Category: Debian

Your Debian netboot suddenly can’t do Ext4?

Posted on by Andy

If, like me, you’ve just done a Debian netboot install over PXE and discovered that the partitioner suddenly seems to have no option for Ext4 filesystem (leaving only btrfs and XFS), despite the fact that it worked fine a couple of weeks ago, do not be alarmed. You aren’t losing your mind. It seems to be a bug.

As the comment says, downloading netboot.tar.gz version 20150422+deb8u3 fixes it. You can find your version in the debian-installer/amd64/boot-screens/f1.txt file. I was previously using 20150422+deb8u1 and the commenter was using 20150422+deb8u2.

Looking at the dates on the files I’m guessing this broke on 23rd January 2016. There was a Debian point release around then, so possibly you are supposed to download a new netboot.tar.gz with each one – not sure. Although if this is the case it would still be nice to know you’re doing something wrong as opposed to having the installer appear to proceed normally except for denying the existence of any filesystems except XFS and btrfs.

Oh and don’t forget to restart your TFTP daemon. tftpd-hpa at least seems to cache things (or maybe hold the tftp directory open, as I had just moved the old directory out of the way), so I was left even more confused when it still seemed to be serving 20150422+deb8u1.

Installing Debian by PXE using Supermicro IPMI Serial over LAN

Posted on by Andy
Contents
      1. BIOS settings
      2. Connecting to the IPMI serial
      3. DHCP and TFTP server
        1. DHCP
        2. TFTP
      4. Perform the install

Here’s how to install Debian jessie on a Supermicro server using PXE boot and the IPMI serial-over-LAN.

Using these instructions you will be able to complete an install of a remote machine, although you will initially need access to the BIOS to configure the IPMI part.

BIOS settings ^

This bit needs you to be in the same location as the machine, or else have someone who is make the required changes.

Press DEL to go into the BIOS configuration.

Under Advanced > PCIe/PCI/PnP Configuration make sure that the network interface through which you’ll reach your PXE server has the “PXE” option ROM set:

BIOS PSE option ROM

Under Advanced > Serial Port Console Redirection you’ll want to enable SOL Console Redirection.

BIOS serial console redirection

(Pictured here is also COM1 Console Redirection. This is for the physical serial port on the machine, not the one in the IPMI.)

Under SOL Console Redirection Settings you may as well set the Bits per second to 115200.

BIOS SOL redirection settings

Now it’s time to configure the IPMI so you can interact with it over the network. Under IPMI > BMC Network Configuration, put the IPMI on your management network:

IPMI network configuration

Connecting to the IPMI serial ^

With the above BIOS settings in place you should be able to save and reboot and then connect to the IPMI serial console. The default credentials are ADMIn / ADMIN which you should of course change with ipmitool, but that is for a different post.

There’s two ways to connect to the serial-over-LAN: You can ssh to the IPMI controller, or you can use ipmitool. Personally I prefer ssh, but the ipmitool way is like this:

$ ipmitool -I lanplus -H 192.168.1.22 -U ADMIN -a sol activate

The ssh way:

$ ssh ADMIN@192.168.1.22
The authenticity of host '192.168.1.22 (192.168.1.22)' can't be established.
RSA key fingerprint is b7:e1:12:94:37:81:fc:f7:db:6f:1c:00:e4:e0:e1:c4.
Are you sure you want to continue connecting (yes/no)?
Warning: Permanently added '192.168.1.22,192.168.1.22' (RSA) to the list of known hosts.
ADMIN@192.168.1.22's password:
 
ATEN SMASH-CLP System Management Shell, version 1.05
Copyright (c) 2008-2009 by ATEN International CO., Ltd.
All Rights Reserved 
 
 
-> cd /system1/sol1
/system1/sol1
 
-> start
/system1/sol1
press <Enter>, <Esc>, and then <T> to terminate session
(press the keys in sequence, one after the other)

They both end up displaying basically the same thing.

The serial console should just be displaying the boot process, which won’t go anywhere.

DHCP and TFTP server ^

You will need to configure a DHCP and TFTP server on an already-existing machine on the same LAN as your new server. They can both run on the same host.

The DHCP server responds to the initial requests for IP address configuration and passes along where to get the boot environment from. The TFTP server serves up that boot environment. The boot environment here consists of a kernel, initramfs and some configuration for passing arguments to the bootloader/kernel. The boot environment is provided by the Debian project.

DHCP ^

I’m using isc-dhcp-server. Its configuration file is at /etc/dhcp/dhcpd.conf.

You’ll need to know the MAC address of the server, which can be obtained either from the front page of the IPMI controller’s web interface (i.e. https://192.168.1.22/ in this case) or else it is displayed on the serial console when it attempts to do a PXE boot. So, add a section for that:

subnet 192.168.2.0 netmask 255.255.255.0 {
}
 
host foo {
    hardware ethernet 0C:C4:7A:7C:28:40;
    fixed-address 192.168.2.22;
    filename "pxelinux.0";
    next-server 192.168.2.251;
    option subnet-mask 255.255.255.0;
    option routers 192.168.2.1;
}

Here we set the network configuration of the new server with fixed-address, option subnet-mask and option routers. The IP address in next-server refers to the IP address of the TFTP server, and pxelinux.0 is what the new server will download from it.

Make sure that is running:

# service isc-dhcp-server start

DHCP uses UDP port 67, so make sure that is allowed through your firewall.

TFTP ^

A number of different TFTP servers are available. I use tftpd-hpa, which is mostly configured by variables in /etc/default/tftp-hpa:

TFTP_OPTIONS="--secure"
TFTP_USERNAME="tftp"
TFTP_DIRECTORY="/srv/tftp"
TFTP_ADDRESS="0.0.0.0:69"

TFTP_DIRECTORY is where you’ll put the files for the PXE environment.

Make sure that the TFTP server is running:

# service tftpd-hpa start

TFTP uses UDP port 69, so make sure that is allowed through your firewall.

Download the netboot files from your local Debian mirror:

$ cd /srv/tftp
$ curl -s http://ftp.YOUR-MIRROR.debian.org/debian/dists/jessie/main/installer-amd64/current/images/netboot/netboot.tar.gz | sudo tar zxvf -
./                
./version.info    
./ldlinux.c32     
./pxelinux.0      
./pxelinux.cfg    
./debian-installer/
./debian-installer/amd64/
./debian-installer/amd64/bootnetx64.efi
./debian-installer/amd64/grub/
./debian-installer/amd64/grub/grub.cfg
./debian-installer/amd64/grub/font.pf2
…

(This assumes you are installing a device with architecture amd64.)

At this point your TFTP server root should contain a debian-installer subdirectory and a couple of links into it:

$ ls -l .
total 8
drwxrwxr-x 3 root root 4096 Jun  4  2015 debian-installer
lrwxrwxrwx 1 root root   47 Jun  4  2015 ldlinux.c32 -> debian-installer/amd64/boot-screens/ldlinux.c32
lrwxrwxrwx 1 root root   33 Jun  4  2015 pxelinux.0 -> debian-installer/amd64/pxelinux.0
lrwxrwxrwx 1 root root   35 Jun  4  2015 pxelinux.cfg -> debian-installer/amd64/pxelinux.cfg
-rw-rw-r-- 1 root root   61 Jun  4  2015 version.info

You could now boot your server and it would call out to PXE to do its netboot, but would be displaying the installer process on the VGA output. If you intend to carry it out using the Remote Console facility of the IPMI interface then that may be good enough. If you want to do it over the serial-over-LAN though, you’ll need to edit some of the files that came out of the netboot.tar.gz to configure that.

Here’s a list of the files you need to edit. All you are doing in each one is telling it to use serial console. The changes are quite mechanical so you can easily come up with a script to do it, but here I will show the changes verbosely. All the files live in the debian-installer/amd64/boot-screens/ directory.

ttyS1 is used here because this system has a real serial port on ttyS0. 115200 is the baud rate of ttyS1 as configured in the BIOS earlier.

adtxt.cfg

From:

label expert
        menu label ^Expert install
        kernel debian-installer/amd64/linux
        append priority=low vga=788 initrd=debian-installer/amd64/initrd.gz --- 
include debian-installer/amd64/boot-screens/rqtxt.cfg
label auto
        menu label ^Automated install
        kernel debian-installer/amd64/linux
        append auto=true priority=critical vga=788 initrd=debian-installer/amd64/initrd.gz --- quiet

To:

label expert
        menu label ^Expert install
        kernel debian-installer/amd64/linux
        append priority=low console=ttyS1,115200n8 initrd=debian-installer/amd64/initrd.gz --- 
include debian-installer/amd64/boot-screens/rqtxt.cfg
label auto
        menu label ^Automated install
        kernel debian-installer/amd64/linux
        append auto=true priority=critical console=ttyS1,115200n8 initrd=debian-installer/amd64/initrd.gz --- quiet
rqtxt.cfg

From:

label rescue
        menu label ^Rescue mode
        kernel debian-installer/amd64/linux
        append vga=788 initrd=debian-installer/amd64/initrd.gz rescue/enable=true --- quiet

To:

label rescue
        menu label ^Rescue mode
        kernel debian-installer/amd64/linux
        append console=ttyS1,115200n8 initrd=debian-installer/amd64/initrd.gz rescue/enable=true --- quiet
syslinux.cfg

From:

# D-I config version 2.0
# search path for the c32 support libraries (libcom32, libutil etc.)
path debian-installer/amd64/boot-screens/
include debian-installer/amd64/boot-screens/menu.cfg
default debian-installer/amd64/boot-screens/vesamenu.c32
prompt 0
timeout 0

To:

serial 1 115200
console 1
# D-I config version 2.0
# search path for the c32 support libraries (libcom32, libutil etc.)
path debian-installer/amd64/boot-screens/
include debian-installer/amd64/boot-screens/menu.cfg
default debian-installer/amd64/boot-screens/vesamenu.c32
prompt 0
timeout 0
txt.cfg

From:

default install
label install
        menu label ^Install
        menu default
        kernel debian-installer/amd64/linux
        append vga=788 initrd=debian-installer/amd64/initrd.gz --- quiet

To:

default install
label install
        menu label ^Install
        menu default
        kernel debian-installer/amd64/linux
        append console=ttyS1,115200n8 initrd=debian-installer/amd64/initrd.gz --- quiet

Perform the install ^

Connect to the serial-over-LAN and get started. If the server doesn’t have anything currently installed then it should go straight to trying PXE boot. If it does have something on the storage that it would boot then you will have to use F12 at the BIOS screen to convince it to jump straight to PXE boot.

$ ssh ADMIN@192.168.1.22
ADMIN@192.168.1.22's password:
 
ATEN SMASH-CLP System Management Shell, version 1.05
Copyright (c) 2008-2009 by ATEN International CO., Ltd.
All Rights Reserved 
 
 
-> cd /system1/sol1
/system1/sol1
 
-> start
/system1/sol1
press <Enter>, <Esc>, and then <T> to terminate session
(press the keys in sequence, one after the other)
 
Intel(R) Boot Agent GE v1.5.13                                                  
Copyright (C) 1997-2013, Intel Corporation                                      
 
CLIENT MAC ADDR: 0C C4 7A 7C 28 40  GUID: 00000000 0000 0000 0000 0CC47A7C2840  
CLIENT IP: 192.168.2.22  MASK: 255.255.255.0  DHCP IP: 192.168.2.252             
GATEWAY IP: 192.168.2.1
 
PXELINUX 6.03 PXE 20150107 Copyright (C) 1994-2014 H. Peter Anvin et al    
 
 
 
 
 
 
                 ┌───────────────────────────────────────┐
                 │ Debian GNU/Linux installer boot menu  │
                 ├───────────────────────────────────────┤
                 │ Install                               │
                 │ Advanced options                    > │
                 │ Help                                  │
                 │ Install with speech synthesis         │
                 │                                       │
                 │                                       │
                 │                                       │
                 │                                       │
                 │                                       │
                 │                                       │
                 └───────────────────────────────────────┘
 
 
 
              Press ENTER to boot or TAB to edit a menu entry
 
 
  ┌───────────────────────┤ [!!] Select a language ├────────────────────────┐
  │                                                                         │
  │ Choose the language to be used for the installation process. The        │
  │ selected language will also be the default language for the installed   │
  │ system.                                                                 │
  │                                                                         │
  │ Language:                                                               │
  │                                                                         │
  │                               C                                         │
  │                               English                                   │
  │                                                                         │
  │     <Go Back>                                                           │
  │                                                                         │
  └─────────────────────────────────────────────────────────────────────────┘
 
 
 
 
<Tab> moves; <Space> selects; <Enter> activates buttons

…and now the installation proceeds as normal.

At the end of this you should be left with a system that uses ttyS1 for its console. You may need to tweak that depending on whether you want the VGA console also.

systemd on Debian, reading the persistent system logs as a user

Posted on by Andy

All the documentation and guides I found say that to enable a persistent journal on Debian you just need to create /var/log/journal. It is true that once you create that directory you will get a persistent journal.

All the documentation and guides I found say that as long as you are in group adm (or sometimes they say group systemd-journal) it is possible to see all system logs by just typing journalctl, without having to run it as root. Having simply done mkdir /var/log/journal I can tell you that is not the case. All you will see is logs relating to your user.

The missing piece of info is contained in /usr/share/doc/systemd/README.Debian:


Enabling persistent logging in journald
=======================================

To enable persistent logging, create /var/log/journal and set up proper permissions:

install -d -g systemd-journal /var/log/journal
setfacl -R -nm g:adm:rx,d:g:adm:rx /var/log/journal

-- Tollef Fog Heen <tfheen@debian.org>, Wed, 12 Oct 2011 08:43:50 +0200

Without the above you will not have permission to read the /var/log/journal//system.journal file, and the ACL is necessary for journal files created in the future to also be readable.

Paranoid, Init

Posted on by Andy

Having marvelled at the er… unique nature of MikeeUSA’s Systemd Blues: Took our thing (Wooo) blues homage to the perils of using systemd, I decided what the world actually needs is something from the metal genre.

So, here’s the lyrics to Paranoid, Init.

Default soon on Debian
This doesn’t help me with my mind
People think I’m insane
Because I am trolling all the time

All day long I fight Red Hat
And uphold UNIX philosophy
Think I’ll lose my mind
If I can’t use sysvinit on jessie

Can you help me
Terrorise pid 1?
Oh yeah!

Tried to show the committee
That things were wrong with this design
They can’t see Poettering’s plan in this
They must be blind

Some sick joke I could just cry
GNOME needs logind API
QR codes gave me a feel
Then binary logs just broke the deal

And so as you hear these words
Telling you now of my state
Can’t log off and enjoy life
I’ve another sock puppet to create

rsync: “Inflate (token) returned -5”

Posted on by Andy

Today one of my rsync backups began failing with:

inflate (token) returned -5
rsync error: error in rsync protocol data stream (code 12) at token.c(604) [receiver=3.0.3]
rsync: writefd_unbuffered failed to write 373 bytes [generator]: Broken pipe (32)
rsync error: error in rsync protocol data stream (code 12) at io.c(1544) [generator=3.0.3]

It was repeatable when trying to transfer the same file (a large gzipped SQL dump file).

It turned out to be a bug in that version of rsync.

rsync 3.0.3 comes with Debian lenny. In order to get a newer version I have had to use lenny-backports for this. That gets me rsync v3.0.7, which does not exhibit this bug.

(Yes, I am aware that squeeze has been released and this host should be upgraded to that. There is security support for lenny until at least February 2012.)

Linux, IPv6, router advertisements and forwarding

Posted on by Andy

By default, a Linux host on an IPv6 network will listen for and solicit router advertisements in order to choose an IPv6 address for itself and to set up its default route. This is referred to as stateless address autoconfiguration (SLAAC).

If you don’t want a host to automatically configure an address and route then you could disable this behaviour by writing “0” to /proc/sys/net/ipv6/conf/*/accept_ra.

Additionally, if the Linux host considers itself to be a router then it will ignore all router advertisements.

In this context, what makes the difference between router or not are the settings of the /proc/sys/net/ipv6/conf/*/forwarding files (or the net.ipv6.conf.*.forwarding sysctl). If you turn your host into a router by setting one of those to “1”, you may find that your host removes any IPv6 address and default route it learnt via SLAAC.

There is a valid argument that a router should not be autoconfiguring itself, and should have its addresses and routes configured statically. Linux has IP forwarding features for a reason though, and sometimes you want to forward packets with a Linux box while still enjoying autoconfiguration. In my case I have some hosts running virtual machines, with IPv6 prefixes routed to the virtual machines. I’d still like the hosts to learn their default route via SLAAC.

It’s taken me a long time to work out how to do this. It isn’t well-documented.

Firstly, if you have a kernel version of 2.6.37 or higher then your answer is to set accept_ra to “2”. From ip-sysctl.txt:

accept_ra – BOOLEAN

Accept Router Advertisements; autoconfigure using them.

Possible values are:

  • 0 Do not accept Router Advertisements.
  • 1 Accept Router Advertisements if forwarding is disabled.
  • 2 Overrule forwarding behaviour. Accept Router Advertisements even if forwarding is enabled.

Functional default:

  • enabled if local forwarding is disabled.
  • disabled if local forwarding is enabled.

This appears to be a type of boolean that I wasn’t previously familiar with – one that has three different values.

If you don’t have kernel version 2.6.37 though, like say, everyone running the current Debian stable (2.6.32), this will not work. Helpfully, it also doesn’t give you any sort of error when you set accept_ra to “2”. It just sets it and continues silently ignoring router advertisements.

fuuuuuuuuuuuuuuuuuuuuuu

Fortunately Bjørn Mork posted about a workaround for earlier kernels which I would likely have never discovered otherwise. You just have to disable forwarding for the interface that your router advertisements will come in on, e.g.:

# echo 0 > /proc/sys/net/ipv6/conf/eth0/forwarding

Apparently as long as /proc/sys/net/ipv6/conf/all/forwarding is still set to “1” then forwarding will still be enabled. Obviously.

Additionally there are some extremely unintuitive interactions between “default” and “all” settings you may set in /etc/sysctl.conf and pre-existing interfaces. So there is a race condition on boot between IPv6 interfaces coming up and sysctl configuration being parsed. martin f krafft posted about this, and on Debian recommends setting desired sysctls in pre-up headers of the relevant iface stanza in /etc/network/interfaces, e.g.:

iface eth0 inet6 static
    address 2001:0db8:10c0:d0c5::1
    netmask 64
# Enable forwarding
    pre-up echo 1 > /proc/sys/net/ipv6/conf/default/forwarding
    pre-up echo 1 > /proc/sys/net/ipv6/conf/all/forwarding
# But disable forwarding on THIS interface so we still get RAs
    pre-up echo 0 > /proc/sys/net/ipv6/conf/$IFACE/forwarding
    pre-up echo 1 > /proc/sys/net/ipv6/conf/$IFACE/accept_ra
    pre-up echo 1 > /proc/sys/net/ipv6/conf/all/accept_ra
    pre-up echo 1 > /proc/sys/net/ipv6/conf/default/accept_ra

You will now have forwarding and SLAAC.

everything went better than expected

Recently updated gnutls then found you can’t connect to LDAP?

Posted on by Andy

If you recently installed this update:

gnutls26 (2.4.2-6+lenny2) stable-security; urgency=high
  * Non-maintainer upload by the Security Team.
  * Fixed CVE-2009-2730: a vulnerability related to NUL bytes in
    X.509 certificate name fields. (Closes: #541439)
    GNUTLS-SA-2009-4

 -- Giuseppe Iuculano <iuculano@debian.org> Sun, 01 Nov 2009 21:29:06
+0100

and then found that your applications began failing to connect to your LDAP server, you may want to check that your SSL certificate is valid. Along with this update it seems that the default behaviour changed to being more strict. In my case I was using self-signed SSL certificates without the CA being available.

You can disable the verification if you don’t want it by adding:

TLS_REQCERT     never

in /etc/ldap/ldap.conf on each client machine.

New fileserver for home

Posted on by Andy

specialbrew's disks

Recently my fileserver, becks, was not only getting filled to capacity but was also undergoing some severe performance problems. It’s by no means a poorly-specced machine (not for home use anyway) but my use of rsnapshot has grown so much in the last 6 months that it was no longer up to the job.

Read on for the saga of its replacement.

Continue reading “New fileserver for home” →

Private voting in Debian?

Posted on by Andy

Martin, why would you want voting private? In most societies and voting systems people are entitled to their opinions, to state them, and campaign on behalf of others if they like.

Note that I’m not expressing any opinion on the content of these posts (I haven’t been following it and I’m not a DD anyway, so my opinion isn’t worth much), only that I can’t understand why you’d want to stop people making them.