Pages from my notebook
Posted in Linux on May 20th, 2015
Trivial to create: ahoward@martlet[~]$ mkfifo pipe1 ahoward@martlet[~]$ ls -l pipe1 prw-r–r– 1 ahoward ahoward 0 May 19 22:16 pipe1 ahoward@martlet[~]$ A bit trickier to use: ahoward@martlet[~]$ echo test > pipe1 (hangs…) ^C ahoward@martlet[~]$ cat pipe1 (also hangs…) Any attempt to read or write from the pipe hangs. The problem here is that a […]
By default, a linux machine will drop traffic that’s not destined for an IP bound locally. If you’re planning on receiving traffic not ultimately destined for you (ie: you’re behaving as a router along the path to the ultimate destination), then you’ll need to flip a couple flags in /etc/sysctl.conf to allow traffic forwarding: net.ipv4.ip_forward […]
Posted in Technical on Mar 5th, 2010
Here’s how a sender verification callout works. Let’s say I’m an innocent mail server, and some jerk is trying to send me a message. There’s a very strict procedure for how mail servers talk to each other. Here’s an example, with the sender’s (1.1.1.1) stuff in red, the receiver’s (2.2.2.2) stuff in blue, and an […]
Posted in Technical on Mar 4th, 2010
Buy a domain.Any registrar will do. If someone else is going to host the DNS for your domain, skip to step 4. Otherwise, continue from here. The next few steps are how you make sure the registrar knows your server exists as a nameserver. Until the registrar is aware of your server’s existence, no domains […]
Posted in Technical on Nov 4th, 2009
Despite the fact that it’s really not all that difficult, no one understands DNS. As such, it’s probably a good thing that you don’t need to understand DNS to properly configure reverse DNS for your server. So you’ve got a server up on an IP (1.2.3.4, for example) and now you need to set reverse […]
A lot of Windows services love to create log files (IIS for example), but when it comes to log rotation in Windows, the functionality is glaringly absent. In linux it’s as easy as “tmpwatch –mtime 24”. In Windows there actually is a solution, but it’s a bit more complicated. For Windows 2000 you’ll need to […]
If you have a mail server installed it’s pretty easy. Every mail server is going to provide a sendmail binary, so that’s what we’ll use. The bare minimum is as follows: sendmail -t <<EOF To: [email protected] Subject: Test Body . EOF That’s probably not going to reach the destination, however. The problem with this is […]
My last post described in detail the steps to effectively block all network traffic from an attacking IP. Here’s how to block an IP in linux: iptables -A INPUT -s IP-To-Block -j DROP iptables -A INPUT -d IP-To-Block -j DROP Of course, that takes advantage of the built-in linux firewall. We didn’t use the built-in […]
There’s probably a better way to do this – if you know of one, please comment on this post. I have a pretty high opinion of myself, but I’m not so stubborn as to think I already know the best way to do everything. Firewall options for a Windows server are kind of sparse. I’ve […]
Granted, some of these are probably SSH or Putty hot-keys. I’m not certain there’s going to be a “Bash hot-keys 2” post, but there are probably plenty of combinations I’ve forgotten or have yet to learn, so we’ll call this post part 1, and there will most likely be more. ctrl+l That’s a lowercase L. […]
RootMyPC
Pages from my notebook
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