Two processes can bind to the same port

Bug #1720378 reported by Liam Young on 2017-09-29
6
This bug affects 1 person
Affects Status Importance Assigned to Milestone
linux (Ubuntu)
Medium
Unassigned
Xenial
Medium
Unassigned
Zesty
Medium
Unassigned

Bug Description

On both xenial and zesty apache and haproxy seem to be able to bind to the same port:

# netstat -peanut | grep 8776
tcp 0 0 0.0.0.0:8776 0.0.0.0:* LISTEN 0 76856 26190/haproxy
tcp6 0 0 :::8776 :::* LISTEN 0 76749 26254/apache2
tcp6 0 0 :::8776 :::* LISTEN 0 76857 26190/haproxy

I thought this should not be possible?

ProblemType: Bug
DistroRelease: Ubuntu 16.04
Package: linux-image-4.4.0-96-generic 4.4.0-96.119
ProcVersionSignature: Ubuntu 4.4.0-96.119-generic 4.4.83
Uname: Linux 4.4.0-96-generic x86_64
AlsaDevices:
 total 0
 crw-rw---- 1 root audio 116, 1 Sep 29 11:46 seq
 crw-rw---- 1 root audio 116, 33 Sep 29 11:46 timer
AplayDevices: Error: [Errno 2] No such file or directory: 'aplay'
ApportVersion: 2.20.1-0ubuntu2.10
Architecture: amd64
ArecordDevices: Error: [Errno 2] No such file or directory: 'arecord'
AudioDevicesInUse: Error: command ['fuser', '-v', '/dev/snd/seq', '/dev/snd/timer'] failed with exit code 1:
CRDA: N/A
Date: Fri Sep 29 14:15:26 2017
Ec2AMI: ami-00000193
Ec2AMIManifest: FIXME
Ec2AvailabilityZone: nova
Ec2InstanceType: m1.blue
Ec2Kernel: unavailable
Ec2Ramdisk: unavailable
IwConfig: Error: [Errno 2] No such file or directory: 'iwconfig'
Lsusb:
 Bus 001 Device 002: ID 0627:0001 Adomax Technology Co., Ltd
 Bus 001 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
MachineType: OpenStack Foundation OpenStack Nova
PciMultimedia:

ProcEnviron:
 TERM=screen
 PATH=(custom, no user)
 LANG=en_US.UTF-8
 SHELL=/bin/bash
ProcFB:

ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-4.4.0-96-generic root=LABEL=cloudimg-rootfs ro console=tty1 console=ttyS0
RelatedPackageVersions:
 linux-restricted-modules-4.4.0-96-generic N/A
 linux-backports-modules-4.4.0-96-generic N/A
 linux-firmware N/A
RfKill: Error: [Errno 2] No such file or directory: 'rfkill'
SourcePackage: linux
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.bios.date: 04/01/2014
dmi.bios.vendor: SeaBIOS
dmi.bios.version: 1.10.1-1ubuntu1~cloud0
dmi.chassis.type: 1
dmi.chassis.vendor: QEMU
dmi.chassis.version: pc-i440fx-zesty
dmi.modalias: dmi:bvnSeaBIOS:bvr1.10.1-1ubuntu1~cloud0:bd04/01/2014:svnOpenStackFoundation:pnOpenStackNova:pvr15.0.2:cvnQEMU:ct1:cvrpc-i440fx-zesty:
dmi.product.name: OpenStack Nova
dmi.product.version: 15.0.2
dmi.sys.vendor: OpenStack Foundation

Liam Young (gnuoy) wrote :
Ryan Beisner (1chb1n) on 2017-09-29
tags: added: uosci

This change was made by a bot.

Changed in linux (Ubuntu):
status: New → Confirmed
Joseph Salisbury (jsalisbury) wrote :

Did this issue start happening after an update/upgrade? Was there a prior kernel version where you were not having this particular problem?

Would it be possible for you to test the latest upstream kernel? Refer to https://wiki.ubuntu.com/KernelMainlineBuilds . Please test the latest v4.14 kernel[0].

If this bug is fixed in the mainline kernel, please add the following tag 'kernel-fixed-upstream'.

If the mainline kernel does not fix this bug, please add the tag: 'kernel-bug-exists-upstream'.

Once testing of the upstream kernel is complete, please mark this bug as "Confirmed".

Thanks in advance.

[0] http://kernel.ubuntu.com/~kernel-ppa/mainline/v4.14-rc2/

Changed in linux (Ubuntu):
importance: Undecided → Medium
Changed in linux (Ubuntu Xenial):
status: New → Incomplete
Changed in linux (Ubuntu):
status: Confirmed → Incomplete
tags: added: kernel-da-key
Changed in linux (Ubuntu Xenial):
importance: Undecided → Medium
Liam Young (gnuoy) wrote :

Thanks for the suggestions. I will try with an upstream kernel and also add steps for reproducing

Joseph Salisbury (jsalisbury) wrote :

Thanks. I can try to reproduce this issue if you list the steps.

Liam Young (gnuoy) wrote :

Thanks jsalisbury. Ill try on another kernel now.

The steps to reproduce on xenial:

sudo su -
apt install --yes apache2 haproxy
echo "

listen test
    bind *:8776
    bind :::8776

" > /etc/haproxy/haproxy.cfg

echo "
Listen 8776
<VirtualHost *:8776>
        DocumentRoot /var/www/html
</VirtualHost>
" > /etc/apache2/sites-enabled/01-test.conf

systemctl restart haproxy
systemctl restart apache2
netstat -peanut | grep 8776

Liam Young (gnuoy) wrote :

I've retested with linux-image-4.4.9-040409-generic_4.4.9-040409.201605041832_amd64.deb but the image seems to persist.

Liam Young (gnuoy) wrote :

kernel-bug-exists-upstream

Changed in linux (Ubuntu):
status: Incomplete → Confirmed
Changed in linux (Ubuntu Xenial):
status: Incomplete → Confirmed
Changed in linux (Ubuntu Zesty):
status: New → Confirmed
importance: Undecided → Medium
Joseph Salisbury (jsalisbury) wrote :

This issue appears to be an upstream bug, since you tested the latest upstream kernel. Would it be possible for you to open an upstream bug report[0]? That will allow the upstream Developers to examine the issue, and may provide a quicker resolution to the bug.

Please follow the instructions on the wiki page[0]. The first step is to email the appropriate mailing list. If no response is received, then a bug may be opened on bugzilla.kernel.org.

Once this bug is reported upstream, please add the tag: 'kernel-bug-reported-upstream'.

[0] https://wiki.ubuntu.com/Bugs/Upstream/kernel

Changed in linux (Ubuntu Zesty):
status: Confirmed → Triaged
Changed in linux (Ubuntu Xenial):
status: Confirmed → Triaged
Changed in linux (Ubuntu):
status: Confirmed → Triaged
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