Archive
Back to the grind – SSH Multiplexing – say wha?????
So, It’s been quite a while since I posted anything on this blog. Thought I would get back into the swing of things. I have tons of updates but lately very little time. I think I’ll try to dedicate at least an hour a week to get something up here if not more.
For now, thought I would add to the latest linux tips n tricks I use to post.
SSH Multiplexing
I knew about this for quite a while but never really used it, lately for the past few months it’s been a life saver. On avg during the course of my workday, I’m accessing 5-10 systems. This results to an ugly infestation of terminal windows, which surprisingly I have mastered the art of organizing thanks to tmux.
Anyways, what this allows you to do is use 1 TCP connection for each server you connect into. Any additional SSH requests created from your client will use existing connection already established. Cutting your login time in half.
Modify your existing ~/.ssh/config file and add the following:
Host * ControlMaster auto ControlPath ~/.ssh/master-%r@%h:%p
ControlMaster auto tells ssh to try to start a master if none is running, or to use an existing master otherwise. ControlPath is the location of a socket for the ssh processes to communicate among themselves. The %r, %h and %p are replaced with your user name, the host to which you’re connecting and the port number—only ssh sessions from the same user to the same host on the same port can or should share a TCP connection, so each group of multiplexed ssh processes needs a separate socket.
That’s it!!!
To test this, initiate a single ssh connection to any server. In a new window create another ssh connection to the same server. You should immediately see a difference the 2nd time around.
I would like to thank the Linux Journal for this cool tip, I had a 5 year old bookmark that I stumbled over a few months back that got me hooked. You can find it Here
For now, I’m off, check back later.
f.lux screen temp adjustment
It’s been a while since I have posted here, but I thought it best to pick it up again 🙂
A few weeks ago I found this website that adjusts your screen temp to accommodate the time of day. Here is a quick description below:
f.lux fixes this: it makes the color of your computer’s display adapt to the time of day, warm at night and like sunlight during the day.
It’s even possible that you’re staying up too late because of your computer. You could use f.lux because it makes you sleep better, or you could just use it just because it makes your computer look better.
Check it out @
Just to clarify this does work on Ubuntu / Raring, I’ve also installed it to my Windows and random laptops around the home. When working late night, your eyes don’t feel like they are being burned out of your head from staring at the computer screen.
Try it out!
Ubuntu 13.04 now available for the Google Nexus 7
Hey All,
Nexus7 Running Raring 13.04
Today was the official announcement for the Nexus 7 supporting 13.04, for all you Nexus7 users that may have missed todays ubuntu meeting on Freenode.
This week we announced that the 13.04 build is available for download. New features include:
Added the oem installer, so no more preinstalled images!! Users can select their desired Language / Time Zone and Username
The ubuntu-installer-nexus7 was recently updated to rev 1.7 , this new version now flashes the 13.04 daily builds
For those of you that may not have the installer, you can go grab it @ https://launchpad.net/~ubuntu-nexus7/+archive/ubuntu-nexus7-installer
If some of you want to dist-upgrade from 12.10 -> 13.04 then you may hit some known issues.
Please refer to the following bugs:
http://pad.lv/1087295
http://pad.lv/1087335
These are the only bugs I found when dist-upgrading. We are urging everyone to re-flash if you don’t want to deal with the workarounds.
Serial Debug is a new feature that was recently added for 13.04, to enable and use, simply plug the usb cable into the Nexus7, connect to your computer and via a terminal type:
- “screen /dev/ttyACM0 115200”
This should drop you into a login prompt. To kill, issue “ctrl-a k”
Refer to the wiki for more info @ https://wiki.ubuntu.com/Nexus7/
Enjoy!
-Sean
Generating a clean MD5 Sum check file in python3
This week I was stuck on a small problem involving me to generate hash sums for validation. Since I’ve been working on a automation project at work focusing on creating 100% hands free testing tools. A part of my test called for some basic procedures but I wanted to verify that the integrity of the data was sane. The original script that I was updating was written in Bash. Pretty much straight forward but yet, still room for improvement! I decided to revise the script and convert it over to python, doing so would also make a more powerful tool giving the versatility that python has over simple bash scripts. src and dst are 2 parameters that are called elsewhere in the script. Essentially they are strings pointing to a path on your hard disk, for example dst = “/tmp/blah/blah/”
def prepimage(src, dst):
'''
Obtain sample files
'''
filename = "%s/md5sum.txt" % (dst)
md5path = "%s/" % (dst)
print ("Copying data and Generating md5sums")
if not os.path.exists(dst):
shutil.copytree(src, dst)
#Generate md5sums
list = subprocess.check_output(["ls", dst],universal_newlines=True)
plist = list.split('\n')[0:2]
f = open(filename, "wt")
for item in plist:
out = subprocess.Popen(['md5sum', item], universal_newlines=True\
, stdout=subprocess.PIPE, cwd='%s' % dst).communicate()[0]
f.write(out)
f.close()
return 0
Lines 7 – 9 are simply creating my directory if it doesn’t exist.
We start @ Line 12,
list = subprocess.check_output(["ls", dst],universal_newlines=True)
plist = list.split('\n')[0:2]
Using subprocess.Popen we kick of an “ls” command. dst is an argument that we set earlier pointing to a random directory. This will now give us output of something like this:
‘How fast.ogg\nJosh Woodward – Swansong.ogg\nmd5sum.txt\n’
the 2nd line will split the string using the delimiter \n to give us:
[‘How fast.ogg’, ‘Josh Woodward – Swansong.ogg’]
Now using this list, we can create a new file as I do in 14 and kick off a for loop to run md5sum against each entry in the list and write the output to our new file. The final output will look just like this:
cat /tmp/optical-test/Ubuntu_Free_Culture_Showcase/md5sum.txt 6e34a2a0eaa61748ba3a33015a84e813 How fast.ogg c9459a907b9345b289ba6c9e6517d4c2 Josh Woodward – Swansong.ogg
On the flip side, you can automate the integrity check by creating a new function and adding:
#Verify md5checksum checkoutput = subprocess.Popen(['md5sum', '-c', 'md5sum.txt'] , universal_newlines=True, stdout=subprocess.PIPE\ , cwd='/media/CDROM/').communicate()[0]
Which should output:
How fast.ogg: OK
Josh Woodward – Swansong.ogg: OK
—————————————————————————————–
Python 3 also makes use of hashlib to generate the hashsum.. If you don’t need a checksum file then heres some alternate code you can use!
import hashlib ... ... filename = "/tmp/file1.txt" ... file = open(filename, 'rb') filedata = file.read() file.close() md5 = hashlib.md5() md5.update(filedata) md5sum = md5.hexdigest() print (md5sum)
This would generate just the hashsums:
6e34a2a0eaa61748ba3a33015a84e813
c9459a907b9345b289ba6c9e6517d4c2
Connecting to an IRC server behind a firewall? I feel your pain!
So I use Xchat daily and connect to a private IRC server to talk with my colleagues. I also have a BIP server in the office to record all of the IRC transcripts, this way I never miss any conversations regardless of the time of day. Because the BIP server is behind a firewall on the companies network I can’t access it from the outside. For the past year I’ve been working around this by connecting to my companies firewall via ssh and creating a SOCKS tunnel then simply directing xchat to talk through my local SOCKS proxy.
To do this , open a terminal and issue:
ssh -CND <LOCAL_IP_ADDRESS>:<PORT> <USER>@<SSH HOST>
Ex: ssh -CND 192.168.1.44:9999 sfeole@companyfirewall.com
Starting ssh with -CND:
‘D’ Specifies a local “dynamic” application-level port forwarding. This works by allocating a socket to listen to port on the local side, optionally bound to the specified bind_address. It also adds compression to the datastream ‘C’ and the ‘N’ is a safeguard which protects the user from executing remote commands.
192.168.1.44 is my IPv4 address
9999 is the local port i’m going to open and direct traffic through
After the SSH tunnel is open I now need to launch xchat, navigate to Settings -> Preferences -> Network Setup and configure xchat to use my local IP (192.168.1.44) and local port (9999) then press OK then Reconnect.
I should now be able to connect to the IRC server behind the firewall. Usually I run through this process a few times a day, so it becomes somewhat of a tedious annoyance after a while.
Recently I finished a cool python3 script that does all of this in quick command.
The following code will do the following:
1.) identify the ipv4 address of the interface device you specify
2.) configure xchat.conf to use the new ipv4 address and port specified by the user
3.) open the ssh tunnel using the SSH -CND command from above
4.) launch xchat and connect to your server (assuming you have it set to auto connect)
To use it simply run
$./xchat.py -i <interface> -p <port>
ex: $./xchat.py -i wlan0 -p 9999
the user can select wlan0 or eth0 and of course their desired port. When your done with the tunnel simply issue <Ctrl-C> to kill it and wala!
https://code.launchpad.net/~sfeole/+junk/xchat
#!/usr/bin/env python3
#Sean Feole 2012,
#
#xchat proxy wrapper, for those of you that are constantly on the go:
# -------------- What does it do? ------------------
# Creates a SSH Tunnel to Proxy through and updates your xchat config
# so that the user does not need to muddle with program settings
import signal
import shutil
import sys
import subprocess
import argparse
import re
import time
proxyhost = "myhost.company.com"
proxyuser = "sfeole"
localusername = "sfeole"
def get_net_info(interface):
"""
Obtains your IPv4 address
"""
myaddress = subprocess.getoutput("/sbin/ifconfig %s" % interface)\
.split("\n")[1].split()[1][5:]
if myaddress == "CAST":
print ("Please Confirm that your Network Device is Configured")
sys.exit()
else:
return (myaddress)
def configure_xchat_config(Proxy_ipaddress, Proxy_port):
"""
Reads your current xchat.conf and creates a new one in /tmp
"""
in_file = open("/home/%s/.xchat2/xchat.conf" % localusername, "r")
output_file = open("/tmp/xchat.conf", "w")
for line in in_file.readlines():
line = re.sub(r'net_proxy_host.+', 'net_proxy_host = %s'
% Proxy_ipaddress, line)
line = re.sub(r'net_proxy_port.+', 'net_proxy_port = %s'
% Proxy_port, line)
output_file.write(line)
output_file.close()
in_file.close()
shutil.copy("/tmp/xchat.conf", "/home/%s/.xchat2/xchat.conf"
% localusername)
def ssh_proxy(ProxyAddress, ProxyPort, ProxyUser, ProxyHost):
"""
Create SSH Tunnel and Launch Xchat
"""
ssh_address = "%s:%i" % (ProxyAddress, ProxyPort)
user_string = "%s@%s" % (ProxyUser, ProxyHost)
ssh_open = subprocess.Popen(["/usr/bin/ssh", "-CND", ssh_address,
user_string], stdout=subprocess.PIPE, stdin=subprocess.PIPE)
time.sleep(1)
print ("")
print ("Kill this tunnel with Ctrl-C")
time.sleep(2)
subprocess.call("xchat")
stat = ssh_open.poll()
while stat is None:
stat = ssh_open.poll()
def main():
"""
Core Code
"""
parser = argparse.ArgumentParser()
parser.add_argument('-i', '--interface',
help="Select the interface you wish to use",
choices=['eth0', 'wlan0'],
required=True)
parser.add_argument('-p', '--port',
help="Select the internal port you wish to bind to",
required=True, type=int)
args = parser.parse_args()
proxyip = (get_net_info("%s" % args.interface))
configure_xchat_config(proxyip, args.port)
print (proxyip, args.port, proxyuser, proxyhost)
ssh_proxy(proxyip, args.port, proxyuser, proxyhost)
if __name__ == "__main__":
sys.exit(main())
Refer to the launchpad address above for more info.
Simple Python3 Code to parse your ipaddress
I’ve been doing some side projects on my own requiring me to obtain my assigned IPv4 address. In python3 you can do this by importing socket, which I believe is a better way than how I’m doing it below, however I found that using subprocess solved the issue!
I just put this together tonight and it does exactly what I wanted it to do. Feel free to copy and use it for your own little projects, you will need to add additional logic to the parser for additional network interfaces.
#!/usr/bin/env python3
import sys
import subprocess
import argparse
def get_net_info(interface):
myaddress = subprocess.getoutput("/sbin/ifconfig %s" % interface)\
.split("\n")[1].split()[1][5:]
if myaddress == "CAST":
print ("Please Confirm that your Network Device is Configured")
sys.exit()
else:
return (myaddress)
def main():
#Parser Code
parser = argparse.ArgumentParser()
parser.add_argument('-i', '--interface',
help="Select the interface you wish to use",
choices=['eth0', 'wlan0'],
required=True)
args = parser.parse_args()
# print ("%s" % args.interface)
print (get_net_info("%s" % args.interface))
if __name__ == "__main__":
sys.exit(main())
Heres the expected output below, in the event the device in question is NOT configured (unplugged/unplumbed), the following should output:
sfeole@sfmadmax:~/pythonscript$ ./sean3.py -i eth0
Please Confirm that your Network Device is Configured
And here is the expected output when the device is configured(plugged in and plumbed)
sfeole@sfmadmax:~/pythonscript$ ./sean3.py -i wlan0
192.168.1.44
And of course , invalid arguements…
sfeole@sfmadmax:~/pythonscript$ ./sean3.py -i www
usage: sean3.py [-h] -i {eth0,wlan0}
sean3.py: error: argument -i/–interface: invalid choice: ‘www’ (choose from ‘eth0’, ‘wlan0’)
Where is Windows 8 going?
So while going through my list of websites that I usually catch up on I was sent this link here regarding windows 8. I love the picture above btw, might to have to add it to my collection!
http://www.extremetech.com/computing/121015-windows-8-may-drive-me-to-linux
Now just by reading the title you would think that this is sort of a bashing the Window 8 OS itself, well quite frankly it is. It’s interesting the direction that microsoft is going. I’m not sure if everyone over there has their screws snugged tight, if you know what i mean.
May favorite pieces of this article:
Based on its current form, Windows 8 represents an unconscionable, and barely comprehensible, rejection of the values Microsoft has spent the last 26 years perfecting in its visual operating system.
And, of course, there are plenty of serious users who don’t want the PC on which they spend huge chunks of their waking life to look like it was designed by Fisher-Price.
I would have to agree with the Matthew Murray on this one, I’m really content with windows 7. In the event I want to play a game or two, i usually fire up my windows 7 box and game away. The world is not all tablets… yet??? hehe… doubtful.. but again I would like to see how this pans out for microsoft, changing their operating environment so the user experience is the same across all devices desktops / tables & phones, I think they are a little late in the game for this. By the way, who in their right mind buys a Windows phone? 🙂
Anyways doesn’t all of this sound familiar now? Ubuntu & Unity, the same desktop experience across desktops & phones & tablets, I don’t think that was announced as the original intent for switchig to Unity, but doesn’t it make sense now with the announcement of Ubuntu TV and Ubuntu on the Phone. If I remember correctly, Ubuntu took their “fair share of flack” from the community for dropping gnome but that’s a story for another post. <Let the Linux Mint Trolls come out of their caves>
Ubuntu on the Atrix2
tmpfs, speed up your day
Heres another oldie I transplanted,
Now mount that directory into memory.
#mount -t tmpfs -o size=5g tmpfs dir1
What this command is instructing the OS to do is mount the directory we just created to tmpfs. If by any chance that specific job exceeds 5GB then it will die.
It’s very important that you don’t exceed your available free memory. If so, then you will start to cache off of the disk drive. Which can cause the build to take an extremely long time to complete. So be careful!
It’s a pretty nifty trick just thought I’d post.
— L8r
echo "all_this_wizardry" > /dev/geek 