Blog News Continued

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Blog News – Continued

I apologize for the apparent lack of new content, however be rest assured that I have not been sitting idle.   The theme upgrade from Aspen to Weaver went well,  I have noticed no issues with the blog at all!  I have purchased the Pro version of multi-rating which will allow me to create multiple rating forms for different type of posts.  This will eliminate a posts rating being negatively affecting by having rating questions that do not apply to the post topic.  Such as being asked if an article on mounting a Windows SMB share to CentOS Linux would entice you to visit Korea ( I know if I was sitting on the fence, that article would totally entice me to visit! ).

Mi Jung and I are packing to return to Yeongwol for the long weekend, so you can be expecting another great trip report in the coming month.  I am hard at work on another great technical article, and constantly working to bring more great and informative content to the site!

Please be patient as that great content is coming!

To all that continue to visit the site, thanks for your support!

Brent P Hendricks

Brent’s world Blog and forum administrator

Brent’s World Blog News – Weaver Xtreme (Theme) Installed

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Blog Update

Weaver Xtreme Theme Installed

As stated in our 2016 blog goals, I have completed testing and installation of the Weaver Xtreme.  The decision was made to upgrade as our long time used theme Aspen was no longer being updated.  Weaver Xtreme was created by the same author, and Brent’s World could retain the look and feel that you are familiar with!

We will be testing the new theme in production for 30 days before purchasing a single site license.  Any feedback on the new theme would be appreciated.  Especially if you encounter any issues, or notice reduced performance.

You will also notice that I am using a new banner picture, as it had not been updated since 2015!  I will be working for a more permanent banner picture in the next couple of months!

I hope you like the new theme, and will keep returning for great articles from Brent’s World!

Wednesday Quickie – Outlook 2016 Attachment Reminder

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Wednesday Quickie – Outlook 2016 Attachment Reminder 

I accidently discovered a new feature in Outlook 2016 the other evening that I thought I would share.   I know we have all done this at work, I know I am guilty of this quite often.  In the process of sending an email that is supposed to contain an attachment, we become so focused on the content of the email that we forget the attachment when everything is said and done.

Depending on the content, this can either be embarrassing, or if you were sending your resume for that perfect employment opportunity, catastrophic!

So I was quite surprised this evening when I was helping someone troubleshoot an issue with an Amiga startup script, and was doing a poor mans attachment (Copy and Past) into the email text, when I hit Send, I received a message stating ,” You may have forgotten to attach a file.  (Don’t Send), (Send Anyway)”.

Forgotten_Attachment

I do not know if I should be scared, as my apps now actually seem to be reading my email while I type them, or delighted over this potentially life saving feature.   On the paranoid side it kind of brings back memories of this Clippy meme.

Clippy-Suicide Note

 

 

Anyway,  it has been awhile since I have posted a Wednesday Quickie, and was so pleased to stumble upon this feature, that I just thought I would share!

 

 

 

 

Thanks for visiting Brent’s World, and I hope you check out our other great article
Also be sure to check out and participate in our forums, at www.catracing.org/hendrb/forum.

Brent P Hendricks (Blog and forum administrator)

 

Post Update – Active Directory Authentication Fixed in SAMBA Update 4.2.10-6.2.el7_2

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Blog - CentosIt was back in April when I posted the article here that SAMBA Update 4.2.10-6.el7_2 completely broke authentication with a Windows Active Directory domain controller, and in an emergency had to roll back to the previous version.   That blog post can be found here.  http://4.2.10-6.2.el7_2. It has been one of the most popular posts the last couple of months.

The update was released to fix the Badlock vulnerability, which could leave your servers open to man in the middle, or denial of service attacks.  The only problem was, that upon installation and restarting of the SAMBA services, domain users were unable to authenticate with their accounts.  After a few hours of trying to troubleshoot the issue, the only option available was to roll back to the previous version of SAMBA.  Not something to be taken lightly especially when a vulnerability patch is involved.

Surprisingly it took 2 months for the next SAMBA update to be released in the CentOS Repos.  I hear that Ubuntu had a fixed version almost immediately.  Something to think about when I think about putting my next Linux server online.  In fact with the version number being so similar I almost missed it, except I was actually physically looking at the REPO directories on a CentOS mirror and noticed the June 25th modified date.

I immediately fired up my development server, and did a YUM UPDATE, this is what was waiting for me.

samba                  x86_64        4.2.10-6.2.el7_2      updates          615 k
samba-client        x86_64        4.2.10-6.2.el7_2       updates          497 k
samba-client ibs  x86_64         4.2.10-6.2.el7_2       updates         4.3 M
samba-common  noarch          4.2.10-6.2.el7_2       updates         273 k
samba-common-libs  x86_64  4.2.10-6.2.el7_2       updates          157 k
samba-common-tools  x86_64 4.2.10-6.2.el7_2      updates          445 k
samba-libs                   x86_64 4.2.10-6.2.el7_2      updates          261 k
samba-winbind            x86_64 4.2.10-6.2.el7_2      updates          466 k
samba-winbind-clients x86_64 .2.10-6.2.el7_2       updates          120 k
samba-winbind-modules x86_64 4.2.10-6.2.el7_2  updates          106 k

After the update I rebooted the server (The update included a kernel patch), and did a simple wbinfo -u (Windbind list users)  I was happily rewarded with a list of my domain users!  The final test was switching to a domain user account with SU – (domainusername).  Again I was happily rewarded with a successful login.

On one hand I can happily say this issue has been fixed, but it does leave me with a somewhat bad taste in my mouth that it took this long to get a fix into the repository, when the same issue was affecting Ubuntu’s users and the patch was made available within weeks.  I understand the philosophy behind CentOS and it’s stability.  However leaving your users with a known vulnerability for months seems like a poor choice!

Anyway,  I am happy to report the issue as being resolved!, and I thank the people who came to Brent’s World after I reported the problem!

Be sure to register on our forums and join in our technical discussions.
www.catracing.org/forum

 

 

Greek Food in Korea II – Greek Joy

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Greek Restaurant In Seoul – Greek Joy

 

Greek Joy - BadgeI usually do not write the same type of articles back to back, but I wanted do a comparison piece to the article I wrote last week on our dining experience at Santorini’s in Itaewon.  We enjoyed the Greek food so much I decided to try one of the other restaurants in Seoul.

We decided  to try Greek Joy which is located in the Mapo / Hongdae area of Seoul.  It looked really easy to find, and was located right off subway line #6, so we would not even have to transfer.

There was some confusion because the address that I found on Tripadvisor showed us to still be 17 minutes away on foot while exiting the station, while Mi Jung was pretty sure it was located behind the Holly’s Coffee building outside the station.  A quick phone call proved Mi Mung correct, and we were easily able to locate the restaurant.

I ordered the Gyro sandwiches with Salad.  If you do not want to order the salad, you can get the sandwiches al la carte, but the salad was only a couple thousand won extra (about $1.85).

Greek Joy - Gyros + Salad

The salad came with a basket of some really soft and delicious sweet bread, which is eaten with balsamic vinegar in olive oil.  The salad was good, but the dressing used a little too much vinegar, both Mi Jung and I agreed on this.

Here are the Gyro sandwiches, they were a good size, and very flavorful, Now we will have to go back to Santori’s so I have something to compare.

Greek Joy - Gyros plate

Mi Jung ordered the Lamb steak  from the set menu, the set included the lamb chop pictured here, rice, and a stuffed tomato.  Mi jung though the dish was excellent, and would order it again.

Greek Joy - Lamb Steak w stuffed tomatoe

I personally preferred the food at Santorini’s,  I felt like the portions were bigger, and had a little more flavor..  The food was good, and the staff friendly.  We got to speak to the owner on the way out, and were asked to sign their birthday register,  were the restaurant will send you a birthday gift during your birthday month.  I would definitely recommend giving the restaurant a try.  For lunch or dinner.

Here is a sample of their dinner menu.

Greek Joy - Menu

Restaurant Contact Details:

Address: 121-837  14, Wausan-ro 21-gil, Mapo-gu, Seoul
Phone # +82-2-338-2100
Business Hours: Monday – Sat 11:30am – 11:00pm

How to get there: Take Line 6 or Line 2 to Hapjeong station, Exit #7. Go around Holly’s Coffee on the left hand side, You will see the sign for Greek Joy. It is located on the second floor.

** If you enjoy visiting Brent’s World and wish to be notified when a new article is posted, please registered. This can be done easily by going to www.catracing.org/hendrb/login.php

*** We also offer a full featured forum at www.catracing.org/hendrb/forum. This allows you to start or join in discussions about Korea, or other technical topics. Please stop by and join in a conversation.

 

 

 

Greek Food In Korea – Santorini

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Santori Title
Greek Food In Itaewon – A night at Santorini’s

 

 

We have found and reviewed all kinds of foreign food in Korea.  From American to Chinese, Japanese Korean fusion, and even Mexican.  I was feeling like I wanted to try something different and after some hankering with Mi Jung finally decided to try some Greek food.  Mostly because I was dying to get a hold of some stuffed grape leaves.  So off I went scouring the depths of Google.

Santorini’s stood out  on Trip Advisor and several other food blogs, and while I was not looking forward to feeling like I was duplicating others reviews, I was hungry, and feeling lazy.  So off we went on the Yongsan 3 bus, to the Ministry of National Defense stop, and transferred to the blue 110B bus which dropped us off directly across the street from the Hamilton Hotel.

\The hardest part about getting directions from other food blogs is they don’t always give you a starting reference point.  I knew it was behind the Hamilton Hotel, and past Holy Chow.  To me that meant go right, leaving the restaurant on our left.  MI Jung with a better sense of directions felt we needed to go to the left towards the old 3 Alley Pub.  Mi Jung turned out to be correct and we found the restaurant located upstairs on the 2nd Floor.

The restaurant was more spacious then I expected, and we got a nice table by the window, so we could see Itaewon proper from where we were.   Water was brought to the table in a wine bottle, and we lost no time perusing the menu.

I choose these cheese filled turnovers called  Tiropitakia served with tzatziki.

Tiropitakia

Mi Jung ordered the following Muscle platter.

Muscle platter Mi jung eating muscles
For the main course, I chose the pork gyro plate. The plate came with plenty of pork Gyro, but not enough pita bread.  You could order more pita bread for an additional 3,000w, but I just ended up eating the meat by itself.

Gyro
The meal was flavorful, filling, and cost a very reasonable 55,000w, we also got free  desert brownies afterwards.  We will definitely be going back and trying out more items on the menu,  We also both need to try the Baklava for desert.   We will now also have to find another Greek restaurant to compare Santorini’s to, so be looking for another review in a couple of months.  If you are in the mood for Greek food, or just want to try something different, I would definitely give Santorini’s a try!

How to get there.

SUBWAY – Take line 6 to Itaewon Station, Way Out Number 1.

BUS.  From Samgakji station take bus 110B, get off at the Hamilton Hotel stop and cross street.

Walk past KFC, and make a right into the alley.  Upon reaching the cross street make a left, Look for Santorini’s on your Left, and go up the stairs to the second floor.

CentOS 7 – Resetting Lost Root Password

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CentOS 7 – Resetting Lost Root PasswordBlog - Centos

You have just discovered that you have forgotten the root password of your CentOS 7 workstation or server.  What are you going to do?

 

 

If you have access to an account that is a member of the group ‘wheel’, you only need to login with that account and type the following at the shell prompt

$sudo passwd root

[sudo] password for (username) : **********

Changing password for user root.
New password: (Enter New Password)
Retype new password: (Retype New Password)
If you entered and confirmed the password correctly, the shell will return the following, and return you to the shell prompt. For Example.

passwd: all authentication tokens updated successfully.
$

Now we can try switching user to the root account with the new password.

$ su –

NOTE: The switch user ‘su’ command defaults to the account root unless another account is specified. The ‘-‘ option tells the switch user command to load the accounts environment variables.

You then should be prompted with the password prompt, and if the change performed above was successful you should be logged in.

$ su –
Password: *******
Last login: Sun May 29 10:43:00 KST 2016 on tty1

“Wish I had a decent book of quotes!”

-Sysop

#

Notice the shell prompt is now a #, this indicates you are using the root account.

So what if you do not have an account that is a member of the group ‘wheels’?
You will need to boot your system into single user mode.

Here is where it gets rather sticky, as you do not have access to the root account, you will be unable to gracefully shut your server down (unless there is an account that has been given access to the reboot, or shutdown command through the sudoers file), if you run applications on this server that have a database backend like MySQL or MariaBD there is a possibility that data corruption will occur! Proceed at your own risk.

Physically reboot your Centos box.

From the grub bootloader, enter ‘e’ for edit

Grub

 

On the next screen use your cursor keys, and cursor down until you see an entry starting with ‘linux16’, we will be making the following changed on this line. NOTE using your cursor keys, move the cursor keys with your UP / DOWN cursor keys to the beginning of the block of text and use your left cursor key to position the cursor at the end of ‘ro’

Section after edit

Change ‘ro’ to ‘rw init=/sysroot/bin/sh’

NOTE: DO NO COPY THE SINGLE QUOTES. (See screen shots!)

The grub screen should now look like this. (NOTE: What looks like an underscore between init=/sysroot/bin/sh and rd.lvm.kv…. is actually your cursor. There should just be a space here.

Section before edit
Now press ‘Ctrl-x’ to exit and boot into single user mode.

Once you are in single user mode, issue the chroot command as follows.

:/# chroot /sysroot

We can then issue the passwd command to change the root password.

:/# passwd root

Your screen will look like this.

Single User Mode Password Change

 

Now update selinux

:/# touch /.autorelabel

Now exit chroot

:/# exit

Finally reboot the system, and test logging in a root.

:/# reboot

This brings up a good point, with it being this easy to change the root password, isn’t this a possible security issue, and if so what can be done to harden the system and prevent someone from coming along, rebooting our Linux machine and changing the root password?  The answer to this question is YES!  This is a big security hole and there are several things that can and should be done to prevent this sort of attack.

  • Set a grub bootloader password.
  • Enable root password for single user mode.
  • Enable root password for recovery mode.

Performing options 2 and 3, will require you to boot from the CentOS live CD in order to reset a lost root password, and can be circumvented if password is required to access the system BIOS. We will go over these 3 options in next month’s Brent’s World technical blog.

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Thanks for reading, and have a great day!

Korean Movie Review – Ajusshi (The Man From Nowhere)

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Korean Movie – Adjusshi (The Man From Nowhere)

The Man From NoWhere In Hangul (Korean), Adjusshi means mister, or older man, in the case of the Korean action thriller of the same name it describes Cha Tae-sik perfectly.  A lonely pawn shop owner, he does not get close to anyone except the daughter of a neighbor named So-mi. Which is where the Korean version of this film get’s his name, because the man never tells So-Mi his real name, so she is left to call him ,“Mister” Who befriends him to temporarily escape the brutal world of her mother.  Who is a prostitute, dancer, and heroin addict.  After So-mi’s mother Hyo Jeong steals a package of drugs from her employer, she gives a camera bag to Chat Tae-sik without his knowledge for safe keeping.  Under torture Hyo Jeong reveals where the drugs are and is then kidnapped along with So-mi.

Cha Tae-sik is then assaulted and left for dead, and must try and find out who his assailants are and attempt to rescue So-mi and Hyo Jeong.   Complicating matters, the police also want to question Cha Tae-Sik in the disappearance of his neighbors.  The police as shocked to discover that they have no records that he ever existed.  Who is “The Man From Nowhere” and were did he come from?

The movie takes on twists and turns until the shocking and climatic ending.

I really enjoyed the film, the story, acting, and fight scenes were top notch!  This is definitely a rollercoaster of a thriller, with enough plot twists to keep you entertained throughout the movie.  The only drawback was the only version that I could find was the English overdubbed version released in the United States.  If you can, I would definitely find a version that you can watch with the original Korean language track and English subtitles.  I find the overdubbed voices to be extremely flat, and not carrying the emotions of the original actors, which definitely takes away from the film and almost adds a comedic element to a film that really is not supposed to have one.

This is definitely a foreign action film I highly recommend!  Though I will warn you there is quite a bit of violence, not as much as Old Boy, but definitely more visceral fight scenes then you may be used to from some of the Chinese Martial Arts faire.  The movie can be rented from the iTunes Music Store, or Amazon Video.  The DVD or Blu-Ray can also be purchased from Amazon.

LINUX Alert! – SAMBA update 4.2.10-6.el7 Breaks Active Directory Authentication.

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Active Directory Authentication Breaks After Installing SAMBA 4.2.10-6.el7_2

This Issue Has Been Resolved! See Post – https://www.catracing.org/hendrb/post-update-active-directory-authentication-fixed-samba-update-4-2-10-6-2-el7_2/ For additional information!

This is not going to be a very long technical post, but I did want to get the word out that the latest update to the SAMBA client broke Active Directory authentication on my web server, and how to fix the issue.

While applying Windows Update fixes to my Windows servers, I also checked for updates on my CENT-OS box, and lo and behold there were quite a bit of updates, one being another SAMBA update. I can not remember a time where a package update broke something on my production box, the only other times I have had serious issue is after installing kernel updates.  So needless to say I was quite shocked after rebooting the server (Runs as a virtual machine on top of the Windows box that had rebootable updates installed).  I could no longer login with my AD account.  NOT GOOD!  Fortunately checking to make sure I can login as root and my local account is part of my pre-update checks.

Packages

After the updates and a reboot of the server you can see it is not allowing me to login with my domain account.

Login Failed
Here are the error message logged in /var/log/secure
(Server hostname has been replaced with ****)

Apr 14 13:50:53 **** polkitd[804]: Registered Authentication Agent for unix-session:c1 (system bus name :1.28 [gnome-shell --mode=gdm], object path /org/freedesktop/PolicyKit1/AuthenticationAgent, locale en_US.UTF-8)

Apr 14 13:51:33 **** gdm-password]: pam_unix(gdm-password:auth): check pass; user unknown

Apr 14 13:51:33 **** gdm-password]: pam_unix(gdm-password:auth): authentication failure; logname= uid=0 euid=0 tty= ruser= rhost=

I promptly removed the updated version of SAMBA and reinstalled the previous version. I always take a screen capture of the what yum is going to update before answering yes.  This makes an easy reference in case I need to go back and remove anything.  In this case I need to remove the following packages.

 samba                                 x86_64   4.2.10-6.el7_2                               updates   614 k
 samba-client                       x86_64   4.2.10-6.el7_2                               updates   496k
 samba-client-libs                 x86_64   4.2.10-6.el7_2                               updates   4.3 M    
 samba-common                  noarch   4.2.10-6.el7_2                                updates   272 k
 samba-common-libs            x86_64   4.2.10-6.el7_2                              updates   156 k
 samba-common-tools          x86_64   4.2.10-6.el7_2                              updates   444 k
 samba-libs                           x86_64   4.2.10-6.el7_2                               updates   260 k
 samba-winbind                    x86_64   4.2.10-6.el7_2                               updates   465 k
 samba-winbind-modules      x86_64  4.2.10-6.el7_2                               updates   105 k

$ yum remove samba samba-client samb-client-libs samba-common samba-common-libs samba-common-tools samba-libs samba-winbind samba-winbind-modules

Once samba, and samba-winbind have been uninstalled, we need to install the previous version, again the listing I keep of all updates installed on the server come in handy, as I know SAMBA was updated back in January.

samba-client             x86_64     4.2.3-11.el7_2          updates     496 k
samba-client-libs       x86_64     4.2.3-11.el7_2          updates     4.3 M
samba-common        noarch     4.2.3-11.el7_2           updates     269 k
samba-common-libs  x86_64     4.2.3-11.el7_2          updates     156 k
samba-common-tools x86_64    4.2.3-11.el7_2          updates     443 k
samba-libs                  x86_64     4.2.3-11.el7_2          updates     259 k
samba-winbind           x86_64     4.2.3-11.el7_2          updates     463 k
samba-winbind-modules x86_64 4.2.3-11.el7_2         updates     104 k

First let’s get the package names for all available versions of samba

$ yum –showduplicates list samba

Available samba

The update we want 4.2.3-11.el7-2 is available. So let’s go ahead and install them.

$ yum install samba-0:4.2.3-11.el7_2.x86_64

Once the samba client is installed we need to install samba-winbind

$ yum install samba_winbind-0:4.2.3-11.el7_2.x86_64

Once this was complete, I rebooted the server, but was still unable to connect to the domain controller. Comparing files on my development server, I noticed that the /etc/samba/smb.conf file was modified on the server during the removal of the samba package.  Not to worry yum made a backup first.

files

So let’s remove the new smb.conf

$ rm smb.conf

Now let’s rename the smb.conf.rpmsave to smb.conf

$ mv smb.conf.rpmsave smb.conf

Now let’s go ahead and reboot (You don’t need to, you can just shutdown your networking and samba service.), but a reboot never hurts.

$ reboot

Test logging in with a domain account, if the login still fails, log back in as your local account and troubleshoot the AD connection.

  1. Is the time on the LINUX box within 5 minutes of the time on the Active Directory server? If no this will cause the Kerberos ticket issuance to fail
  2. Can you issue wbinfo commands.IE wbinfo -g or wbinfo -u. If not, you may have to rejoin the domain.

These instructions should repair your domain authentication until the issue with the new version of SAMBA is resolved. I will keep working on a fix, unless another update fixes the problem.

NOTE: If you know the fix for this issue with SAMBA update, please either shoot me an email, or post it to our forums or as a comment.  You will get full credit for providing the fix.

Quickie – What to expect in 2016

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Brent’s World Quickie – What to expect in 2016

I know it seems like things have been a bit slow here at Brent’s World Lately, I have been dealing with an injury in the family and have not had time to go out and get some of the great content you expect. Hopefully now that the weather has warmed up, I will be able to get out more.

Here are some changes / upgrades to expect in 2016.

New Theme – I am looking to migrate to a new theme for the blog, the current theme Aspen is no longer being updated by the author, so I am looking to migrate to his new theme Weaver Extreme. This is an ongoing project, as I am working on building a test server to migrate the blog to, and test and modify the theme before placing it into production. This will minimize downtime, and make sure you, the followers of my blog do not have any unexpected surprises.

Category Scrub and indexing – I will be scrubbing un-unused categories and only keeping the blog categories that are used, such as Korea, Travel, Movie Review, Restaurant Review, and Technical. I will be implementing an indexing scheme so each category will have its own page, so you can easily find the articles you are interested in!

Please be patient as we get back up to speed and continue to bring you great content!