I have seen a few “staying safe online” guides lately. I wrote one of my own a while back after some of my friends were threatened online and got worried. This guide should be a good starting point for most common casual internet users. It’s important to remember that no matter what you do if it’s online, it can be hacked.
- Never reuse passwords
- Some websites are easier to hack than others
- Hackers will try the same password on other websites
- Use LastPass for easier management
- Don’t use simple passwords
- Hackers guess passwords all the time
- There are easy automatic tools that enumerate all password options
- Don’t use your name, birthday, SSN, or any public information in passwords
- Keep your computer & phone up-to-date
- Old software has known and easily exploitable vulnerabilities
- Never click links in emails
- Clicking the wrong link can give control of your accounts to hackers
- Manually browse to the website even if the email looks legit
- Always logout on public computers
- Preferably never login on public computers in the first place
- Data can be linger even after logging out
- Some public computers record your passwords
- If it was put online, it will stay online
- Any private information shared can help hacking
- Your name and birth year can be enough to guess your SSN
- Click the little lock icon on top and follow instructions
- Set everything to private
- Hide your birth year
- Click the little triangle on the top right and choose Settings
- Enable login alerts to be notified of hacks
- Enable login approvals
- Enable trusted contacts in case your account is hacked
Securing Google Account
- Enable 2 factor authentication
- Check Google+ privacy
I had a problem where HDFS would fill up really fast on my small test cluster. Using
hdfs dfs -du I was able to track it down to the MapReduce staging directory under
/user/root/.staging. For some reason, it wasn’t always deleting some old job directories. I wasn’t sure why this kept happening on multiple clusters, but I had to come up with a quick workaround. I created a small Python script that lists all staging directories and removes any of them not belonging to a currently running job. The script runs from cron and I can now use my cluster without worrying it’s going to run out of space.
This script is pretty slow and it’s probably possible to make it way faster with Snakebite or even some Java code. That being said, for daily or even hourly clean-up, this script is good enough.
all_jobs_raw = subprocess.check_output(
'mapred job -list all'.split())
running_jobs = re.findall(
staging_raw = subprocess.check_output(
'hdfs dfs -ls /user/root/.staging'.split())
staging_dirs = re.findall(
stale_staging_dirs = set(staging_dirs) - set(running_jobs)
for stale_dir in stale_staging_dirs:
'hdfs dfs -rm -r -f -skipTrash ' +
'/user/root/.staging/%s' % stale_dir)
The script requires at least Python 2.7 and was tested with Hadoop 2.0.0-cdh4.5.0.
Sometimes you get stuck with a broken or no dump at all. You know what you’re looking for but WinDBG just keeps refusing to load symbols as you continue to beg for mercy from the all knowing deities of Debugging Tools for Windows. You know what PDB you’re looking for but it just wouldn’t load. The only thing you do know is that you don’t want to go digging for that specific version of your product in the bug report and build a whole setup for it just so you can get the PDB. For those special times, some WinDBG coercion goes a long way.
To download the PDB create a comma separated manifest file with 3 columns for each row. The columns are the requested PDB name, its GUID plus age for a total of 33 characters and the number 1. Finally call symchk and pass the path to the manifest file with the /im command line switch. Use the /v command line switch to get the download path of the PDB.
To demonstrate I’ll use everyone’s favorite debugging sample process.
C:\>echo calc.pdb,E95BB5E08CE640A09C3DBF3DFA3ABCB42,1 > manifest
C:\>symchk /v /im manifest
SYMSRV: Get File Path: /download/symbols/calc.pdb/E95BB5E08CE640A09C3DBF3DFA3ABCB42/calc.pdb
DBGHELP: C:\ProgramData\dbg\sym\calc.pdb\E95BB5E08CE640A09C3DBF3DFA3ABCB42\calc.pdb - OK
SYMCHK: FAILED files = 0
SYMCHK: PASSED + IGNORED files = 1
To force load the PDB you need to update the PDB path, turn SYMOPT_LOAD_ANYTHING on, and use the .reload command with /f to force and /i to ignore any so called mismatches.
kd> .sympath C:\ProgramData\dbg\sym\calc.pdb\E95BB5E08CE640A09C3DBF3DFA3ABCB42
kd> .reload /f /i calc.exe=0x00400000
You should now have access to all the data in the PDB file and stack traces should start making sense.
An open source OS makes debugging applications so much easier. Instead of firing up IDA and going through opcodes, you can simply read the code and sometimes even find comments. However, searching through millions of lines of code can be a daunting task. Operation systems usually have a huge codebase and even the simple task of looking for one function can take a few good minutes. After reading that function, you usually want to search for functions it calls or functions that call it to better understand the flow. Those extra searches take time too. A good IDE would solve this issue but it requires downloading and indexing the massive source code first.
LXR was created for this exact reason. It allows hosting a fully indexed copy of the source code. It even makes it easy to publish an index of multiple versions of the source code. Want to compare a certain function between two versions of the Linux kernel? No problem. Want to know which functions use a certain function? Easy. LXR is awesome and fast.
Setting up LXR on your own, however, does take some time and effort. That is why I was happy to find AndroidXref.com while trying to hunt down a bug in one of my Android applications. It indexes both Android and patched Linux kernel sources for all major versions of Android. It is an invaluable resource every Android developer should know.
I originally had a question about this topic open on StackOverflow with AndroidXref as the accepted answer. It was recently deleted, probably because it didn’t have anything to do with C operator precedence. This is my
I created a quick backport patch for Scapy 2.2.0 so it could run on Python 2.4. Nothing too special. Just the usual removal of with, try/except/finally and defaultdict.
So if you’re stuck with Python 2.4 like me but still want to [ab]use Scapy, apply the patch and get your fuzz on.
The original ticket is available on Scapy Trac.
Newer versions of GDB come with the nifty find command. The old version of GDB I have to use does not. It is also incapable of generating a proper stack trace for the platform it supposedly serves. But that’s a whole other story…
Anyway, I found a piece of code that almost does the same. I tweaked it a bit, fixed the stray bug ($x -> %p) and would like to never do it again. So here it is for my future reference and your indulgent.
set $start = (uint64 *) $arg0
set $end = $start + $arg1
set $pattern = (uint64) $arg2
set $p = $start
while $p < $end
if (*(uint64 *) $p) == $pattern
printf "pattern %p found at %pn", $pattern, $p
Humanoid, search engine and one of the most addictive FPS games ever created walk into a bar. A few refreshing cups of coffee later, a joke is born and its name is MW2 Guide.
I’ve created a pretty simple application for Android that helps Call of Duty: Modern Warfare 2 addicts, such as myself, to make some sense of the bombardment of dialog boxes popping after a match. It’s basically a list of all available callsign titles and their description. What sets it apart from a few dozen similar apps is the quick search ability and auto completion voodoo, in accordance with Android’s search centric vision.
Search for MW2 Guide on the market, or use the QR code below.