Archive for the ‘Security’ Category:
Any… good… php devs out there looking for some side work?
apokalyptik apokalyptik com — Subject: “PHP Consulting” (I’ll likely completely overlook your mail if you use some subject not starting with that string)
Cheers
DK
Subscribe to the comments for this postThis cold of mine just WILL NOT quit…
ORACLE VISTA!”
Trying out NoListing
Down with HTML E-Mail!
I’m with Jeremy on this one… Lets face it, e-mail is broken. We have long since outgrown it, we have been living with the pains of ot for a long time now. It’s everyones favorite internet whipping boy. “I hate spam” “I hate stupid forwards” “I hate huge attachments”. We spend all our time bitching about e-mail but them when something happens it’s “the sky is falling the sky is falling give me back my good sweet innocent e-mail the way it was before you broke it! It was JUST FINE THE WAY IT WAS WHY DID YOU HAVE TO CHANGE IT?!”
Go whine to somebody else, seriously. EMail is the black plague of the internet, its an infectious disease, a self sustaining spiral down the drain of absurdity. I, for one, will be happy when all of the people who depend on it, and who enable it, and who empower it finally go retire on some island somewhere and the kids take over and it’s all about text messaging, not e-mail.
Speaking of kids taking over: “SUCKS TO YOUR EMAIL!”
End rant
BWUahahahahaha
Loosing your old standby browser: $0
Hoping you can use your machine after the next reboot: $0
Getting to be the QA engineer for one of the richest companies ever: PRICELESS
QMAIL-TOASTER remote redilivery loop problem
A lot of the core technological things that it did were done in basically the same way that I would have done them manually (which is bidirectionally gratifying for me) and there are some bells and whistles that are *nice* but I wouldn’t have bothered setting them up on my own (e.g. qmailmrtg graphical log analysis.)
I did (hopefully did and not still do) have one oddball problem with it. After switching over there were certain servers from which I would continuously get the same message over and over from. Everything in my logs showed a successful delivery, and its not as though the messages were stuck in my queue either, the remote servers would actually reconnect and deliver the message again.
Well for a while I had better things to do with my scant time than deal with this one inconvenient (but not critical) issue. Well today I finally cracked. Its probably because I’ve now gotten one particular message something on the order of 30 times now. Thinking about the problem, and examining my logs it seemed that the only time this happened was when a message was processed by simscan for viruses (clamd) and spam (spamd) at the SMTP transmission level. But that was not the complete story because other messages from other servers did not have this problem even though they went through simscan as well.
On a hunch I figured that the sending mail server was probably only designed to wait X number of seconds (or microseconds) after the finished transmission before expecting to get a status code back from my SMTP daemon. If it takes too long then the remote sending server might just assume the connection was lost and re-queue the message for redelivery. So I disabled spam and virus scanning in simscan
#echo ":clam=no,spam=no,spam_hits=12,attach=.mp3:.src:.bat:.pif" \ > /var/qmail/control/simcontrol # /var/qmail/bin/simscanmk # /var/qmail/bin/simscanmk -g # qmailctl restart
And the problem *seems* to have gone away. I’m not worried about viruses at this point because I’m running OSX as my desktop, and Thunderbird is usually pretty good about spam… so… no loss for me there.
I’m mainly writing this down here so that if someone were to have this problem, and floundering while searching for an answer, they might have a better chance of finding a helpful hint. Searching for things like redelivery and mail loops on google will yield nothing of any value at present.
Cheers
DK
Series: CRM on S3 & EC2, Part2
There is an important caveat to this information: Nobody has done this enough to really have a set of scalable one-size-fits-all tools (or a tool chain) fit for the job… You’ll have to be OK with doing some in-house experimentation. And be OK with the idea of maybe making a couple of miss-steps along the way. As is the case with any new (OK new to YOU) technologies there are some things you just have to learn as you go.
To setup a system that is fault tolerant, and to develop a system in which you manage your risks requires a balance of acceptable versus unacceptable trade off situations. Your main types of backups are as follows:
A) Simple local backup. your old stand-by tar and his friends bzip2, gzip, and even compress. They’ve been doing backups since backups were backups (or almost anyhow) and they are good friends. In this kind of a situation they aren’t the whole solution but you can bet your butt that they’re a part of it.
B) Hard-Copy backup. This isn’t what you want, but worth mentioning. This kind of backups consists of hard disks, tapes, CDs DVDs, etc, which are copied to and then physically removed from the machine. The advantage to this type of backup is that you can take them offsite incase of a local disaster, but in an EC2+S3 business there is no such thing as a local disaster. So if you, once per week/month/whatever, just copy down your latest backups from S3 that should suffice.
C) Copy elsewhere backup. This is going to be bread and butter for the bulk of the solution. It’s not the entire solution. But it’s a fairly big piece. In this case S3 is your “elsewhere”
D) Streaming backups. Examples of streaming backups are MySQL’s replication, or pushing data into an Amazon SQS pipe for playback at a later point. Also a key player in what will surely be your ending strategy.
Well that was fun. Learning just enough to be dangerous but not enough to actually do anything… And certainly not enough to answer the question. So lets get to it.
You will have two distinct areas of backup which will be important to you. You have the UI end, and the DB end. Both these sections should be approached with different goals in mind, because the usage pattern on them ends up being different.
The Front End
You’ve no doubt got a development environment setup somewhere, and as you make bug fixes to this environment, or add features, or change layouts to announce your IPO, or whatever you need to push a snapshot to your servers *AND* any new servers you bring up need to have the new UI code and not the old UI code.
For the sake of argument, here, I’ll assume that you have a SVN or CVS server which holds your version-controlled code (you *ARE* using version control right?) So your build process should, ideally, update the stable branch on your Revision Control Server, and send out a message to your UI servers that an update is available. They should then download the new code from RCS to a temporary directory, and once there you pull the fast-move trick:
$ mv public_html public_html.$(date +%s) && mv public_html.new public_html
At this point all of your UI servers received the message at the same time, and update at the same time. Any new server should have, in its startup scripts sometime after the network is brought up, a process which performs the above update before even bringing up your HTTP service.
And that was the easy part… Now for MySQL
As for MySQL, I’ve outlined my thoughts on that here already in my article: MySQL on Amazon EC2 (my thoughts) Which options you choose here depend on a couple of things: First the skill level of the people who will be implementing the entire procedure *AND* the skill level of the people who will be maintaining it (if those people aren’t the same people). But one very serious word of caution: Whatever you do stop thinking of an EC2 instance as 160GB of space for MySQL and start thinking of it as 60Gb (70GB MAX) because backing up something that you do not have the space to copy is a difficult task which normally required bringing things offline — trust me on this.
My gut feeling for you is that if you owned/rented one physical server to be your write server for your database setup. something roughly equal to the specs of the EC2 virtual machine, except with 320Gb of disk space. That would be your best bet for now. You could keep your replication logs around for the entire history of your database… for a while
You also should keep one extra MySQL instance (on EC2 if you like) up and running for the sole purpose of being up to date. You would then periodically turn it off and copy the entire thing up to S3. So that when you had to restore a new instance you would simply copy those files down, assign the server-id, and let it suck everything new down via replication.
The gotcha here is that this wont last forever… at least not on one database. There will come a time, if you get a “lot” of usage, when the process of downing a server copying it, copying it, bringing it up and waiting for replication will become infeasible. It will eventually just stop adding up. It’s at that point you will have to make a couple of careful choices. If you have properly laid out your schema you can pull your single monolithic database apart, distribute it amongst several database clusters, and carry on as you have been. If you have properly laid out your schema in a different way you will be able to assign certain users to certain clusters and simply write a migration tool for moving users and their data around between database clusters. If you have not properly laid out your data you can choose whether to spend time and money re-working your application to make it right. Or you can spend time and money on buying big “enterprise class hardware” and give yourself time to make things right.
Unless you can truly count on being able to bleed money later on. You’ll VERY CAREFULLY consider your schema now. It will make all the difference. And if you end up with 2+TB of data which is completely unmanageable… well don’t say I didn’t warn you… Those kinds of optimizations may seem silly now when you’re only expecting 5-25GB of data but they wont be silly in 2-4 years.
Dude, You’ve been hacked!
While investigating a breakin on a freinds server I came across this pretty damn cool little utility: The RootKit Hunter
It’s a spiffly little piece of work, and it helped considerably. This server, for reasons I can’t say, couldnt be simply wiped and reloaded in a short time span… and HAD to, for a particular service that it performed, stay up for the duration of the week. This little tool helped considerably in cleaning the server out relatively well.
Still, when possible, wipe and reload after a hack attempt is the BEST choice. Cleaning is an imprecise art at best.
Captcha
Cheers
DK