Install Packages

Open the terminal client and sudo to root and then remount the root file system read-write:

sudo -i
mount -o rw,remount /

As root update the package list and install some additional packages (you can use apt-cache search to find packages):

apt-get update
apt-get install cryptsetup git vim lynx screen subversion \
                iptables-persistent whois nmap arp-scan mosh \
                dnsutils wget privoxy

Note it is important not to do apt-get upgrade as this could break things.

To return the phone root file system to being read-only you probably need to reboot the phone.

After the phone system has been upgraded using the GUI you will need to repeat the steps above, so to make this easier you can put the above into a ~/.bash_aliases file, for example:

#!/bin/bash

# Mount the root file system read-write
alias mnt-root-rw='sudo mount -o rw,remount /'

# Install some extra packages and set vim as the
# default editor (edit this list as you wish)
alias apt-install-essential='sudo apt-get update ; sudo apt-get install cryptsetup git vim lynx screen subversion iptables-persistent whois nmap arp-scan mosh dnsutils wget;

Then after upgrading you can simply run:

mnt-root-rw
apt-install-essential

Note that after creating a ~/.bash_aliases you need to source it before the aliases will work (or open a new terminal):

source ~/.bash_aliases