Andy, do you run a mail relay/smarthost for customers?
I've got nullmailer running on one of my VPS, and it looks like I
configured it with a bitfolk.com smarthost, but it doesn't dig/accept SMTP
(so I'm guessing it either used to exist and doesn't any more, or it never
existed and I just made some shit up)
Kind regards
Murray Crane
Hi,
Has anyone else been seeing (what appears to be) DDOS attempts against
their VPS's?
I've been getting quite a lot of messages like this in my logs over the
past few days:
Sep 30 05:02:06 scruffy kernel: [2103474.700870] TCP: drop open request
from 45.195.133.8/51353
Sep 30 05:02:07 scruffy kernel: [2103476.223611] TCP: drop open request
from 149.56.180.255/25006
Sep 30 05:02:08 scruffy kernel: [2103476.704225] TCP: drop open request
from 45.195.133.8/7947
Sep 30 05:02:08 scruffy kernel: [2103476.713872] TCP: drop open request
from 149.56.180.255/31127
Any ideas also on the best way to block? (I was reading about SYN
cookies, but not sure if this is a good idea or not).
cheers,
Matt.
Hi,
If you aren't running 32-bit Ubuntu then you can probably skip this
message.
A customer reported that they'd updated their 32-bit Ubuntu 18.04
VPS and now the kernel doesn't boot. I had a look and indeed the
latest 32-bit linux-image-generic immediately kernel panics.
This means that if you're on 32-bit and you try to boot into it,
your VPS won't boot. Also it means that currently 32-bit Ubuntu
18.04 installs aren't possible because the installer kernel won't
boot.
I haven't yet had any reports of the same thing happening in other
versions of Ubuntu, but it might do since presumably there is some
security patch being pushed out (I'm going to take a wild stab at
32-bit KPTI protection) that is broken, so it might hit any
supported version of 32-bit Ubuntu.
The only quick way I have found to work around this at present is
to run a 64-bit kernel. Here's how you'd do that, assuming that your
VPS is currently unbootable.
xen-shell> rescue
(boot and log in to rescue VM)
$ sudo mount /dev/xvda1 /mnt
$ sudo mount --bind /dev /mnt/dev
$ sudo mount --bind /sys /mnt/sys
$ sudo mount --bind /proc /mnt/proc
$ sudo chroot /mnt /bin/bash
# dpkg --add-architecture amd64
# apt update
# apt install linux-image-generic:amd64
# exit
$ sudo halt
xen-shell> arch x86_64
xen-shell> boot
This:
1) Enables multi-arch on your VPS and says that amd64 architecture
packages are acceptable
2) Installs a 64-bit kernel
3) Boots into it
You will then be running a 64-bit kernel with a 32-bit user land. It
should work fine and continue offering you updated 64-bit kernel
packages and updates 32-bit packages for everything else.
If you were brave you could completely cross-grade to amd64 but it
is a complicated, risky and unsupported procedure.
Another workaround may be to boot into rescue and do a chroot as
above, but then downgrade the kernel package.
I will attempt to replicate the problem and report it to Ubuntu.
Cheers,
Andy
--
https://bitfolk.com/ -- No-nonsense VPS hosting
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