technology, networking and IP telephony
PersonalComputing
I’m going to be rich!
2March 8, 2011
I haven’t received one of these fraudulent email messages in quite a while so I thought I would share with everyone my good fortune. Anyone know what I should spend my new found fortune on first? Perhaps a Motorola Xoom or an Apple iPad2 or maybe a new PC?
ATTN:MCNAMARA,
I am a Trustee and Executor of the estate of a deceased client(Dr P. MCNAMARA) in Budapest, Hungary. I have sat on a 5 year forgotten financial inheritance. In few weeks time, this fund will be transferred to the state as required by law since there’s no claim made. We can both collaborate and share the proceeds 60/40. Your part would be to receive the funds as the beneficiary , since you have the same last name as my late client, and I will prepare the required documents and have it released to you in just days. Please reply this mail stating full name, phone and fax number details if interested. So I can start
the claims process as we build a mutual trust.Many thanks in advance as I look forward to our partnership and trust.
Regards,
Douglas Wild
The message originated from Yahoo China from a Douglas Wild (jd.zainnwild@yahoo.com.cn) with Yahoo user account of (X-RocketYMMF:) jdwild1@att.net.
Cheers!
How to separate the wheat from the chaff?
11February 16, 2011
Your looking to add staff, a network engineer position, but how can you really tell that the candidate isn’t intentionally or unintentionally misrepresenting themselves from a knowledge or skill set perspective? You could look for those three and four letter acronyms right? I’m talking about the following, CCNP, CCNA, CCIE, CISSP, ACA, ACE, NCTS, NCTE, JNCIA, JNCIE, etc. Well unfortunately I’ve seen far too many folks with some of the previously mentioned certifications that don’t really know how to apply what they’ve learned or don’t have enough experience working with large complex networks. I met a CNE (Certified Novel Engineer) about 10 years ago that was booting a Netware 3.12 server from a floppy disk because he didn’t know how to transfer the MSDOS system files to the hard drive, that’s a true story honest! I will be the first to admit that I don’t personally hold any certifications beyond the claim that I’m a QNE (Qualified Network Engineer). That may or may not change in the future for me personally because I do see some value in holding a few professional certifications from a career growth perspective.
With the current very competitive job market and uncertain economic future employers are wary of taking a chance on new employees and want to be sure that they’ve done their homework. I recently received a few inquiries asking how I grade various candidates for highly technical positions. A few years ago I came up with a few non-vendor specific questions that I use when interviewing potential network engineers. The questions are vendor agnostic and are designed to probe the candidates fundamental understanding of how networking actually works (there’s an idea). Having a list of questions ahead of time allows me to be impartial and focus on the task at hand. I leave all the other issues at hand to the recruiter.
There are no absolute right or wrong answers to many of the questions nor is there any scoring metric… instead it helps me understand how strong a particular candidate is in one area or another. I originally had a question on there asking the candidate to describe a 10Base5 network but quickly realized that not too many of us have actually worked with 10Base5 so I dropped it from the list.
Switching
Q. Describe the different between the FDB/MAC and ARP tables and how they are used.
Q. Describe the differences between 802.1p and DiffServ/DSCP.
(Alternate: describe the differences between L2 and L3 QoS mechanisms)
Q. Describe the difference between a Unicast frame and a Multicast frame.
Q. Describe a broadcast storm and its effect on the network.
Routing
Q. Describe the terms OSPF and BGP and how they are used in IP routing.
Q. Describe a black hole route.
Q. Describe the term latency and it’s affect on networking.
Q. Describe the purpose of protocols such as HSRP/VRRP.
Security
Q. Describe how a stateful firewall works?
Q. Describe how a traditional IPSec VPN works.
Q. Describe a SYN flood attack and its affects.
Q. Describe the term NAT and how it’s used in networking.
Q. Describe a proxy server and how it works.
Optical
Q. Describe the term “dB loss” and its impact to network communications?
Q. What is the difference between singlemode and multimode fiber?
Wireless
Q. How many channels are available in 802.11b 2.4Ghz wireless networks in the USA?
Tools
Q. Describe how traceroute and ping work and how they are used in troubleshooting?
Q. What does SNMP stand for and how is it used in networking?
Other
Q. What is the maximum distance for CAT5 UTP cabling?
Q. Describe the term CIDR and what it’s used for.
Q. What is DHCP and describe its operation in the network.
Q. What’s the network mask for a Class B network in CIDR format?
What do you think? Can you answer the majority of questions above? Are you certified?
Cheers!
We systematically reject ‘apache@…’ Huh?
0February 12, 2011
I’m continually amazed by how much hands on effort it takes to run even a small blog or community these days. The SPAM bots are continually spewing their useless garbage everywhere, the hackers and script kiddies are continually trying to break down the front door and somewhere in there is the appreciative reader in search of an answer to his/her question or just genuinely interested in the topic at hand.
Every now and then a genuine (system administration) issue or problem surfaces that deserves some time and effort. Since I’m utilizing a virtual private server (VPS) running CentOS 5.5, I’m responsible for administering and managing the server myself. I was an IBM AIX (long live SMIT) and Solaris System Administrator in a previous life so it’s not a big challenge but it can be a time consuming task. The benefits of managing my own server are still significant enough for me and I’ve learned so much about Linux, MySQL, PHP, Perl, etc. that the experience has been well worth the investment in my view.
I recently noticed that I was getting a lot of bounced email messages on the server from a number of readers that had subscribed to posts on my blog. Here’s a quick snippet of the bounced error message;
Action: failed
Status: 5.1.7
Remote-MTA: dns; mx.acme.org
Diagnostic-Code: smtp; 550 5.1.7 ... We
systematically reject 'apache@...'It seems that a few domains (example above is acme.org – changed to protect identity) were rejecting any email message with the Return-Path set to apache@hostname. In my case the Return-Path was set to apache@michaelfmcnamara.com although the From address was set to noreply@michaelfmcnamara.com. Unfortunately you can’t set (not to my knowledge anyway) the Return-Path from within WordPress administration portal. You need to manually edit wp-includes/class-phpmailer.php and set the variable $Sender to the same email address you setup within WordPress to use as your From address.
/** * Sets the Sender email (Return-Path) of the message. If not empty, * will be sent via -f to sendmail or as 'MAIL FROM' in smtp mode. * @var string */ var $Sender = 'noreply@michaelfmcnamara.com';
With that change complete I can see from the server logs (/var/log/maillog) that the Return-Path is now being properly set.
Feb 12 08:29:56 michaelfmcnamara postfix/pickup[9770]: 2B8FD2C3BB: uid=48 from=<noreply@michaelfmcnamara.com>
Feb 12 08:29:56 michaelfmcnamara postfix/cleanup[11068]: 2B8FD2C3BB: message-id=<67fa95dc7fd22d7c6cfd481d506bfd87@blog.michaelfmcnamara.com>
Feb 12 08:29:56 michaelfmcnamara postfix/qmgr[2647]: 2B8FD2C3BB: from=<noreply@michaelfmcnamara.com>, size=1729, nrcpt=1 (queue active)
Feb 12 08:29:56 michaelfmcnamara postfix/local[11070]: 2B8FD2C3BB: to=<whowhatwhen@michaelfmcnamara.com>, relay=local, delay=0.07, delays=0.04/0.01/0/0.02, dsn=2.0.0, status=sent (forwarded as 321C72C37A)
Feb 12 08:29:56 michaelfmcnamara postfix/qmgr[2647]: 2B8FD2C3BB: removedWith that change those domains that were rejecting email from my server are now accepting them again. Just another day where I’ve learned something new.
Cheers!
Update: Thursday February 24, 2011
It seems the upgrade to WordPress 3.1 has overwritten the change I made in the file… had to update the file again!
Update: Friday April 22, 2011
It seems the upgrade to WordPress 3.1.1 has overwritten the change I made in the file again!
