1) The release of Ubuntu you are using, via 'lsb_release -rd' or System -> About Ubuntu
Ubuntu 16.04.1 LTS
2) The version of the package you are using, via 'apt-cache policy pkgname' or by checking in Software Center
Kernel version 4.4.0-36
3) What you expected to happen
MTU probing should work automatically, there should be no network connectivity problems due to too large MTU.
4) What happened instead
I'm having an Ubuntu 16.04 32bit installation running inside Virtualbox, inside Ubuntu 16.04 64bit installation. Let's call the virtualized server as A and the host server as B.
B is connected to Internet with static, public IP address. There are no problems in its network connectivity i.e. it can be reached well with any service from Internet.
A has been given a static, public IP address. Actually A is using B's network card in connecting, but in my earlier virtual server installations, this hasn't caused any problems. In earlier installations (14.04 and before), there were no problems with network connectivity.
Now, in the fresh 16.04.01 32bit installation on A (i.e. virtual host), it seems that MTU is not probed properly. For example, if I'm trying to have a SSH connection from some internet host into A, the SSH connection freezes in "expecting SSH2_MSG_KEX_ECDH_REPLY" phase.
I tried manually setting net.ipv4.tcp_mtu_probing value to 1 and also 2, but it did not help. After I manually set the MTU value for lower value, connectivity problems went away.
ProblemType: Bug
DistroRelease: Ubuntu 16.04
Package: linux-image-4.4.0-36-generic 4.4.0-36.55
ProcVersionSignature: Ubuntu 4.4.0-36.55-generic 4.4.16
Uname: Linux 4.4.0-36-generic i686
AlsaVersion: Advanced Linux Sound Architecture Driver Version k4.4.0-36-generic.
AplayDevices: Error: [Errno 2] No such file or directory: 'aplay'
ApportVersion: 2.20.1-0ubuntu2.1
Architecture: i386
ArecordDevices: Error: [Errno 2] No such file or directory: 'arecord'
AudioDevicesInUse: Error: command ['fuser', '-v', '/dev/snd/by-path', '/dev/snd/pcmC0D1c', '/dev/snd/pcmC0D0c', '/dev/snd/pcmC0D0p', '/dev/snd/controlC0', '/dev/snd/seq', '/dev/snd/timer'] failed with exit code 1:
Card0.Amixer.info: Error: [Errno 2] No such file or directory: 'amixer'
Card0.Amixer.values: Error: [Errno 2] No such file or directory: 'amixer'
Date: Tue Sep 13 10:02:55 2016
HibernationDevice: RESUME=UUID=20336914-b62e-40bb-9eb6-463cf6e159c6
IwConfig: Error: [Errno 2] No such file or directory: 'iwconfig'
Lsusb:
Bus 001 Device 002: ID 80ee:0021 VirtualBox USB Tablet
Bus 001 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
MachineType: innotek GmbH VirtualBox
ProcFB: 0 vboxdrmfb
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-4.4.0-36-generic root=UUID=952c3908-dbd9-48d0-899a-a3a14a678b7b ro splash quiet
RelatedPackageVersions:
linux-restricted-modules-4.4.0-36-generic N/A
linux-backports-modules-4.4.0-36-generic N/A
linux-firmware 1.157.3
RfKill: Error: [Errno 2] No such file or directory: 'rfkill'
SourcePackage: linux
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.bios.date: 12/01/2006
dmi.bios.vendor: innotek GmbH
dmi.bios.version: VirtualBox
dmi.board.name: VirtualBox
dmi.board.vendor: Oracle Corporation
dmi.board.version: 1.2
dmi.chassis.type: 1
dmi.chassis.vendor: Oracle Corporation
dmi.modalias: dmi:bvninnotekGmbH:bvrVirtualBox:bd12/01/2006:svninnotekGmbH:pnVirtualBox:pvr1.2:rvnOracleCorporation:rnVirtualBox:rvr1.2:cvnOracleCorporation:ct1:cvr:
dmi.product.name: VirtualBox
dmi.product.version: 1.2
dmi.sys.vendor: innotek GmbH
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