X-Forwarded-For log filtering

The “X-Forwarded-For” is a HTTP header commonly used to pass the original client ip address as the web request traverses through reverse proxy servers. Furthermore, to truly capture the request ip address, the web server must be configured to record the ip address from the X-Forward-For header. If not, the log file will simply show that all requests are coming from the reverse proxy servers that frontend the web servers. (more…)

Configuring Sendmail to relay through Gmail SMTP

Sending email directly from the MTA (mail transfer agent) on one’s server is now considered to be faux pas. Unless you’ve got that machine configured within DNS (MX record, reverse lookup, etc), it’d likely fail most basic spam checks at the destination mail server. The complexity of the configuration increases if you’ve got the need to masquerade emails from multiple domains. (more…)

mutt: changing sender mail address on the fly

Had a need today to adjust the sender email address for a notification script. Since the script uses mutt to send the emails, that change was fairly straight-forward. Instead of modifying .muttrc, simply export the EMAIL environmental variable. (more…)

Cron / Crontab – disable e-mail notifications

There are 2 ways to prevent cron to send out e-mail notifications after jobs are run:

1. Ensure there are no output from the script(s) being run by sending the output to /dev/null
   Simply append one of the following directives to the end of your script.

   >/dev/null 2>&1.

   OR

   &> /dev/null

   Your crontab would now look something like:

   0 1 5 10 * /path/to/script.sh >/dev/null 2>&1

   OR

   0 1 5 10 * /path/to/script.sh &> /dev/null

(more…)

‘vi’ quick command references

I’m a die hard vi user and still prefer using vi to edit plaintext files. There were some discussion on twitter on vi awhile back and I thought I’d share my own command cheat sheet for vi in edit mode. This is not quite a full tutorial but makes for a useful reference.

Editing Text…

i Insert before cursor
I Insert before line
a Append after cursor
A Append after line
o Open a new line after current line
O Open a new line before current line
r Replace one character
R Replace many characters
x Delete character to the right of cursor
X Delete character to the left of cursor
D Delete to the end of the line
dd Delete current line
:d Delete current line
yy Yank the current line
p Put after the position or after the line
J Join lines
u Undo last change

Moving the cursor around… (more…)