Author Archives: Simon

gentoo configure ipv6 and ipv4 dual stack

Due to lack of documentation I had a bit of trouble getting both default gateways to work. It is vital that both gateways are on a separate line in the config file. You must also use the CIDR notation for ipv4 too. You cannot mix the netmask and CIDR entries. This is my config file which works without a problem. The only think I have changed are the IP addresses I used the ones reserved for documentation.

/etc/conf.d/net

############################################################################################### config_eth0="198.51.100.2/24 2001:db8::2/48" ############################################################################################### routes_eth0="default via 198.51.100.1 default via 2001:db8::2" ###############################################################################################
You also need to make sure that you kernel supports ipv6 and you need iproute2. To check this run

# ip -6 addr show lo 1: lo: mtu 16436 inet6 ::1/128 scope host valid_lft forever preferred_lft forever(The above lines show things are working)

If you can see your loopback address ::1 you should be good to restart your network card to apply the new configuration. Or if you needed to recompile you kernel a reboot may be necessary. After that is done you can test the ipv6 connection with icmp6.

# ping6 -n google.com PING google.com(2a00:1450:4008:c01::8b) 56 data bytes 64 bytes from 2a00:1450:4008:c01::8b: icmp_seq=1 ttl=50 time=29.8 ms 64 bytes from 2a00:1450:4008:c01::8b: icmp_seq=2 ttl=50 time=28.5 ms 64 bytes from 2a00:1450:4008:c01::8b: icmp_seq=3 ttl=50 time=28.3 ms 64 bytes from 2a00:1450:4008:c01::8b: icmp_seq=4 ttl=50 time=28.4 ms ^C --- google.com ping statistics --- 4 packets transmitted, 4 received, 0% packet loss, time 3009ms rtt min/avg/max/mdev = 28.352/28.779/29.817/0.637 ms

That looks good we received an answer from google via ipv6. Another thing you should know is that you will need to create iptables rules for ip6tables. In the standard configuration all packets will be accepted which you might not want (default policy accept). Now you could think about reconfiguring your web services to use your ipv6 connection. You may also need to emerge your software with the ipv6 use flag to make use of the new connection. A useful tool for calculating ipv6 networks and subnets is net-misc/sipcalc Sipcalc is an advanced console-based IP subnet calculator. Have fun with your new ipv6 connection 🙂

ipv6 ready

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Our gentoo web servers now support ipv6. I configured the ipv6 IP addresses and the ipv6 dns records last week. We are ready for the next gen internet or 10-15 years of dual stack ipv4 and ipv6.

remove Guest Session from the Switch User list in the login manager

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This will remove your current user name display.

Edit the lightdm config file:

sudo gedit /etc/lightdm/lightdm.conf

And append this line to the end of the file:

allow-guest=false

Safe the file and either reboot your computer or restart lightdm

sudo /etc/init.d/lightdm restart

this will close any application you have running

add minimize maximize buttons to GNOME shell windows

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To get the windows buttons back in Ubuntu 12.04 precise pangolin. You can use the following shell command:

gconftool -s /apps/metacity/general/button_layout -t string menu:minimize,maximize,close

You can also change the order of the buttons by moving their names around. Moving the : symbol will change the side of the buttons.

Remove memtest86 from GRUB boot menu

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To get rid of the memtest86 option in the Ubuntu boot menu. Do the following:

sudo chmod -x /etc/grub.d/20_memtest86+

sudo update-grub

Thats it reboot to check it works.

ICELANDIA – Time-lapse Visuals from 64° North

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ICELANDIA – Time-lapse Visuals from 64° North from The Upthink Lab on Vimeo.

restart several init scripts at once

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I just came across this neat shell command to restart all courier services in one go:

find /etc/init.d/ | grep courier | while read line; do $line restart; done

You could replace the grep courier with any other name you would like to use. This is one of those things I love about Linux 🙂

Downloading missing apt repo keys from behind a firewall

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After installing a ubuntu 12.04 (precise) server on a host behind a firewall. I tried to update the apt repositories to install some software. And received the following error message:

W: GPG error: http://extras.ubuntu.com precise Release: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 16126D3A3E5C1192

So I tried to fetch the missing key with:

apt-key adv --keyserver keyserver.ubuntu.com --recv-keys 16126D3A3E5C1192

Which did not work because the firewall was blocking port 11371 which is needed to fetch the apt keys. What a pain there must be a way to fetch the keys via another port. Maybe port 80 which should be open in most cases. Then I came across this command which did the magic:

apt-key adv --keyserver hkp://keyserver.ubuntu.com:80 --recv-keys 16126D3A3E5C1192

This command fetches the missing keys via port 80 which worked for me. If you need more than one key just add them to the –recv-keys line seperated by a space. Thats it.