Over half an year later, I realized, that I never published my article about operating system and software setup of my Mini-PC router. This is a follow-up post about the Qotom-hardware I wrote earlier. So, its probably about time to do that!

To get the ball rolling on new CentOS installation, a good start is to download it, Rufus it into an USB-stick and install the minimal setup into router-PC. The CentOS installation is so well documented and trivial process, I won't go into any details of it. Read something like Installing Red Hat Enterprise Linux 7.4 on all architectures for details of that.

Goal

Every project needs a goal. In any kind of engineering there is a specification and criteria, that the goal has been met.

The goal of this project is to create a Linux-server capable of securing a local network from the Internet and allow traffic to pass from the LAN to the wild-wild-net.

Spec:

• There is a working CentOS Linux running on the MiniPC
• ISP's cable modem is configured as bridge, no double NATting done
  • MiniPC gets a public IP-address from ISP
  • MiniPC can be accessed from the Net via the IP-address
• Configurations persist a reboot on the MiniPC
• MiniPC issues dynamic IP-addresses to LAN-clients
• MiniPC acts as a caching nameserver to LAN-clients
  • Any requests from the Net are not served
• Wireless access point is configured not do do any routing, aka. it is in access point mode
• The setup is secure with attack surface minimized
• LAN IP-address range is 192.168.1.0/24

Definition of done:

• Internet works!
  • MiniPC can connect to net
  • MiniPC can be connected from net and LAN via SSH
  • Wired clients can connect to net via Ethernet cable without any manual configuration
  • Wireless clients can connec to the net via Wi-Fi without any manual configuration

Step 1: Packages

After minimal installation, the set of tools and packages required includes:
net-tools bind-utils screen tcpdump policycoreutils-python setools

• net-tools: mostly for netstat, using route or ifconfig is deprecated
• bind-utils: for dig and nslookup
• screen: for full-screen window manager
• tcpdump: taking a look into Ethernet and TCP/IP-packages, when something goes wrong, getting detailed view is very important
• policycoreutils-python setools: for managing SELinux

Step 2: Remove NetworkManager

Packages to install: -none needed-

Why a server would have GNOME NetworkManager installed on a server is beyond me. I simply cannot comprehend what CentOS-people are thinking, when they as default treat my server as a laptop. But the main thing is, that this piece of shit needs to go! The quicker, the better!

DANGER!

When you actually run the yum-command to remove NetworkManager, your system will lose all network connectivity. So, please, do run this at a console, not via SSH-connection.

DANGER!

Run command as root on console:

yum erase NetworkManager

Now your system's networking is royally messed up.

Step 3: Setup NICs

Packages to install: -none needed-

Check that NetworkManager created and left ifcfg-files into /etc/sysconfig/network-scripts/. If the appropriate ifcfg-files (one for each interface) are gone, you need to start learning how to write one fast. A good starting point on that would be RedHat Enterprise Linux 7 product documentation, Networking Guide, section 2.2 Editing Network Configuration Files.

LAN interface

Out of the two Ethernet-interfaces, 50/50 coin-flip ended as enp3s0 LAN and enp1s0 WAN. For any practical purposes, it really doesn't matter which one is which, but I'm describing here my setup. If you're using some other hardware, your interface names won't match those.

For any sensible use of your LAN-side, this interface should be connected to a network switch, so that your local network can be shared by your PC, Playstation, TV, Wi-Fi access point or whatever you have there running. Of course you can run it with only one host connected directly to the router.

This is critical: Your LAN-interface MUST have a static IP-address for it. It really cannot act as LAN-side of a router without one.

I chose my LAN to be private IP-range 192.168.1.0/24, so I edited /etc/sysconfig/network-scripts/ifcfg-enp3s0 to contain:

TYPE=Ethernet
BOOTPROTO=none
DEFROUTE=yes
IPV6INIT=yes
NAME=enp3s0
UUID=-don't-touch-this-
DEVICE=enp3s0
ONBOOT=yes

NETWORK=192.168.1.0
BROADCAST=193.168.1.255
USERCTL=no

IPADDR=192.168.1.1
PREFIX=24
IPV4_FAILURE_FATAL=no
IPV6_AUTOCONF=yes
IPV6_DEFROUTE=yes
IPV6_PEERDNS=yes
IPV6_PEERROUTES=yes
IPV6_FAILURE_FATAL=no

WAN interface

For WAN, there is no need to touch enp1s0 setup (much). When your WAN-interface (enp1s0) starts, it will obtain an IP-address from your ISP. With that, it will also get your ISP's DNS-address an overwrite your precious manual changes in /etc/resolv.conf. You don't want that to happen. So, prevent that and edit /etc/sysconfig/network-scripts/ifcfg-enp1s0 and add:

PEERDNS="no"

Well, that was easy!

IP-forwarding

For routing to work, it requires Linux kernel to have IP-forwarding enabled. It will allow network packets to travel between interfaces.

Enable IP-forwarding immediately:

sysctl -w net.ipv4.ip_forward=1

Enable IP-forwarding on boot:

sysctl net.ipv4.ip_forward > /etc/sysctl.d/1_ip_forward.conf

Finalize network setup

When your network interface configurations are ok, restart everything by running following as root:

systemctl enable network
systemctl restart network

Now your system:

• has both interfaces on-line
• is reachable from a machine on your wired-LAN using a static IP-address other than 192.168.1.1.
  Note: your router doesn'ht have DHCPd running yet, so you need to figure out how to configure a static IP-address to your device
• still gets an IP-address from your ISP from your external interface
• can reach IP-addresses via both external and internal interfaces

If these criteria are not met, there is simply no point in proceeding. Your system won't work as a router without those prerequisites.

Finally, make sure that your IPtables-rules have effect. Your box is connected to Internet and it can be accessed/bombarded from there, so run following to secure your setup:

systemctl restart firewalld

Now your system is ready to become a router.

Step 4: Firewalld

Packages to install: -none needed-

Zones

Out-of-box CentOS has firewalld enabled. It has only one zone defined for public wild-wild-net, also TCP/22 SSH is open for the world. This needs to be run as root. First split off LAN into own zone home:

# firewall-cmd --zone home --change-interface enp3s0 --permanent

Check the zones and their assigned interfaces:

# firewall-cmd --get-active-zones
home
  interfaces: enp3s0
public
  interfaces: enp1s0

Setup network address translation (NAT) and allow traffic to flow from your LAN to outside world. Any relevant traffic is allowed to flow in from Internet back to your LAN. Commands to run:

# firewall-cmd --permanent --direct --add-rule ipv4 nat POSTROUTING 0 -o enp1s0 -j MASQUERADE
# firewall-cmd --permanent --direct --add-rule ipv4 filter FWDI_home_allow 0 -o enp1s0 -j ACCEPT
# firewall-cmd --permanent --direct --add-rule ipv4 filter FWDI_public_allow 0 -o enp3s0 -m state --state RELATED,ESTABLISHED -j ACCEPT

Enable the DNS-server we'll setup later, also disable any outgoing DNS-queries from your LAN (a security measure):

# firewall-cmd --permanent --zone home --add-service dns
# firewall-cmd --permanent --direct --add-rule ipv4 filter FWDI_home_deny 0 -p udp -m udp --dport 53 -j REJECT

At this point do a reload:

# firewall-cmd --reload

... and test your firewall setup from router:

• You still must be able to access Internet from your router
• Your LAN does work at this point. A client with a static IP must be able to access Internet.

Step 5: Named

Packages to install: bind-chroot

You can continue to use your ISP's nameserver, but I never do that. It makes much more sense to have a caching nameserver running at your own router. This allows your box to go directly to Internet root servers and do all the name queries for you. In many countries ISPs intentionally drop some domains out or are forced by government to do that. Running your own resolver makes sure that you get all the records as is and in case of changes you can flush caches whenever you want and don't have to wait for a record to expire.

Out-of-box the BIND 9.9.4 does not server anybody else than localhost. To fix this, find following two lines in /etc/named.conf:

listen-on port 53 { 127.0.0.1; };
allow-query     { localhost; };

Edit them to contain:

listen-on port 53 { 127.0.0.1; 192.168.1.1; };
allow-query     { localhost; 192.168.1.0/24; };

Finally, change your system's default name resolver by editing /etc/resolv.conf to contain a single line:

nameserver 127.0.0.1

Start the server and enable it to start on boot:

systemctl start named-chroot
systemctl enable named-chroot

Now you're ready to test the setup. Just host www.google.com or your favorite site. Successful reply will include IP-address(es) for your query.

Now your caching nameserver is ready and most probably you'll never have to touch it again.

Step 6: DHCP

Packages to install: dhcp

Edit /etc/dhcp/dhcpd.conf and have it contain:

ddns-update-style interim;
ignore client-updates;
authoritative;
default-lease-time 14400;
max-lease-time 86400;
option subnet-mask 255.255.255.0;
option broadcast-address 192.168.1.255;
option routers 192.168.1.1;
option domain-name "my.own.lan";
option domain-name-servers 192.168.1.1;
subnet 192.168.1.0 netmask 255.255.255.0 {
        range 192.168.1.50 192.168.1.99;
}

That piece of configuration will use your router as DNS for the clients and issue them addresses from range .50 - .99.

Start the server and enable it to start on boot:

systemctl start dhcpd
systemctl enable dhcpd

At this point, configure your client to use DHCP for IP-addressing. You must get an IP from the above range, also DNS-resolve and NAT should work, but that's the next step to do. Test it all.

Step 7: Testing it

Make sure:

1. A client in your LAN gets an IP-address from DHCP
2. A client in your LAN can ping your router at 192.168.1.1
3. A client in your LAN can ping something in the Internet, like Google's name server at 8.8.8.8
4. A client in your LAN resolves names, for example: nslookup www.google.com returns IP-addresses
5. A client in your LAN can access https://www.google.com/ via a web-browser

That's it! What else would you need?

Done!

Congratulations on your new router!

What I did next was set up my own DNS-zone so that my hosts had FQDNs. But that's beyond this blog post. Read something like How To Configure BIND as a Private Network DNS Server on CentOS 7 by DigitalOcean for that.

UUUJEA!

Com Hem has been rolling out a native SLAAC/DHCPv6-based IPv6 to it's entire customer base, and they took a very important step 2 in their project. They started honoring Prefix Delegation -requests! To a non-network person that means absolutely nothing, but to a network administrator that is really a game changer!

Normally I don't use much of the features my Sagemcom cable-TV -router has, it's just set to bridge:

Since I failed earlier to get a prefix from my ISP, I was toying around with my router and set it to router-mode, and to my great surprise:

The thing issued my LAN a /64 IPv6-network! Nice.
After putting everything back and eye-balling the DHCPv6 lease file on my Linux-router:

lease6 {
  interface "enp1s0";
  ia-pd c4:d0:0a:85 {
    starts 1515858667;
    renew 302400;
    rebind 483840;
    iaprefix 2a04:ae00::/56 {
      starts 1515858667;
      preferred-life 604800;
      max-life 2592000;
    }
    option dhcp6.status-code success;
  }
}

Yes, it contains an ia-pd -section! The iaprefix from the file is mine, only mine, my precious address space!
I have no idea how long they have been honoring my PD-requests, but on December 17th they didn't.

A generally accepted IPv6-deployment principle is to follow RFC 5375 [IPv6 Unicast Address Assignment Considerations]'s suggestions and issue a minimum of /64 (18E IPv6 addresses) to customers. Since this /64 is completely useless for your own LAN, a second suggestion is to issue a /48 (1,2 million E IPv6 addresses) or /56 (4700E IPv6 addresses) prefix for consumer's own LANs.
Note: 18E is SI-prefix for exa, aka 10^18. A /64 IPv6 network has 18,446,744,073,709,551,616 unique addresses in it.

The numbers are astronomically big and it's quite easy to get confused and lose the perspective what they actually mean. A more concrete approach is, that by being issued a /56, I can now split my prefix into 256 separate /64 networks as I please. It's not like I need 256 LANs, I'm totally happy get even 1 of them to work!

Now I have my hands full to configure and test everything on my LAN. I need to make sure, that native-IPv6 works for wired and wireless toys I have here.

When first information about a severe security flaw in Intel CPUs came out, it was immediately obvious, that this one is huge. This is in the scale of a meteorite hitting The Earth.

Here is just one example of what can happen, when fixed Linux kernels are deployed. I've been pumping data points from my weather station to Weather Underground for couple of years. Now this is how they are able to display my data:

If you don't see any graphs or data points there, that's my point here! WU does not work!

Yesterday I got an e-mail from them explaining the problems they're facing:

The interruption of service was related to the hot patches applied to our servers to correct the recent Intel hardware security flaws. We can say with 100% confidence that the data you share with us is completely safe. The patches required systems to be rebooted and, as these systems came back online, many of them did not boot up cleanly.

That is most definitely not the entire truth. The quality of their service at the time of writing this blog post is simply crap! Looks like Meltdown mitigation hit them harder than they anticipated.

 

I came back from Christmas holidays on Tuesday 2nd January and quite soon that morning our corporate chat channels were buzzing about this "Intel CPU flaw". Lot of the information came from article The mysterious case of the Linux Page Table Isolation patches. At the end, the author of the post suggests "Invest in popcorn, 2018 is going to be fun". For something written on first day of the year 2018, that is pretty well said!

More and more details leaked on Wednesday 3rd. The Register article Kernel-memory-leaking Intel processor design flaw forces Linux, Windows redesign suggested said, that Linux kernel team named the flaw as Forcefully Unmap Complete Kernel With Interrupt Trampolines, aka FUCKWIT. So, they must have been mighty annoyed by this one. Urban Dictionary has a rather hilarious explanation of it.

Given the time difference between US an Europe, the information was published late on 3rd January, in form of website Meltdown and Spectre - Vulnerabilities in modern computers leak passwords and sensitive data. On Thursday 4th European time, entire Internet was full of news and speculation of these security flaws. Nobody has really confirmed this, but it looks like Intel knew about this flaw back in June 2017, for example Ubuntu-project confirms, that they received information about the flaw back in November 9th.

So, what is fuss this all about?

Since nobody really understands Kernel page-table isolation or Speculative execution, a much simper approach is needed to get a grasp of this problem (yes, you Super-Nerds understand it, I know!).
Xkcd #1938 has the best summary of this flaw that I've seen:

Mr. Daniel Miessler also has pretty good summary of the problem in his post A Simple Explanation of the Differences Between Meltdown and Spectre:

Ultimately you have two choices:

1. Have a computer, which has a serious exploitable security flaw
2. Lose some of your CPU-power

Most cases door #1 is chosen for you by your operating system vendor or cloud service provider.

A real measured effect of the fix

This is what Epic Games measured for their game Fortnite:

While looking at the graph, please remember, that Epic Games didn't choose to have the fix installed. This decision was made for them thanks to cloud computing.

There are number of similar reports all around the web, including Tim Gostony's tweet "Impact of the patch for the Intel bug on my AWS EC2 instances running Linux". It shows much les bump in the CPU-power than Epic Games' graph, but still it is there and it can be noticed.

What now?

Ok, everybody's every CPU is affected, but luckily for Meltdown mitigation you wouldn't normally run malware on your computer anyway. For Spectre, it gets scary. It mostly affects shared computers where somebody else is capable of stealing data from your instance.

The #1 thing I'll be waiting most is a physical CPU product that can be purhcased from a store which has a fix for this. Nobody has even promised anything about that. The existing software-based fixes are horrible. For example I was running Progress Quest on a Windows 93 session on a i7 laptop. After the fix, simply starting Windows 93 on a web browser it takes almost all of the CPU instead of idling like it did before the fix.

Amazon Web Services (AWS) in their original statement they said that "This is a vulnerability that has existed for more than 20 years in modern processor architectures like Intel, AMD, and ARM across servers, desktops, and mobile devices." I'm hoping, that it will take less than a decade to get it fixed.

As usual, I got an e-mail from my NAS-box stating, that it has a new firmware upgrade QTS 4.3.3.0404 build 20171213.

It had the usual release notes telling the changes. What really caught my attention was:

QTS 4.3.3 is the final available firmware update for the following models: TS-419U II

WHAAT! Just out of the blue, my model was obsoleted piece of junk!

The actual full list of models is: TS-112P, TS-212P, TS-212-E, HS-210, TS-112, TS-212, TS-121, TS-221, TS-421 TS-120, TS-220, TS-420, TS-420U, TS-421U TS-412, TS-412U, TS-419U, TS-419U+, TS-419U II, TS-119P II, TS-219P II, TS-419P II, TS-119P+, TS-219P+, TS-419P+, TS-119P, TS-219P, TS-419P, TS-119, TS-219, TS-419

So, only the recent QNAP boxes were maintained from this point on. Darn! My take on their decision to stop maintaining all the old models is, that initially they barely maintained them at all. In fact, QNAP got burned seriously on not acting: 0-day: QNAP NAS Devices suffer of heap overflow. In less than two years they managed to get that one fixed. They received information on 1st Feb 2016, stalled on the fix and after 12 months somebody else stumbled into the same flaw and after QNAP failed to receive the information about it, he released into public. QNAP managed to the fix out at 14th Feb 2017.

To me that action (read: lack of it) means, that they did not have a protocol in place for a situation where a security flaw would be found in one of (read: all of) their main products sold to general public. While spewing out unfounded allegations here, I'm pretty confident, that it wouldn't have made any difference if the security flaw was in their internal systems. Also, I'm sure, they did not act on the initial report as the author was well-behaving and extended his grace period on QNAP's request. Unfortunately to QNAP, their security reporting system wasn't maintained and it didn't work at the time of second finding, so the information leaked quite soon.

After all this commotion, they chose to create processes, assign personnel to it and start maintaining their products, they suddenly realized, that IT'S HARD WORK! Oh really! Rest of the world knows it already. But that's what you need to do when you are in device manufacturing business. World is full of non-maintained IoT-junk, as this Twitter-feed points out.

Ok, enough rant. Now I have a decision to make. What to do with a perfectly good NAS-box. Suggestions are welcome.

Looks like I've been nice, as Santa Claus brought me a nice present. A Mini Arcade Machine!

By the looks of it, it must be some sort of Android device placed into an arcade cabinet.

There are 240 games to play, but none of them are well-known titles. Obviously, they didn't want to pay any royalties for using the names. However, all the games are classic ones which I've played couple decades ago.

What I was expecting to see is a HDMI-output, but there is none. All the gaming needs to be done on a tiny screen.

Problem

My gaming PC got the fall update quite late and after that it wouldn't stay in sleep. Something got broken in the update and I had to shut it down every single time I didn't want to use it. Annoying!

Debugging - The Reason

The reason it popped back on wasn't big of a mystery. There is a simple command to query the wake reason:

PS C:\WINDOWS\system32> .\powercfg.exe /waketimers
Timer set by [SERVICE] \Device\HarddiskVolume4\Windows\System32\svchost.exe (SystemEventsBroker) expires at 21:46:29 on 15.12.2017.
Reason: Windows will execute 'NT TASK\Microsoft\Windows\UpdateOrchestrator\Reboot' scheduled task that requested waking the computer.

There are number of articles about How to disable wake timers?, but it doesn't fix this.

A peek into Windows Task Scheduler reveals the ugly fact:

There is a hourly scheduled task, that indeed does run every hour and every goddamn hour it will wake my computer from the sleep to see if it needs to reboot it! Who having half a brain made that engineering decision at Microsoft?!

Attempt 1 - Disable the task - FAIL!

Ok, easy thing, let's disable the task. Or ... let's not. It is impossible! The permissions prevent regular human beings from doing that.

After a while, I bumped into somebody else having this same particular problem. Computer is waking up and: Can't modify task “Reboot” in win10 home. Basically, the idea is to go get Sysinternals PStools. It contains a tool called PSexec, which can do the modification for you.

Like this:

First run a cmd.exe with the PSexec 64-bit version:

PS D:\Users\Downloads> .\PsExec64.exe /s cmd.exe

Now, that permission-barrier is fixed, then:

C:\WINDOWS\system32>schtasks /change /tn "\Microsoft\Windows\UpdateOrchestrator\Reboot" /disable
SUCCESS: The parameters of scheduled task "\Microsoft\Windows\UpdateOrchestrator\Reboot" have been changed.

Now the stupid scheduled task is running hourly as expected, but NOT when your computer is sleeping. But ... guess what! Yes! There is something in Windows 10 internals, that keeps that particular task enabled. It will stay disabled for half an hour or so, but ultimately just using the computer makes the task enabled again, and the problem persists.

Attempt 2 - Remove the allow wake setting - FAIL!

By using the PsExec64.exe-trick, it is possible to get an XML-representation of the task, by running:
schtasks /tn "\Microsoft\Windows\UpdateOrchestrator\Reboot" /xml
in the XML-data there is:
<WakeToRun>true</WakeToRun>
... but I don't know how to change a task from XML-file. You can create a new one, but changing seems impossible.

So, ultimately I had to find something else

Attempt 3 - Powershell - FAIL!

Instead of spawning a new cmd.exe, going for PowerShell has benefits - it can actually edit an existing task. There is a built-in applet Get-ScheduledTask, with appropriate counterpart for setting the properties.

Spawn a nice PowerShell-session with appropriate permissions:

.\PsExec64.exe /s powershell.exe

The shell is kinda dead, for example output is garbled and input editing has issues, but if you know what to run, it will do it given the correct permissions.

As suggested in use powershell to find scheduled tasks set to wake the computer, now it is possible to get a list of Scheduled Tasks which have permission to wake the computer:

PS C:\WINDOWS\system32> Get-ScheduledTask | where {$_.settings.waketorun}

My computer will output a list like:

TaskPath                               TaskName
--------                               --------
\Microsoft\Windows\.NET Framework\     .NET Framework NGEN v4.0.3031...
\Microsoft\Windows\.NET Framework\     .NET Framework NGEN v4.0.3031...
\Microsoft\Windows\SharedPC\           Account Cleanup
\Microsoft\Windows\UpdateOrchestrator\ Reboot

A simple(?) one-liner will edit the task (backtick is the word-wrap operator):

Get-ScheduledTask `
  -TaskPath \Microsoft\Windows\UpdateOrchestrator\ `
  -TaskName Reboot |
  %{ $_.Settings.WakeToRun = $false ; `
  Set-ScheduledTask -TaskName $_.TaskName -TaskPath $_.TaskPath -Settings $_.Settings }

Yes, now the task is enabled, but has the appropriate condition setting for allow wake the computer from sleep disabled.

... aaaand it doesn't work. The same thing altering the enabled-state also resets this setting. Darn!

Attempt 4 - Revoke permissions - Success!

This was driving me mad!

It worked perfectly before the stupid update!

Finally, I found an article from Reddit: Is there ANY way to stop UpdateOrchestrator for turning 'wake the computer to run this task' back on after every cumulative update?

That guy suggested to revoke all permissions from the file. Now the automator which keeps resetting the settings fails to touch the file.

The command I ran in PowerShell is:

icacls $env:windir"\System32\Tasks\Microsoft\Windows\UpdateOrchestrator\Reboot" `
  /inheritance:r `
  /deny "Everyone:F" `
  /deny "SYSTEM:F" `
  /deny "Local Service:F" `
  /deny "Administrators:F"

That simply puts everybody and everything into deny-list for the file-access. AND IT WORKS!

So, looks like ultimately whatever the mechanism is restoring the setting, somebody loves writing to the file, but it doesn't know how to reset the permissions. Which is nice!

I chose to keep the task enabled, but unset the allow wake -setting. So, when my computer is running, the task is ran every hour as expected, but when my computer is sleeping, my computer is sleeping and doesn't wake for nobody.

Microsoft:
Suggestion, eat your own dog food! If anybody at the Windows-team doing power management/task scheduler would run this at home they would know the annoyance instantly.

A month ago my ISP sent information that they're upgrading my connection speed without increasing the monthly cost! Nice. Totally unexpected from them.

Couple weeks ago my internet connection had dropped during night and I just flicked the switch on the cable router and it all came back. What I didn't initially realize, that I had an IPv6-address! WHOA!

Given zero public information about this on their public website, customer portal or anywhere, I just saw that on my network interface while investigating an another issue. They are broadcasting router advertisements and allocating a /64 from 2A04:AE00::/26 (SE-COMHEM-20140210). It looks like this on radvdump:

interface enp1s0 {
   AdvSendAdvert on;
   # Note: (Min,Max)RtrAdvInterval cannot be obtained with radvdump
   AdvManagedFlag on;
   AdvOtherConfigFlag on;
   AdvReachableTime 600000;
   AdvRetransTimer 0;
   AdvCurHopLimit 64;
   AdvDefaultLifetime 9000;
   AdvHomeAgentFlag off;
   AdvDefaultPreference high;
   AdvSourceLLAddress on;
   AdvLinkMTU 1500;
}; # End of interface definition

Since the O-bit for "other" (AdvOtherConfigFlag on) is enabled, it means that a DHCPv6-request will get more usable information. A DHCPv6 lease will look like this:

lease6 {   interface "enp1s0";
  ia-na xx:xx:xx:xx {
    starts 1512476381;
    renew 302400;
    rebind 483840;
    iaaddr 2a04:ae07:yyyy:yy::yyyy {
      starts 1512476381;
      preferred-life 604800;
      max-life 2592000;
  }
  option dhcp6.status-code success;
  }
  option dhcp6.client-id 0:1:2:3:4:5:6:7:8:9:a:b:c:d:e:f:10:11;
  option dhcp6.server-id 0:1:0:1:53:f:97:74:0:50:56:a8:22:a4;
  option dhcp6.name-servers 2a04:ae3a:ae3a::1,2a04:ae3a:ae3a::2;
}

It works and is fast and all, but ... (there's always the but part). Given SLAAC, they issue only a /64 prefix. Why is that a problem you ask. Well, to be able to issue an IPv6 address to all devices in my LAN, that's not enough.

I tried sending a Prefix Delegation -request via DHCPv6, but no. They didn't honor that request. Should that worked, I'd be happy. I'd have my own /48 prefix for my LAN-devices.

In the current form Com Hem's IPv6 is mostly useless as none of my actual devices have IPv6 addresses in them. I'm investigating this and if/when I find a solution for this, I'll post something about it. Meanwhile, if you know how to get a prefix out of them, please inform!

Today, 6th of December 2017, Finland celebrates its 100 years of independency. That's very convenient, as I'm not there to celebrate with my fellow Finns!

Since somebody lured lot of other states to celebrate with them, lot of the world-known objects were light Finnish-blue. One location from the list is Globen ("-95 nevö föget!"), which is conveniently a brief tunnelbana ride away from my home. For some reason, there are no published pictures of Globen in it's celebratory lighting. So, here goes:

Ok. In reality, the place is called Ericsson Globe, but nobody calls it that. It's just Globen.

The fail

On a peaceful Sunday, I was just minding my own business and BOOM! Internet connection was gone. After a quick debugging session, restarting the router and eyeballing the LEDs, it was evident: something with my ISP Com Hem was down:

Ok, ISP down, what next?
I whipped up the iPhone and went for any possible service announcements. And yes, the above announcement was placed on my user account information. I was stunned by this, it was so cool to have:

• confirmation, that something was down with ISP: Yup, it's broken.
• that information tailored with the geographical location of my subscription: Yup, that fail affects you.

No Finnish ISP or telco has that. I was very impressed with such detail (and still am).

The fix

There is no way I'm sitting on my thumbs on such an event. I was just about to start playing Need for Speed and now Origin wouldn't even log me in, so, no Internet, no gaming.

I have an el-cheapo Huawei Android lying around somewhere, with a Swedish SIM-card in it. My dirt cheap subscription has couple of gigs data transfer per month in it, which I never use. I came up with a plan to temporarily use the cell phone as an Internet connection. The idea would be to hook it up into my Linux router with an USB-cable, make sure the Android pops up as a network interface and then configure the Linux to use that network interface as primary connection.

Thethering

I found tons of information about Android-tethering from Arch Linux wiki. It basically says:

1. Make sure your Android is newer than 2.2
2. Connect the phone to a Linux
3. Enable USB-tethering from the phone's connection sharing -menu
4. Confirm the new network interface's existence on the Linux end

On my phone, there was two settings for personal hotspot. Wifi/Bluetooth and USB:

Connection

New phones have USB-C, but its such a new connector type, that anything older than couple years, has most likely micro-USB -connector:

Hooking it up to a Linux will output tons of dmesg and and ultimately result in a brand new network interface:

# ip addr show
5: enp0s20u4u3:
    link/ether 82:49:a8:b4:96:c9 brd ff:ff:ff:ff:f
    inet 192.168.42.90/24 brd 192.168.42.255 scope
       valid_lft 3595sec preferred_lft 3595sec
    inet6 fe80::7762:e1a9:9fa:69f5/64 scope link
       valid_lft forever preferred_lft forever

Routing configuration

Now that there was a new connection, I tried pinging something in the wild world:
ping -I enp0s20u4u3 193.166.3.2

Nope. Didn't work.
I confirmed, that the default network gateway was still set up into the broken link:
# ip route show
default via 192.168.100.1 dev enp1s0 proto static metric 100

That needs to go to enable some functionality. But what to replace the bad gateway with?
Since the connection had IP-address from Telco DHCP, there is a lease-file with all the necessary information:
# cat /var/lib/NetworkManager/dhclient-*-enp0s20u4u3.lease
lease {
  interface "enp0s20u4u3";
  fixed-address 192.168.42.90;
  option subnet-mask 255.255.255.0;
  option routers 192.168.42.129;

The fixed-address in the file matches the above ip addr show -information. Required information was gathered, and the idea was to ditch the original gateway and replace it with a one from the Android phone's telco:
# ip route del default via 192.168.100.1
# ip route add default via 192.168.42.129 dev enp0s20u4u3
# ip route show
default via 192.168.42.129 dev enp0s20u4u3 proto static metric 101

Now it started cooking:
# ping -c 5 ftp.funet.fi
PING ftp.funet.fi (193.166.3.2) 56(84) bytes of data.
64 bytes from ftp.funet.fi (193.166.3.2): icmp_seq=1 ttl=242 time=35.6 ms
64 bytes from ftp.funet.fi (193.166.3.2): icmp_seq=2 ttl=242 time=31.7 ms

To finalize the access from my LAN, I ran following firewall-cmd --direct commands:
 --remove-rule ipv4 nat POSTROUTING 0 -o enp1s0 -j MASQUERADE
 --add-rule ipv4 nat POSTROUTING 0 -o enp0s20u4u3 -j MASQUERADE
 --add-rule ipv4 filter FORWARD 0 -i enp3s0 -o enp0s20u4u3 -j ACCEPT
 --add-rule ipv4 filter FORWARD 0 -i enp0s20u4u3 -o enp3s0 \
    -m state --state RELATED,ESTABLISHED -j ACCEPT

There is no firewall-cmd --permanent on purpose. I don't intend those to stick too long. I just wanted to play the darn game!

Done!

Now my gaming PC would connect to The Big Net. I could suft the web, read mail and even Origin logged me in.

That's it! Day saved!

Update 25th June 2019: EBN scammers bankrupt

Roughly an year ago I posted about EBN European Business Number scam. Now, an year later, it is one of the most commented article on my blog. At the time of posting, I was just pissed off about that stupid scam and wanted to inform and educate my readers about this and warn them for NOT to agree on their terms, nor pay anybody any money for it.

Then something that I didn't foresee or expect to happen happened: The article took off and thousands of people read it and dozens commented it. Looks like I stumbled into something big. The upcoming months proved, that this scamming corporation was operating all over Europe and doing their less-than-honest "business" of selling nothingness to unwary business owners.

Given the flood of comments, recently I found out that Raivo Laanemets, an Estonian software consultant, wrote about EBN scam back on 2015, over year before I did. Go read his blog post here. For the pointer, I'd like to thank Mr. Vaidas, who copy/pasted the comment from Mr. Laanemets' blog to mine.

This is the comment from June 2017 and contains following by Mr.(?) Gorila:

The critical claims made are:

1. Person behind all this is Adrian Wittmer
   • My comment: I'm not sure how to confirm this
2. Mentioned Adrian Wittmer is actively involved in two companies: Credit Business Resolution s.r.o. and CCF Credit Collection Factoring s.r.o.
   • My comment: I have not seen the threatening debt collector's letters, but in my previous EBN post comments, people have said, that the company doing the debt collecting is indeed Credit Collection Factoring s.r.o. from the Czech Republic
3. Czech Republic legislation is more tolerant towards fraudsters
   • My comment: I barely know parts of Finnish law, gaining understanding difference between German or Czech laws is way beyond me.
4. Regulation (EC) No 1896/2006 of the European Parliament and of the Council of 12 December 2006 creating a European order for payment procedure
   • My comment: The above mentioned regulation directs how payments of "low value" between companies. (16) says: "This would allow the court to examine prima facie the merits of the claim and inter alia to exclude clearly unfounded claims or inadmissible applications."
     Article 7 (d) and (e) define, that EBN debt collectors need to establish basis for their claim and appropriate evidence.
     Shortly: If EBN-scam can be proven as unfounded claim based on fraud, you don't have to pay.
5. Mr. Wittmer has created a money-making-machine. First he sells a non-existing "service" for European Business Number, then he acts as an enforcer to collect his own debt from customers refusing to pay.
   • My comment: Again, I'm not sure how to confirm this, but it sure looks like that!

What I found out to corroborate Mr.(?) Gorila's claims made is:

• A variation of EBN-scam has been running in Czech Republic since 1998. There is an article about the scam written in 2006.
• Articles about Intercable Verlag AG can be found back in 2003 in Swizerland.
• Intercable Verlag AG was raided by Swiss police in 2006 and placed in liquidation in 2009
• I found a ton of claims, that Mr. Wittmer was the managing director of Intercable Verlag, but was unable to verify that. I guess, I just have to assume, that the claim is true.
• Croatian authorities issued a warning against EBN scam in 2017. That binds Swiss Intercable Verlag AG into Dutch EU Business Register and German DAD Deutscher Adressdienst GmbH. That could be a proof, that same persons operate the scam.
• In September 2014 European Parliament issued a notice about on misleading offers from Deutsche Adressdienst GmbH (DAD). That document clearly states that all petitions against the DAD Gmbh have been "declared admissible".
  Shortly: You don't have to pay!

There seems to be a lot of truth in his(?) comment.

Do not pay!

When going gets tough for you, just refer to European Parliament Petition 1176/2013, Petition 1180/2013 and Petition 1556/2013 to the judge. That should make things bouncing your way.

One of my favorite sites, StackOverflow, released statistics from their job-section.What are the Most Disliked Programming Languages? To my personal surprise, Perl won the contest. Easily. Hands down easily! Here are the highligts:

As you can see the top-3 three really stand out of the rest! You can easily disregard 2nd and 3rd "best", as nobody really uses VBA or Delphi anymore. Unlike those, Perl is being used. Even your Linux has it installed. All, but the tiny distros pre-install it into base image. Also those popular Mint and similar have it as an option. The obvious reason why Perl is being installed used everywhere is the wide popularity back in the 90s. Perl pre-dates Linux and was pretty much the only scripting language in that era, if not counting BASH or Tcsh scripting. Then times changed and Perl paved the way for PHP, Ruby, Python and the likes.

I don't understand who would NOT love a programming language that can be written with shift-key pressed down all the time!

Here, I present some of the most beautiful pieces of code ever written in Perl (also known as Obfuscated Perl Contest):

• The 1st Annual Obfuscated Perl Contest, Best in "The Perl Journal" category:
  package S2z8N3;{
   $zyp=S2z8N3;use Socket;
       (S2z8N3+w1HC$zyp)&
   open SZzBN3,"<$0"
;while(<SZzBN3>){/\s\((.*p\))&/
    &&(@S2zBN3=unpack$age,$1)}foreach
  $zyp(@S2zBN3){
 while($S2z8M3++!=$zyp-
30){$_=<SZz8N3>}/^(.)/|print $1
      ;$S2z8M3=0}s/.*//|print}sub w1HC{$age=c17
;socket(SZz8N3,PF_INET,SOCK_STREAM,getprotobyname('tcp'))&&
connect(SZz8N3,sockaddr_in(023,"\022\x17\x\cv"))
       ;S2zBN3|pack$age}
   
• The 4st Annual Obfuscated Perl Contest, 3rd in Do Something Powerful category:
  $_=q(s%(.*)%$_=qq(\$_=q($1),$1),print%e),s%(.*)%$_=qq(\$_=q($1),$1),print%e
   
• The 5h Annual Obfuscated Perl Contest, Winner of The Old Standby category:
  #:: ::-| ::-| .-. :||-:: 0-| .-| ::||-| .:|-. :||
open(Q,$0);while(<Q>){if(/^#(.*)$/){for(split('-',$1)){$q=0;for(split){s/|
/:.:/xg;s/:/../g;$Q=$_?length:$_;$q+=$q?$Q:$Q*20;}print chr($q);}}}print"\n";
#.: ::||-| .||-| :|||-| ::||-| ||-:: :|||-| .

Who would ever hate that?

Look! Even this kitten thinks, it's just a concise form of programming. Nothing to be hated.

About Humble Bundle

Couple months ago there was a real good deal in Humble Bundle for eBooks. For those of you who don't know what Humble Bundle is, it's a for-business subsidiary of IGN Entertainment (which again is a subsidiary of Ziff Davis). Unlike regular charities , which just make a plea to give money to them, Humble Bundle makes deals with software vendors to sell products which are way past their prime money-making age. Their slice of the operation is ~20% and the rest goes to software vendors and the charity of your choosing. In many cases you can choose the charity:software-split from range 0-100% and if you feel like it, you can tip Humble Bundle with something extra.

They passed $100M USD donated in September 2017. As there are costs of running the business, they raked in money more than that, but so far nobody has proved that they wouldn't actually deliver on their charity-promise. They are doing business with major corporations and if Humble Bundle would be caught red-handed, they would face a horde of lawyers suing their asses. For the time being, I choose to believe that they keep their promises and occasionally when I see something interesting in their mailing list, keep sending my money to them.

About the author, Kevin Mitnick

Ok, enough Humble Bundle, this is supposed to be about the book.
Since the deal was sweet, I went for it and paid couple € for the de-luxe bundle of security-related books (I think the actual amount was in region of 25 €). They delivered the download link for unlocked PDFs instantly after my PayPal payment was accepted. So, now I'm a proud owner of 14 books about information security.

The one book that I really wanted was the famous Art of Deception by Kevin Mitnick, a reformed bad boy who turned white-hat hacking. A warrant to arrest him was issued back in 1992 and he managed to evade FBI till February 1995. Since there was no applicable legislation in USA to convict him from the cracks he made to various US Government agencies and private corporations, US Department of Justice managed to keep him incarcerated for 4 and half years without bail or trial. When he got released to general public, a judge slapped a 7 year ban for him not to profit from selling books or movies, still on 2002 he put together this book and managed to get it published. He also published a book The Art Of Intrusion: The Real Stories Behind The Exploits Of Hackers, Intruders, And Deceivers in 2005, but it's unclear to me did he profit from them at all. Wired confirms, that the ban from profiting ended in January 2007. If anybody knows that, please drop a comment.

About the book

Well, enough of the author, this is supposed to be about the book.
The stories about social engineering tricks either Mr. Mitnick pulled off himself or the stories he describes in his book are really intriguing. But at the same time the technical details are vastly outdated, remember it was published in 2002 and stories are from 60s to 90s. Reading stories about dial-up modems, faxes and landline telephone voice mails make me laugh in the wrong place of the story. So, while reading, I was constantly thinking if it would be possible to pull off a similar feat in the modern world.

The books is written on four sections. Parts 1 and 2 are more about how social engineering works. There is always sonebody with poor awareness, either by not doing what was instructed or the instructions are missing or poorly done to begin with. Part 3 contains the "war stories" how people were fooled to say or do something they wouldn't normally do and while doing it didn't understand the value of their deed to the opposing party. To summarize, it's never a single piece of information which can compromise your organization, it's always a combination of things. To pull off such a social engineering hack, you must have detailed information about procedures and find a weak spot there. Also, most of the hacks are done to multi-site corporations. If your organization is geographically bound to a single location, it will be very hard to call in and request something "for my boss" at the remote site. My experience about small and medium sized Finnish companies is, that most people know everybody at least by name. Any incoming call would immediately raise suspicion and would question the caller's true agenda and identity.

Part 4 contains instrictions how to prevent such socical engineering attacks. For anybody not making security policies that part might be little bit boring. Here is an example of a flowchart how to train personnel:

Copyright © 2002 by Kevin D. Mitnick

Given in modern world, that government organizations don't need to pull of such hacks to get your information. You've already volunteered all of that! All they need to do is capture it from your cloud service provider's hard drive. Also, generally speaking personnel are more aware of possibility for social engineering. In his CeBIT Global Conferences 2015 video he claims, that for example dumpster diving still works. I personally wouldn't believe it. In Europe we don't need to print source code o passwords to paper and if we would be that stupid, there is a special secret-material-to-be-destroyed -paper bin at the office for such confidential waste.

Also, I remember seeing a video (... which unfortunately I was unable to locate) of Mr. Mitnick describing an assignment he got from a company, where his social engineering failed. It happened, that the receptionist knew about it. When Mr. Mitnick was requesting for a piece of information to get his assignment going forward, the receptionist actually responded: "Have you heard of Kevin Mitnick's book Art of Deception?". So, that was an example of well trained personnel to save that day. But unfortunately the book doesn't have a single example of social engineering failing. I was kinda expecting to see some of those.

About recommendations: people already knowledgeable about social engineering and feats that Mr. Mitnick pulled off don't get that much out of the book, but for everybody else, the book offers mind-opening stories, which can be reflected in everybody's real life. When somebody asks you for something they should already know, it may be time to think about social engineering.

If you have 6 minutes to spare, here is a DEF CON 23 video of Mr. Mitnick pulling off a social engineering hack, with permission from the target corporation, targeted to a pre-selected employee. They lure the poor guy to go to a website using Internet Explorer, which at the time had a known security flaw in it. That way they get a some sort of remote-access-toolkit to his computer. Nice! But not possible without the actual injection using the flaw being there.

Which anti-virus software to use on a Windows 10?

There are a number of software to choose from. Some are free, some are really good at detecting malware, some are award winning, industry recognized pieces of software and there is even one that comes with your Windows 10 installation.

For couple decades, my personal preference has been a product from F-Secure. For those of you expecting me to hand out a recommedation out of numerous F-Secure products, given the multiple computers I operate on daily basis, just picking a single specific product is not possible. Also, I'm a member of their Beta Program and run couple pieces of their software which are not flagged as production-quality.

Here is the part with a recommendation:
When Ultralight Anti-Virus (for Windows) gets released, that's the one I definitely urge you to try out. The user interface is an oddball, simple, but odd:

On an initial glance, the first question I had was: "Ok, Where are the settings? Where IS the user interface?!" But that's the beauty of the product, it has no more settings than the above screenshot contains. That's wildly out-of-the-box. Functional, yes. But something completely different. Naturally it's a F-Secure product, and they don't make any compromises with ability to detect malware. It has no firewall or plugins to your browser or anything unnecessary.

When/If the product is ever released, go check it out!

Altough, I'm a Cygwin fan, I have to admit, that the X11-port is not one of their finest work. Every once in a while I've known to run it.

Since there are number of window managers made available for Cygwin, I found it surprisingly difficult to start using one. According to docs (Chapter 3. Using Cygwin/X) and /usr/bin/startxwin, XWin-command is executed with a -multiwindow option. Then XWin man page says: "In this mode XWin uses its own integrated window manager in order to handle the top-level X windows, in such a way that they appear as normal Windows windows."

As a default, that's ok. But what if somebody like me would like to use a real Window Manager?

When startxwin executes xinit, it optionally can run a ~/.xserverrc as a server instead of XWin. So, I created one, and made it executable. In the script, I replace -multiwindow with -rootless to not use the default window manager.

This is what I have:

#!/bin/bash

# If there is now Window Maker installed, just do the standard thing.
# Also, if xinit wasn't called without a DISPLAY, then just quit.
if [ ! -e /usr/bin/wmaker ] || [ -z "$1" ]; then
     exec XWin "$@"
     # This won't be reached.
fi

# Alter the arguments:
# Make sure, there is no "-multiwindow" -argument.
args_out=()
for arg; do
     [ $arg == "-multiwindow" ] && arg="-rootless"
     args_out+=("$arg")
done

exec XWin "${args_out[@]}" &

# It takes a while for the XWin to initialize itself.
# Use xset to check if it's available yet.
while [ ! DISPLAY="${args_out[0]}" xset q > /dev/null ]; do
     sleep 1
done
sleep 1

# Kick on a Window Manager
DISPLAY="${args_out[0]}" exec /usr/bin/wmaker &

wait

The script assumes, that there is a Window Maker installed (wmaker.exe). The operation requires xset.exe to exist. Please, install it from package xset, as it isn't installed by default.