Update /etc/postfix/main.cf and add the name of your outgoing/relaying mailhost as “relayhost”. Ensure that the relay server is accepting your email first.
e.g. if the outgoing relay is mailhost.xyzserver.com sendmail configuration should look like following.
# INTERNET OR INTRANET
# The relayhost parameter specifies the default host to send mail to
# when no entry is matched in the optional transport(5) table. When
# no relayhost is given, mail is routed directly to the destination.
# On an intranet, specify the organizational domain name. If your
# internal DNS uses no MX records, specify the name of the intranet
# gateway host instead.
# In the case of SMTP, specify a domain, host, host:port, [host]:port,
# [address] or [address]:port; the form [host] turns off MX lookups.
# If you're connected via UUCP, see also the default_transport parameter.
#relayhost = $mydomain
#relayhost = [gateway.my.domain]
#relayhost = [mailserver.isp.tld]
#relayhost = uucphost
#relayhost = [an.ip.add.ress]
relayhost = mailhost.xyzserver.com
After that restart postscript.
service postscript restart
Lets say you are on a system where top is not available (or other tools similar to it). Sound incomprehensible but believe me. There are systems which do not have any of those great tools available. So how do you find the process eating up most CPU? The humble
ps command provides
pcpu which is CPU percentage used by a process. Here is how.
ps -eo pcpu,pid,ruser,args | sort -r -k1 | less
This will give in reverse sort order the “pid” that is taking up most of
pcpu and the
ruser (real user) with
args. So there you have it.
WebEx would not work on Ubuntu 12.04 64 bit with default configuration. It requires 32 bit java. WebEx control window would launch but desktop sharing, application sharing, white-board etc. do not show up. Neither I could see other people’s shared content nor I could share mine even if I am the host of the meeting.
Starting Firefox from command line on a terminal shows ELFCLASS32 error from WebEx shared objects. So it was clear that WebEx would not work on 64 bit system as is and would need 32 bit java to work. Because I use 64 bit system I do not want to downgrade to a 32 bit version just for the sake of WebEx.
In brief, these three steps cover the fix.
- Install 32 bit Oracle Java locally. Oracle Java is must and OpenJDK would not cut. Warning: because it is local installation, user would need to manually keep on updating as new java becomes available. Recently there have been many releases from Oracle which came with very little time in between addressing major security issues so this would be concerning.
- Install Firefox locally so it can be configured to use this 32 bit java. Add a different profile and use a different theme so it does not conflict with the native Firefox and clearly stands out if both are running.
- (Optional) Add shortcut in Unity HUD for quick access.
Continue reading “Setup WebEx on 64 bit Ubuntu 12.04 using 32 bit Oracle Java”
Here is how to add a custom script in Unity HUD/dash for quick access. /usr/share/applications directory has all shortcuts for Unity desktop. So create a file named “mycustomscript.desktop” (or any_name_you_like.desktop) there which has information about the custom script. Additionally an icon could be added by pointing to an image. Files in /usr/share/applications directory have to be created as root.
Comment=My Custom Script for X, Y and Z
sudo update-desktop-database after which you will be able to use Unity HUD for invoking the custom script. Also note that each time you update a .desktop file you have to run
Once a user starts a vpn client to connect to company extranet, all network traffic is diverted to the vpn tunnel. Routing gets setup by VPN client such that everything would go down the tunnel. Split tunnel can fix that by keeping traffic for internet from tunnel and only direct extranet traffic to the tunnel. But it comes with few risks on its own. Lets review the concept for a minute.
The VPN tunnel can be configured to work in two modes.
- Mandatory (default)
While a client tunnel is established in mandatory mode, all client traffic is tunneled through it by default. This is the default vpn mode. So accessing yahoo.com will go through vpn tunnel to company extranet which will then route it via its own internet connection after applying access policy etc.
- Split Tunneled mode
Split Tunneling allows configuring specific network routes that are then tunneled and sent to the client’s Extranet adapter; any other traffic goes to the local PC Ethernet or Dialup adapter interface. So Split tunneling allows the user to get access to the Internet or print locally even while the system is tunneled into the company Extranet. But this comes with a security issue because it opens a backdoor into the secure office network from internet via the home system. A hacker can exploit the home system and can use that as a jump box to get into the company network. Or if the system at home is infected it will further that infection into office network. That is why organizations want vpn users to ensure they are up to date and have anti-virus installed and most will provide vpn clients that are tightly controlled to enable the Default mode. Continue reading “vpn : Split Tunnel Concept”
/etc/udev/rules.d/70-persistent-net.rules defines the names for network interfaces. You can modify it, as long as you keep each rule on a single line, and change only the value of the NAME= key (as per the file). Continue reading “Rename network interface on ubuntu”
If you are getting following error in xming log:
Xming.exe: client 4 rejected from IP XXX.XXX.XXX.XXX
Here are two solutions.
- Secure method: Edit: X0.hosts (in the installation directory) and add the ip you want allow. e.g.
- Insecure method: Add the “-ac” option to the Xming desktop shortcut. Modify the Desktop Xming shortcut to include the arguments: “:0 -clipboard -multiwindow -ac”. The ac option accepts client requests and quells the error above. Start Xming using the shortcut you just created. Warning: This is same as “xhost +” which will grant anyone access. So only use Xming option -ac or “xhost +” on trusted networks, never on public ones. OR use the solution 1 of additing IP address of known systems on which you will be running X applications..
I moved to Ubuntu full-time a while back. See the first part Migrating from Windows to Linux. But VPN into my office from Linux remained an open issue because my organization uses Nortel Contivity. Ubuntu comes with vpn client but that does not work with Nortel. Then I found vpnc-nortel branch of vpnc open source project that can connect to Nortel vpn servers. In this series I will explain how to connect to Nortel VPN from Ubuntu. You may need to tweak few of these instructions for your favourite Linux version. I am on Ubuntu 11.10 x86_64, using vpnc version 0.5.3-481.
Continue reading “VPN : Connecting to Nortel VPN from Linux”
What would one need to move off of Windows in corporate world? A replacement for Microsoft Office Suit. Linux has LibreOffice as replacement for MS Word, Excel, Power Point etc. If you are a power user of these tools then it will be difficult to migrate to LibreOffice but hey that is a start. If for Outlook, your organization provides access via WebMail interface, then you are in clear with using any email client on Linux that supports Pop or IMAP by making use of DavMail. Though Evolution support a direct access to WebMail or even MAPI, but Evolution itself is very thick and sometimes slow. Then came out Ubuntu 11.10 which provides Thunderbird as the default email client with integration to desktop and Unity. Perfect.
Here is the list of replacements that are available on Linux. I will cover setup for DavMail and Thunderbird in another post. Continue reading “Migrating from Windows to Linux”
Syntax for grep to search for a pattern in a file is very well-known. But there are times when one has to grep for the pattern from a certain location or after a certain offset in the file. For example if we are searching for a pattern in a log file which could appear multiple times. Each time we grep, it will provide us all the matching lines from top to bottom of the file and then we have to find which lines were new since our last run. Using dd, the file can be sliced and then grep can be applied for the pattern on that slice. Lets see an example. Continue reading “bash : grep for pattern from certain location in the file”