Archive for the ‘comp’ Category

Tayga, stateless NAT64 implementation

Monday, January 25th, 2016

If you are planning for an IPv6 only Data Center (and if you plan for the future, you are doing that) you may have noticed that there are applications out there that are just not ready for IPv6 yet. So you need some kind of 6-4 translation, either locally or in the network. From the Tayga wash label:

TAYGA is an out-of-kernel stateless NAT64 implementation for Linux that uses the TUN driver to exchange IPv4 and IPv6 packets with the kernel. It is intended to provide production-quality NAT64 service for networks where dedicated NAT64 hardware would be overkill.

Tayga is production quality software. We use it for ipv4 access for large amounts of production nodes every day. It is for example well suited for giving 6-to-4 network access for docker nodes. You may find more information about Tayga on it’s homepage: http://www.litech.org/tayga/

I pushed tayga-0.9.2-3 to Fedora 22 and 23 stable today. It will trickle down to your local mirrors in a couple of days. I have also forked tayga for epel5, epel6, and epel7. Please contribute by testing tayga for EPEL: https://bodhi.fedoraproject.org/updates/?packages=tayga

Update: tayga is now available in EPEL

Redpill Linpro is the market leader for professional Open Source and Free Software solutions in the Nordics, though we have customers from all over. For professional managed services, all the way from small web apps, to massive IPv4/IPv6 multi data center media hosting, and everything through container solutions, in-house, cloud, and data center, contact us at www.redpill-linpro.com.

J.R.R. Tolkien: The Hobbit, TBOFA extended ed.

Wednesday, December 23rd, 2015

I read J.R.R. Tolkien’s “canon”, that is, The Hobbit, The Lord of the Rings, and the Silmarillion, every Christmas. So also this year.

Not much to post about The Hobbit this year, except that I also watched the extended edition of The Battle of the Five Armies some time ago. And I enjoyed it.

There are things to say about Peter Jackson’s Hobbit project, and I’ve actually already said a bit about the theater version. The extended edition, in plain 2D on a decent TV screen is a better film. There are things to dislike. How come Galadriel is the most powerful of the White Counsil? (Or is she?) The bunny sleigh is always annoying, and Legolas running up falling rocks is still a bit too disneyish for my taste. But hey, we also got more Beorn, more Esgaroth, and more Dale. That counterweights a lot. But what gave me most in this version, compared to the theater one, is the feeling of closure. We get Thorin, Fili and Kili’s funeral. Thorin has the Arkenstone on his breast, and Daín is crowned king. This is very satisfactory, and was reason enough for me to watch the movie.

Of Balin and Thrór’s Ring (J.R.R Tolkien: The Lord of the Rings)

Wednesday, December 23rd, 2015

I read Tolkien’s canon (The Silmarillion, The Hobbit, The Lord of the Rings) every year about christmas. This year’s pondering is over Balin and Gandalf and Thrór’s ring.

Thrór possessed one of the seven rings that the dwarves got from Sauron of old. Inherited from father to son through generations, it was an heirloom of immense value for the Durin line. It passed to Thrain, who was Thrór’s son, and Thorin Oakenshield’s father. When Sauron woke again during the Third Age, Thrain was taken captive in Dol Guldur, and the ring taken from him. He perished there before Gandalf could resuce him. All this Gandalf told in the council of Elrond.

Now, by the same council, Glóin reveals that one of Balin’s main reasons for attempting to recolonize Moria, was to find Thrór’s ring. But Gandalf knew that it was not in Moria, as it was taken from Thrain in Dol Guldur. When Gandalf knew this, it is quite obvious that Thorin knew too. Gandalf would not keep information hidden about Thrain’s condition and death from his only son. So both Gandalf and Thorin must have known that Thrór’s ring was taken. Still, Balin, did not know, even though he was a close friend and companion of both Thorin and Gandalf. Consider the last scene in the Hobbit, where Gandalf and Balin, on a journey all the way from The Lonely Mountain, visit Bilbo. It is a meeting between close friends. Yet, Balin knew not. So he went with his followers to seek for the ring, and the whole colony was killed cruelly, fighting a last stand against the orcs of Moria.

In retrospect, a bit more openess about the ring would perhaps have been advisable. But the keeping and the keeper of the ring was constantly kept a tight secret in the Durin line. No one knew for sure who had the ring, until it was given to its next keeper. The appendices tell us that the dwarven rings were treacherous. Though not making the dwarves into shadows and slaves of Sauron, the ring keepers of the dwarves became jealous, and a constant hunger for more gold was set in them. Thus, the ring was often the base for a large hoard of treasure, which in turn could cause grieves like wars and dragon plunder.

Perhaps Gandalf considered this, when he kept his knowledge about Thrór’s ring hidden. It is still a bit of a mystery to me though.

Poor man’s VPN via ssh socks proxy

Sunday, December 13th, 2015

This was also posted on Redpill Linpro’s Sysadvent blog

It is late night. You have just arrived at your Grandparents, when the SMS beeper goes off. There is a problem with a SAN controller, and the on-call person know you fixed it the last time. Now, if you only had documented it.

You know you have to fix this yourself, but you have no VPN access. You don’t even have an Internet connection, except your 3G mobile phone, and you really need access to that admin web gui. There is an emergency ssh port available, but no other port is open. X-forwarding over 3G? Not an option. ssh port-forwarding and fix /etc/hosts. Doable perhaps? VNC over ssh? Awkward. Enter the ssh socks proxy!

Emergency web access

Simply run:

$ ssh -D 1080 login.example.com

Now, you have a local port 1080 that creates a SOCKS proxy to the server side. Firefox has support for that proxy.

Settings -> Advanced -> Network -> Configure how Firefox connects to the Internet -> Manual settings, Socks: localhost, Port: 1080

If you need to resolve addresses from the server side, add that to the config. In the URL field, type about:config , then search for key

network.proxy.socks_remote_dns

Set it to true. That is all. You are now surfing as if Firefox was running locally on the login server. Remember to reset your settings after you have finished your session, or Firefox will not work properly when you close your SOCKS proxy ssh shell.

Not just surfing

But wait, there’s more. With a local SOCKS proxy, you may also use other programs, and they don’t even have to support SOCKS themselves. Install tsocks, and set localhost as the socks proxy host:

$ sudo yum install tsocks || sudo apt-get install tsocks
$ echo "server = 127.0.0.1" | sudo tee /etc/tsocks.conf

tsocks is a little gem of a program. It hooks into other programs, and redirects network traffic to the local SOCKS proxy. Now, while the ssh SOCKS proxy is still running (the ssh -D1080 command), just use tsocks to run your favourite program through the proxy:

# Log into a server on a closed network behind the firewall
$ tsocks ssh server.behind.firewall.example.com
# Run a local psql shell against a remote server through the SOCKS proxy
$ tsocks psql -U pg_admin_user -W -h database.behind.firewall.example.com -W template1

or to run a whole session of commands through the socks proxy, start with “. tsocks on” (note the leading dot), and stop it with “. tsocks off”

$. tsocks on
$ command
$ command
$ command 
$. tsocks off

To run Firefox through the SOCKS proxy, but without changing its configuration:

$ tsocks firefox http://ripe.net   # Stop firefox first

To check tsocks status, run

$ tsocks show

If the LD_PRELOAD variable is empty, tsocks is disabled for this shell.

Note that all Internet traffic is not routed via tsocks. For example, ICMP is not.

Bash process substitution

Saturday, December 12th, 2015

Also posted on Redpill Linpro’s sysadvent blog

In bash, we often use redirects (that is < and > ) to get output from a command to a file, or input from a file to a command. But sometimes, commands takes two or more files as input. Then our ordinary scheme does not work anymore.

Let’s say you want to diff(1) the output of two commands. For example, compare the contents of two directories. You may run the two commands, and redirect the output to files, then diff the files, and finally remove the files. Awkward.

 $ ls dir1 | sort > file1
 $ ls dir2 | sort > file2
 $ diff -u file1 file2
 $ rm file1 file2

Since diff can take stdin as one input via the special filename ‘-‘, we might cut down to one file, but this is still awkward.

 $ ls dir1 | sort > file1
 $ ls dir2 | sort | diff -u file1 -
 $ rm file1

Bash has (of course) a better solution: Process Substition, that is, treat the output (or input) of commands as files. Enter the process substitution operators:

 >(command list) # Input
 <(command list) # Output

Now, let us solve our diff challenge with a simple oneliner:

 $ diff -u <( ls dir1 | sort)  <( ls dir2 | sort )

Neat, isn’t it? I use this all the time!

Bonus: Avoid subshell scripting

The following bash shell loop is a pitfall often missed, leading to subtle bugs that are hard to spot. Pipe to a while loop runs in a subshell, so global variables goes out of scope when they are changed inside the loop.

 #!/bin/bash
 global=0

echo "Outside loop, global=$global"

 for n in 1 2 3; do echo $n; done | \
 while read i; do
     global=$i
     echo "Inside loop: global=$global"
 done
 
 echo "Outside loop, global=$global again :-("

Using command substitution, we avoid this elegantly:

 #!/bin/bash
 global=0
 
 echo "Outside loop, global=$global"
 
 while read i; do
     global=$i
     echo "Inside loop: global=$global"
 done < <( for n in 1 2 3; do echo $n; done )
 
 echo "Outside loop, global=$global still :-)"

Varnish-4.1.0 released, packages for fedora and epel

Monday, October 12th, 2015

Varnish-4.1.0 was recently released, and as usual, I have patched and wrapped up packages for fedora and epel. As 4.1.0 is not api/abi compatible with varnish-4.0, packages for stable releases of epel and fedora are not updated. Varnish-4.1.x will be available in a stable Fedora at latest from f24, though the package recompiles fine on anything from el5 to f23 as well.

Prebuilt packages for epel5, epel6, and epel7 are available here: http://users.linpro.no/ingvar/varnish/4.1.0/.

If you are a fedora contributor, please test the f23 package. The package should install directly on el7 and all supported fedoras, including f23. Then report feedback and add karma points. With a little luck, varnish-4.1 will go into fedora 23 before it freezes.

Ingvar

Varnish Cache is a powerful and feature rich front side web cache. It is also very fast, and that is, fast as in powered by The Dark Side of the Force. On steroids. And it is Free Software.

Redpill Linpro is the market leader for professional Open Source and Free Software solutions in the Nordics, though we have customers from all over. For professional managed services, all the way from small web apps, to massive IPv4/IPv6 multi data center media hosting, and everything through container solutions, in-house, cloud, and data center, contact us at www.redpill-linpro.com.

The Letters of J.R.R. Tolkien

Saturday, September 19th, 2015

How did we communicate before email? Before SMS? Before faxes? While using a telephone was an expensive luxury? People wrote letters. Writing a personal letter is a great exercise for the mind, giving the opportunity to think and focus, and make visible the train of your thought. Those who loved their language probably wrote more than others. And for many it was customary to keep letters, for reference, or for cherishing. So while looking for clues about someone’s life over the first 70 years of the 20th century, one should look for their letters.

J.R.R. Tolkien had during his lifetime a massive correspondence. He constantly wrote to his family, employers, friends, and publishers. Some of them are collected in this book. Through his letters, we follow his life, as seen with Tolkien’s own eyes, from the small everyday events when writing to his friends and family, through the drafts of The Lord of the Rings while writing to his publishers, and even to religious musings or pure philosophy, when writing to his children in his elder days.

Many of the letters were found in draft form, or collected from their receivers. The collection is comprehensive, but of course not complete. Lots of letters are missing, and no one knows how many Tolkien ever wrote. From the known letters, this is of course also an edition, and the editors have focused on Tolkien’s life, and especially the occations that touched the legendarium, from which his most famous works arose.

For those interested in Tolkien’s life and the story of his books, this is pure silver, and specked with golden treasures, like these:

Got my head-harvest reaped: a big crop: still fertile soil, evidently (#63)

The vast sum om human courage is stupendous (#64)

Finnish nearly ruined my Hon. Mods, and was the original gem of the Silmarillion (#75)

I coined the word ‘eucatastrophe’: the sudden happy turn in a story which pierces you with a joy that brings tears (which I argue is the highest function of fairy-stories to produce) (#89)

This university business of earning one’s living by teaching, delivering philological lectures, and daily attendance at ‘boards’ and other talk-meetings, interferes sadly with serious work. (#117)

The Letters of J.R.R. Tolkien is highly recommended reading. And if you get nothing else from this, at least I have learned, that taking time to write personal letters, is something I should do more often.

jemalloc-4.0.x for fedora and epel

Thursday, August 20th, 2015

jemalloc, Jason Evans’ general-purpose scalable concurrent malloc implementation, was recently updated to version 4.0.0. I have wrapped packages for Fedora, and will update rawhide in a few days. If you would like to test the packages already, have a look at http://users.linpro.no/ingvar/jemalloc/4.0.0/.

Update: Jason recently released updates through 4.0.1 to 4.0.3. Packages for 4.0.3 are pushed to rawhide. Builds for epel are available at http://users.linpro.no/ingvar/jemalloc/4.0.3/.

There are a few fedora packages that rely on jemalloc. If you have a chance to help testing, please recompile and test the package against the updated version. You can leave comments here, or send me a mail.

$ sudo repoquery --whatrequires jemalloc |\
  sed 's,\(.*\)-.*-.*,\1,g;' | sort | uniq | tr '\n' ' ' | fold -s; echo

blender blenderplayer bro gridengine gridengine-execd gridengine-qmaster 
gridengine-qmon jemalloc-devel nfs-ganesha nfs-ganesha-ceph nfs-ganesha-gluster 
nfs-ganesha-proxy nfs-ganesha-utils nfs-ganesha-vfs nfs-ganesha-xfs redis 
varnish 

For those that would like to use jemalloc-4.0 on epel, I have built packages for epel 5, 6, and 7 as well. These will not be pushed to the official epel mirrors, as there are api and abi changes that make them binary incompatible with the existing packages in epel.

I have my happy day job at Redpill Linpro in Norway. Redpill Linpro is the market leader for professional Open Source and Free Software solutions in the Nordics, though we have customers from all over. For professional managed services, all the way from small web apps, to massive IPv4/IPv6 multi data center media hosting, and everything through container solutions, in-house, cloud, and data center, contact us at http://www.redpill-linpro.com, or follow us on social media:

hitch-1.0.0-beta for Fedora and EPEL

Friday, June 26th, 2015

The Varnish project has a new little free software baby arriving soon: Hitch, a scalable TLS proxy. It will also be made available with support by Varnish Software as part of their Varnish Plus product.

A bit of background:

Varnish is a high-performance HTTP accelerator, widely used over the Internet. To use varnish with https, it is often fronted by other general http/proxy servers like nginx or apache, though a more specific proxy-only high-performance tool would be preferable. So they looked at stud.

hitch is a fork of stud. The fork is maintained by the Varnish development team, as stud seems abandoned by its creators, after the project was taken over by Google, with no new commits after 2012.

I wrapped hitch for fedora, epel6 and epel7, and submitted them for Fedora and EPEL. Please test the latest builds and add feedback: https://admin.fedoraproject.org/updates/search/hitch . The default config is for a single instance of hitch.

The package has been reviewed and was recently accepted into Fedora and EPEL (bz #1235305). Update august 2015: Packages are pushed for testing. They will trickle down to stable eventually.

Note that there also exists as a fedora package of the (old) version of stud. If you use stud on fedora and want to test hitch, the two packages may coexist, and should be able to install in parallel.

To test hitch in front of varnish, in front of apache, you may do something like this (tested on el7):

  • Install varnish, httpd and hitch
      sudo yum install httpd varnish
      sudo yum --enablerepo=epel-testing install hitch || sudo yum --enablerepo=updates-testing install hitch
    
  • Start apache
      sudo systemctl start httpd.service
    
  • Edit the varnish config to point to the local httpd, that is, change the default backend definition in /etc/varnish/default.vcl , like this:
      backend default {
        .host = "127.0.0.1";
        .port = "80";
      }
    
  • Start varnish
      sudo systemctl start varnish.service
    
  • Add an ssl certificate to the hitch config. For a dummy certificate,
    the example.com certificate from the hitch source may be used:

      sudo wget -O /etc/pki/tls/private/default.example.com.pem http://users.linpro.no/ingvar/varnish/hitch/default.example.com.pem
    
  • Edit /etc/hitch/hitch.conf. Change the pem-file option to use that cert
      pem-file = "/etc/pki/tls/private/default.example.com.pem"
    
  • Start hitch
      sudo systemctl start hitch.service
    
  • Open your local firewall if necessary, by something like this:
      sudo firewall-cmd --zone=public --add-port=8443/tcp
    
  • Point your web browser to https://localhost:8443/ . You should be greeted with a warning about a non-official certificate. Past that, you will get the apache frontpage through varnish and hitch.

    Enjoy, and let me hear about any interesting test results.

    Ingvar

    Varnish Cache is powerful and feature rich front side web cache. It is also very fast, that is, Fast as in on steroids, and powered by The Dark Side of the Force.

    Redpill Linpro is the market leader for professional Open Source and Free Software solutions in the Nordics, though we have customers from all over. For professional managed services, all the way from small web apps, to massive IPv4/IPv6 multi data center media hosting, and everything through container solutions, in-house, cloud, and data center, contact us at www.redpill-linpro.com.

  • varnish-4.0.3 for Fedora and EPEL

    Thursday, March 5th, 2015

    varnish-4.0.3 was released recently. I have wrapped packages for Fedora and EPEL, and requested updates for epel7, f21 and f22. They will trickle down as stable updates within some days. I have also built packages for el6, and after som small patching, even for el5. These builds are based on the Fedora package, but should be only cosmetically different from the el6 and el7 packages available from http://varnish-cache.org/.

    Also note that Red Hat finally caught up, and imported the necessary selinux-policy changes for Varnish from fedora into el7. With selinux-policy-3.13.1-23.el7, Varnish starts fine in enforcing mode. See RHBA-2015-0458.

    My builds for el5 and el6 are available here: http://users.linpro.no/ingvar/varnish/4.0.3/. Note that they need other packages from EPEL to work.

    Update 1: I also provide an selinux module for those running varnish-4.0 on el6. It should work for all versions of varnish-4.0, including mine and the ones from varnish-cache.org.

    Update 2: Updated builds with a patch for bugzilla ticket 1200034 are pushed for testing in f21, f22 and epel7. el5 and el6 builds are available on link above.

    Enjoy.

    Ingvar

    Varnish Cache is powerful and feature rich front side web cache. It is also very fast, that is, Fast as in on steroids, and powered by The Dark Side of the Force.

    Redpill Linpro is the market leader for professional Open Source and Free Software solutions in the Nordics, though we have customers from all over. For professional managed services, all the way from small web apps, to massive IPv4/IPv6 multi data center media hosting, and everything through container solutions, in-house, cloud, and data center, contact us at redpill-linpro.com.