Citrix Systems make among other things remote access server software which you access with the so-called Citrix Server Client software, downloadable from the installed Citrix server.
This is fine in most instances and most users, where everything works out-of-the-box. When using the Linux versions of the client though, you may get an error message as such:
"You have not chosen to Trust Verisign Class 3 certificate" or something along these lines.
This is the process which will ensure the Verisign Class 3 certificate is trusted:
1) Install Citrix Server ICA client (linuxx86.tar.gz) from the Citrix host
2) Save the Verisign Class 3 Secure Server CA certificate I attach (you may also download this directly from Verisign)
3) Save as/rename it to class3.crt
4) Move this file to your ICAClient/linuxx86/keystore/cacerts folder
5) Try again now, it should work now.
This has been tested with the Kubuntu and openSUSE distros.
Kubuntu xorg.conf: 1680x1050 with NVidia FX series on 22" Samsung Syncmaster 2232BW
Setting a 1680x1050 (widescreen) resolution on Linux is for some reason quite difficult.
Maybe not enough Linux users prefer this resolution for it to be as straightforward to set as for instance 1920x1080 (widescreen) or 1280x1024.
But this is the native resolution of 22 inch monitors, such as the SyncMaster 2232BW by Samsung and having one as such becomes quite a painful experience on too many distros.
The following are taken from the xorg.conf that basically guarantees to get this resolution going. It works on various distros, such as OpenSUSE and Kubuntu. The trick was to remove all other resolutions, forcing this one...
It is geared towards proprietary NVidia FX drivers, so if you do not have one, remove the "Module" and "Driver" sections.
Here are the contents of the /etc/X11/xorg.conf file:
Hopefully this will make your life a little bit more productive.
Maybe not enough Linux users prefer this resolution for it to be as straightforward to set as for instance 1920x1080 (widescreen) or 1280x1024.
But this is the native resolution of 22 inch monitors, such as the SyncMaster 2232BW by Samsung and having one as such becomes quite a painful experience on too many distros.
The following are taken from the xorg.conf that basically guarantees to get this resolution going. It works on various distros, such as OpenSUSE and Kubuntu. The trick was to remove all other resolutions, forcing this one...
It is geared towards proprietary NVidia FX drivers, so if you do not have one, remove the "Module" and "Driver" sections.
Here are the contents of the /etc/X11/xorg.conf file:
Section "Monitor"
Identifier "Generic Monitor"
Option "DPMS"
UseModes "16:10"
HorizSync 30-83
VertRefresh 60
EndSection
Section "Screen"
Identifier "Default Screen"
Device "Configured Video Device"
Monitor "Generic Monitor"
DefaultDepth 24
SubSection "Display"
Depth 24
Modes "1680x1050"
EndSubSection
SubSection "Display"
Depth 16
Modes "1680x1050"
EndSubSection
EndSection
Section "Modes"
Identifier "16:10"
ModeLine "1680x1050 (GTF)" 147.14 1680 1784 1968 2256 1050 1051 1054 1087
EndSection
Section "Module"
Load "glx"
EndSection
Section "Device"
Identifier "Configured Video Device"
Driver "nvidia"
Option "NoLogo" "True"
EndSection
Hopefully this will make your life a little bit more productive.
The IP protocol (Internet Protocol)
The internet protocol is one of the most widely used protocols today. You may not realize it, but you use the IP protocol even at this very instant. To understand how, please see the diagram below. This diagram is usually called the networking stack diagram:
The stacked organisation implies that whenever you use a high level protocol (such as you do now for instance with HTTP -the web protocol), a number of other protocols are actually used which allow for the HTTP protocol to function. Some examples of such protocols would be ARP, DNS, IP, TCP, etc. but of these only IP and TCP are used by HTTP. It is important to clarify that other protocols such as DNS, ARP, etc. are supporting protocols, not used. This will be clarified even further later on, so keep reading.
This is an important observation, because it means if you can capture the packets that describe lower-level protocols, you can effectively analyse/decipher higher level protocols too. Let's focus on the IP protocol, which stands for Internet Protocol.
The Internet Protocol (IP) is the basis of internet-related protocols. It allows for an unreliable way of addressing hosts within a network or even an inter-network (internet), as it is a packet-switching network communications protocol. This is what the structure of an IP network packet looks like:
A number of things of interest can be identified when observing the structure. Every IP packet has one source and one destination address. There are a number of other fields, relating to the correct operation of the IP protocol, including:
The stacked organisation implies that whenever you use a high level protocol (such as you do now for instance with HTTP -the web protocol), a number of other protocols are actually used which allow for the HTTP protocol to function. Some examples of such protocols would be ARP, DNS, IP, TCP, etc. but of these only IP and TCP are used by HTTP. It is important to clarify that other protocols such as DNS, ARP, etc. are supporting protocols, not used. This will be clarified even further later on, so keep reading.
This is an important observation, because it means if you can capture the packets that describe lower-level protocols, you can effectively analyse/decipher higher level protocols too. Let's focus on the IP protocol, which stands for Internet Protocol.
The Internet Protocol (IP) is the basis of internet-related protocols. It allows for an unreliable way of addressing hosts within a network or even an inter-network (internet), as it is a packet-switching network communications protocol. This is what the structure of an IP network packet looks like:
A number of things of interest can be identified when observing the structure. Every IP packet has one source and one destination address. There are a number of other fields, relating to the correct operation of the IP protocol, including:
- Version number
- Flags, signifying various things, such as whether packet fragmentation is allowed
- Header checksum, allowing for header validation
- TTL, i.e. Time-To-Live which describes the maximum number of hops allowed for packets when routed from host to host
The Internet Protocol is itself 'layered' over other hardware protocols, such as Ethernet, 802.11 family protocols, etc. so it is technology independent. Some examples of how addressing works follow:
127.0.0.1 => the local machine (also known as 'localhost')
212.58.226.75 => BBC, news sub-domain (i.e. news.bbc.co.uk)
161.74.14.28 => University of Westminster primary web domain (i.e. www.wmin.ac.uk)
So in other words, the human-friendly names that you use to identify websites and other hosts are artificial and map to one or more IP addressed hosts. To find the IP address of a host, you may use various tools, provided by your operating system, such as ping, traceroute, etc. You may also perform a web WHOIS database query to do so.
IP is the most prevalent protocol for network communications on the internet. Why?
Because it is very mature (birthed in the 80's), it is standardized, it comes for free on all major computing and now some mobile operating systems, it is fast and efficient.
IP is a binary protocol. Examining it using packet sniffing tools such as Wireshark (see related blog post) whilst fetching a web-page yields the image shown on the left. The actual data is shown on the right part of the image, whereas the hex representation is on the left.
Each bit shown on the image on the left corresponds to a different protocol. The cyan bit is 16 bytes in length and contains Ethernet frames (i.e. hardware-related communications data). The yellow bit is IP & TCP protocol data and the red bit is HTTP data.
127.0.0.1 => the local machine (also known as 'localhost')
212.58.226.75 => BBC, news sub-domain (i.e. news.bbc.co.uk)
161.74.14.28 => University of Westminster primary web domain (i.e. www.wmin.ac.uk)
So in other words, the human-friendly names that you use to identify websites and other hosts are artificial and map to one or more IP addressed hosts. To find the IP address of a host, you may use various tools, provided by your operating system, such as ping, traceroute, etc. You may also perform a web WHOIS database query to do so.
IP is the most prevalent protocol for network communications on the internet. Why?
Because it is very mature (birthed in the 80's), it is standardized, it comes for free on all major computing and now some mobile operating systems, it is fast and efficient.
IP is a binary protocol. Examining it using packet sniffing tools such as Wireshark (see related blog post) whilst fetching a web-page yields the image shown on the left. The actual data is shown on the right part of the image, whereas the hex representation is on the left.Each bit shown on the image on the left corresponds to a different protocol. The cyan bit is 16 bytes in length and contains Ethernet frames (i.e. hardware-related communications data). The yellow bit is IP & TCP protocol data and the red bit is HTTP data.Nice collection of security tools
There are numerous security-related tools one can find nowadays on the internet. Furthermore, collections of tools come bundled in all-in-one solutions such as the Linux distro BackTrack.
Sifting through these is not easy, especially if you don't know which one are the most interesting and the most effective. A list of some is included here, feel free to add to the list.
This is not an exhaustive list of penetration testing and such tools by any means. Just a few handpicked utilities and resources that are recommended if not essential for your network's security. Here is the list:
Scanning/mapping tools
Allow you to scan targets, map networks, detect vulnerabilitities: wireshark, kismet, nmap, amap, nessus, satan
Multipurpose/suites
backtrack, cain
SQL Injection/fuzzers
Allow for SQL injections, exploiting poorly designed applications and buffer overflow problems
absinthe, bed
Exploits for privilege escalation
Allow for gaining root/administrator privileges: openssl scanner, metasploit
Defense/detection
Allow for proactively defending from various threats: iptables, snort
Cracking
Allow for making use of resources that are not yours, various tools exist, depending on target: WEP/WPA, Linux, Windows, etc.
Backdoors
Allow for maintaining access after breaking in, without having to break in again: matahari, subseven, SilentDoor, SafeBreaker
Rootkits
Allow for maintaining stealthy access by preventing being detected, various tools for *nix/win32 flavours, browsing this plentiful collection is strongly advised
Forensics
Allow for undeletion of deleted files, partitions and more: sleuthkit, foremost
Sifting through these is not easy, especially if you don't know which one are the most interesting and the most effective. A list of some is included here, feel free to add to the list.
This is not an exhaustive list of penetration testing and such tools by any means. Just a few handpicked utilities and resources that are recommended if not essential for your network's security. Here is the list:
Scanning/mapping tools
Allow you to scan targets, map networks, detect vulnerabilitities: wireshark, kismet, nmap, amap, nessus, satan
Multipurpose/suites
backtrack, cain
SQL Injection/fuzzers
Allow for SQL injections, exploiting poorly designed applications and buffer overflow problems
absinthe, bed
Exploits for privilege escalation
Allow for gaining root/administrator privileges: openssl scanner, metasploit
Defense/detection
Allow for proactively defending from various threats: iptables, snort
Cracking
Allow for making use of resources that are not yours, various tools exist, depending on target: WEP/WPA, Linux, Windows, etc.
Backdoors
Allow for maintaining access after breaking in, without having to break in again: matahari, subseven, SilentDoor, SafeBreaker
Rootkits
Allow for maintaining stealthy access by preventing being detected, various tools for *nix/win32 flavours, browsing this plentiful collection is strongly advised
Forensics
Allow for undeletion of deleted files, partitions and more: sleuthkit, foremost
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