Commands by viner (3)

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Drop or block attackers IP with null routes
Someone might attack on your system. You can drop attacker IP using IPtables. However, you can use route command to null route unwanted traffic. A null route (also called as blackhole route) is a network route or kernel routing table entry that goes nowhere. Matching packets are dropped (ignored) rather than forwarded, acting as a kind of very limited firewall. The act of using null routes is often called blackhole filtering.

List of reverse DNS records for a subnet
This command uses nmap to perform reverse DNS lookups on a subnet. It produces a list of IP addresses with the corresponding PTR record for a given subnet. You can enter the subnet in CDIR notation (i.e. /24 for a Class C)). You could add "--dns-servers x.x.x.x" after the "-sL" if you need the lookups to be performed on a specific DNS server. On some installations nmap needs sudo I believe. Also I hope awk is standard on most distros.

Remove spaces from filenames - through a whole directory tree.
Sometimes, you don't want to just replace the spaces in the current folder, but through the whole folder tree - such as your whole music collection, perhaps. Or maybe you want to do some other renaming operation throughout a tree - this command's useful for that, too. To rename stuff through a whole directory tree, you might expect this to work: for a in `find . -name '* *'`;do mv -i "$a" ${a// /_};done No such luck. The "for" command will split its parameters on spaces unless the spaces are escaped, so given a file "foo bar", the above would not try to move the file "foo bar" to "foo_bar" but rather the file "foo" to "foo", and the file "bar" to "bar". Instead, find's -execdir and -depth arguments need to be used, to set a variable to the filename, and rename files within the directory before we rename the directory. It has to be -execdir and won't work with just -exec - that would try to rename "foo bar/baz quux" to "foo_bar/baz_quux" in one step, rather than going into "foo bar/", changing "baz quux" to "baz_quux", then stepping out and changing "foo bar/" into "foo_bar/". To rename just files, or just directories, you can put "-type f" or "-type d" after the "-depth" param. You could probably safely replace the "mv" part of the line with a "rename" command, like rename 'y/ /_/' *, but I haven't tried, since that's way less portable.

Shows what processes need to be restarted after system upgrade
This command can be installed in debian by the package debian-goodies. It also outputs the /etc/init.d/ commands that you need to do.

Record output of any command using 'tee' at backend; mainly can be used to capture the output of ssh from client side while connecting to a server.
Optionally, you can create a new function to do this with a custom command. Edit $HOME/.bashrc and add: myssh () { ssh $1 | tee sshlog ; } Save it. At command prompt: $ myssh user@server

Shows space used by each directory of the root filesystem excluding mountpoints/external filesystems (and sort the output)

RTFM function
RTFMFTW.

Play Mediafile in multipart RAR archive on the fly with buffer to seek back and forth
Fire this up in the directory of the RAR achived files to watch any archived movie tv-show or other media without having to unpack it. I also added a cache/buffer to be able to seek back and forth.

Which processes are listening on a specific port (e.g. port 80)
swap out "80" for your port of interest. Can use port number or named ports e.g. "http"

ignore .DS_Store forever in GIT
With a couple of little commands, you?ll be able to ignore the .DS_Store files forever from your git repositories on mac! The following command will add the .gitignore file to the git configuration git config --global core.excludesfile ~/.gitignore then, the following, will add the .DS_Store to the list echo .DS_Store >> ~/.gitignore


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