Archive for April, 2011

etc/hosts.allow files and IP ranges

Thursday, April 14th, 2011

I’ve inherited a pre-configured box and recently had to audit the etc/hosts.allow files.

For those who don’t know what etc/hosts.allow files are. These are files that services such as vsftp, sshd, and etc, would go to check, to see if certain IPs were allowed or not. If the IP passes the allow rules, then it’s allowed to use the service, otherwise, usage of this service will be DENIED.

Anyways, I’ve found a lot of x.x.x.x/xx rules, and I know their intention. They wanted to allow a range of IPs, in this specific case, they wanted to allow #.#.0.0 to #.#.255.255 where# is a number of a constant value.

Unfortunately, the allows rules didn’t seem to like the /xx format, and the easier solution was simply do #.#. since only the first few octets were interpreted, this allows #.#.x.x values to work, which means provides a #.#.0.0 to #.#.255.255 access. It’s also much easier to read.

Ticketing System vs Google Docs

Monday, April 4th, 2011

When I hear project collaboration, I almost immediately hear “Google Docs” afterwards. Google Docs is great, don’t get me wrong, but for task delegation and project coordination, Google Doc simply isn’t enough.

Let’s say Jack, Jill, Tom, and Bob were all to work on a project.

Here’s the scenario where they collaborate using a ticketing system like BugZilla, JIRA, or etc:

  1. Have a meeting to discuss what exactly the project is about. During the discussion, they’ll break the project down into little bite sized pieces. During this process they also configure the task tracker so that everyone is to be notified when a task is created, changed, assigned, re-assigned, or completed.
  2. They begin to work on the tickets.
  3. When they encounter issue, they make a note of the problem in a form of a “comment” and all the responsible parties are contacted via email.
  4. The party then responds to the email, another email is sent out with the response so nobody else has to and the task is completed.
  5. 2-4 are repeated until the project is complete.


If you were to use Google Docs:

  1. Have meeting over the net, everybody is constantly typing everywhere; they pour out there ideas onto a massively long document. At the end of the meeting, they all agree to start working on the project and go their own ways.
  2. They start working on the project, but they forgot who was delegated what. They scan the document for their task. The task seems to rely on previously discussed segments, so they scan the document for the related sections. They find everything the needed and began working.
  3. They encountered some problems and made notes on this document.
  4. This note goes unnoticed because it’s 3 lines buried inside a 15 page document. The person who worked on it now has to directly contact the person who might know information on this topic. They relay information with each other, and the person working on the task now knows what he needs to know in order to complete the task assigned.
  5. The task lasts a bit longer than expected, and now he has forgotten all the advice he was given. Luckily, it was in email form. Unfortunately, it has been 2 weeks, and it’s now buried in a mountain of spam.
  6. Mining through his spam mountain, he has finally got the gem of information he needed to complete his task.
  7. One of the project members finished his task, and wishes to pick up another task to work on, but someone forgot to strike out a task that is being worked on, or is completed. Feeling helpful this person starts doing the task on the other person’s behalf. Unfortunately, they’re two members working on the project now.

The list goes on…

The point is, in this day and age, with ease and availability of ticketing systems, just use the ticketing system. It’s clean, it’s transparent, and it’s efficient. At least until Google Project Collaborator gets released.