB of files and install on Ubuntu 16.04.

Next install xrdp
```
apt-get install xrdp
```
You need to open port 3389 in firewall.

Some of the configuration files are
```
/etc/default/xrdp
/etc/xrdp/startwm.sh
/etc/xrdp/xrdp.ini
```
March 26, 2018
useradd
To create a user, run
```
useradd -m -s /bin/bash USERNAME
```
-m = create home directory.
-s = specify location of shell.

To create a user with custom home directory, use
```
useradd -d /var/www -s /bin/bash USERNAME
```
Create User with Specific User id

Create the user “serverok” with uid 4223, run
```
useradd -u 4223 serverok
```
Create User to Run System Service

-r option select gid/uid for running system service.
```
groupadd -r prometheus
useradd -r -g prometheus -s /sbin/nologin -d /usr/hostonnet/prometheus/ -c "prometheus Daemons" prometheus
```
Related commands

Create, delete, and modify local user accounts
```
Add: useradd
Delete: userdel
Modify: usermod
```
Create, delete and modify local groups and group memberships
```
Add: groupadd
Delete: groupdel
Modify: groupmod
```
To add a user to sudo/wheel group, see usermod
March 24, 2018

rpaf

mod_rpaf is an apache module that translate proxy IP to real IP when apache web server is behind a proxy server.

To install on Ubuntu, run

apt install -y libapache2-mod-rpaf

Config file available at

root@vps528168:~# cat /etc/apache2/mods-enabled/rpaf.conf
    RPAFenable On

    # When enabled, take the incoming X-Host header and
    # update the virtualhost settings accordingly:
    RPAFsethostname On

    # Define which IP's are your frontend proxies that sends
    # the correct X-Forwarded-For headers:
    RPAFproxy_ips 127.0.0.1 ::1 193.70.86.5

    # Change the header name to parse from the default
    # X-Forwarded-For to something of your choice:
    RPAFheader X-Real-IP
root@vps528168:~#

Apache

March 24, 2018

Install pureftpd on Ubuntu

To install pure-ftpd on Ubuntu, run

apt install pure-ftpd -y

Create a system user

useradd -d /var/www -s /bin/bash USERNAME
chown -R USERNAME:USERNAME /var/www
passwd USERNAME

Enable Unix Authentication

To allow system user to login using FTP, edit file

vi /etc/pure-ftpd/pure-ftpd.conf

Uncomment the line

UnixAuthentication           yes

echo 'yes' > /etc/pure-ftpd/conf/UnixAuthentication

On Ubuntu, after default install, you have following settins.

root@server:/etc/pure-ftpd/auth# ll
total 8
drwxr-xr-x 2 root root 4096 Jan 28 05:52 ./
drwxr-xr-x 5 root root 4096 Jan 28 06:20 ../
lrwxrwxrwx 1 root root   26 Feb  5  2018 65unix -> ../conf/UnixAuthentication
lrwxrwxrwx 1 root root   25 Feb  5  2018 70pam -> ../conf/PAMAuthentication
root@server:~# cat /etc/pure-ftpd/auth/65unix 
no
root@server:~# cat /etc/pure-ftpd/auth/70pam 
yes
root@server:~#

PAMAuthentication enabled. UnixAutehticiation disabled. This allow system users to login using PAM.

pureftpd

March 24, 2018

Pure-FTPd
To install Pureftpd on CentOS, run
```
yum install pure-ftpd
```
To start/stop, use
```
systemctl start pure-ftpd
systemctl stop pure-ftpd
```
To enable system users to login, edit /etc/pure-ftpd/pure-ftpd.conf, un comment the line UnixAuthentication yes.
March 20, 2018
Reinstall a package using apt
To reinstall a package, run
```
apt install --reinstall PKG_NAME
```
Example

dpkg apt
March 18, 2018
dpkg
To force delete a package, run
```
dpkg --purge --force-depends PKG_NAME
```
List all Installed packages
```
dpkg -l
```
List all files in a package
```
dpkg -L PKG_NAME
```
To find which package provides a file
```
dpkg -S /usr/bin/nmap
```
Apt
March 18, 2018
File Sharing

pydio

Pydio is open source share sharing application. Source code available in github https://github.com/pydio

https://pydio.com

https://www.linshare.org

Scripts

March 17, 2018
Installing Asterisk from Source
You can download latest source code from

https://downloads.asterisk.org/pub/telephony/asterisk/

To install latest 15.x version, run
```
cd /usr/local/src
wget https://downloads.asterisk.org/pub/telephony/asterisk/asterisk-15-current.tar.gz
tar xvf asterisk-15-current.tar.gz
cd asterisk-15.2.2
./configure
make && make install
```
You will need to install dependency.

Asterisk
March 16, 2018
Installing Asterisk on Ubuntu
Ubuntu repository provide Asterisk, to install, just run
```
apt install asterisk
```
On Ubuntu 16.04, it come with asterisk 13.1, while newer version is 15.2.

It is better to install from source if you want latest software.

Asterisk
March 16, 2018
Errors
Compile Errors
Bash Errors
PHP Errors
- Warning: Use of undefined constant OAUTH_REQENGINE_CURL
Python pip Errors
- error: invalid command ‘bdist_wheel’
- ModuleNotFoundError: No module named ‘MySQLdb’
configure: error: *** uuid support not found (this typically means the uuid development package is missing)
```
yum -y install libuuid-devel
```
configure: error: *** JSON support not found (this typically means the libjansson development package is missing)
```
apt-get install libjansson-dev
yum install -y jansson-devel
```
configure: *** Please install the ‘libxml2’ development package.
```
yum -y install libxml2-devel
```
/bin/sh: 1: pkg-config: not found
```
apt -y install pkg-config
```
March 15, 2018
tcpdump
tcpdump is a useful command to track traffic on your network.

To see all traffic between your PC and a remote server, run
```
tcpdump -i any host google.com
```
Here all traffic to google.com will be displayed.

To save the logs to a file, use
```
tcpdump -i any host google.com -w /tmp/test.pcap
```
Monitor taffic to all ports other than a specific port.
```
tcpdump -c 100 port not 3333
tcpdump -w /tmp/test.pcap -c 100 port not ssh
```
To view all communications on a specific port, for example port 993. use
```
tcpdump  -i eth0 port 993
```
March 15, 2018

Category: Linux

Create User with Specific User id

Create User to Run System Service

Related commands

Enable Unix Authentication

Compile Errors

Bash Errors

PHP Errors

Python pip Errors