I did some testing using strace and looking at backtraces of why "host"
is stuck, and it's not immediately clear to me why it's getting stuck.
Will need to look more in depth into it tracing it's actual execution -
it's multi threaded and using poll so not super straight forward from
the trace for someone unfamiliar with the code-base.
I did test that when it happens, the network interfaces are up and
systemd-resolved is started - and I can see a sendmsg/recvmsg appear to
succeed to the systemd stub resolver and my local SNS server. I also
tried explicitly setting the timeout with host -W 5 (this should be the
default, but wanted to test as there is a -w indefinite option).
However the 'host' command always works when I log into the system while
the other commands are still stuck in the background - so something
strange is going on.
What does work, is executing 'host' under /usr/bin/timeout. Given the
severity of this issue (makes startup hang without SSH for several
minutes, and blocks everything else from starting up seemingly forever),
I would suggest that we should ship a fix for bionic to use timeout to
work around the issue for now.
/usr/lib/avahi/avahi-daemon-check-dns.sh : dns_has_local()
OUT=`LC_ALL=C /usr/bin/timeout 5 host -t soa local. 2>&1`
** Changed in: openconnect (Ubuntu)
Status: Confirmed => Invalid
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https://bugs.launchpad.net/bugs/1752411
Title:
bind9-host, avahi-daemon-check-dns.sh hang forever causes network
connections to get stuck
Status in avahi package in Ubuntu:
Confirmed
Status in bind9 package in Ubuntu:
Confirmed
Status in openconnect package in Ubuntu:
Invalid
Bug description:
On 18.04 Openconnect connects successfully to any of multiple VPN
concentrators but network traffic does not flow across the VPN tunnel
connection. When testing on 16.04 this works flawlessly. This also
worked on this system when it was on 17.10.
I have tried reducing the mtu of the tun0 network device but this has
not resulted in me being able to successfully ping the IP address.
Example showing ping attempt to the IP of DNS server:
~$ cat /etc/resolv.conf
# Dynamic resolv.conf(5) file for glibc resolver(3) generated by resolvconf(8)
# DO NOT EDIT THIS FILE BY HAND -- YOUR CHANGES WILL BE OVERWRITTEN
# 127.0.0.53 is the systemd-resolved stub resolver.
# run "systemd-resolve --status" to see details about the actual nameservers.
nameserver 172.29.88.11
nameserver 127.0.0.53
liam@liam-lat:~$ netstat -nr
Kernel IP routing table
Destination Gateway Genmask Flags MSS Window irtt Iface
0.0.0.0 192.168.1.1 0.0.0.0 UG 0 0 0
wlp2s0
105.27.198.106 192.168.1.1 255.255.255.255 UGH 0 0 0
wlp2s0
169.254.0.0 0.0.0.0 255.255.0.0 U 0 0 0
docker0
172.17.0.0 0.0.0.0 255.255.0.0 U 0 0 0
docker0
172.29.0.0 0.0.0.0 255.255.0.0 U 0 0 0 tun0
172.29.88.11 0.0.0.0 255.255.255.255 UH 0 0 0 tun0
192.168.1.0 0.0.0.0 255.255.255.0 U 0 0 0
wlp2s0
liam@liam-lat:~$ ping 172.29.88.11
PING 172.29.88.11 (172.29.88.11) 56(84) bytes of data.
^C
--- 172.29.88.11 ping statistics ---
4 packets transmitted, 0 received, 100% packet loss, time 3054ms
ProblemType: Bug
DistroRelease: Ubuntu 18.04
Package: openconnect 7.08-3
ProcVersionSignature: Ubuntu 4.15.0-10.11-generic 4.15.3
Uname: Linux 4.15.0-10-generic x86_64
ApportVersion: 2.20.8-0ubuntu10
Architecture: amd64
CurrentDesktop: ubuntu:GNOME
Date: Wed Feb 28 22:11:33 2018
InstallationDate: Installed on 2017-06-15 (258 days ago)
InstallationMedia: Ubuntu 16.04.1 LTS "Xenial Xerus" - Release amd64
(20160719)
SourcePackage: openconnect
UpgradeStatus: Upgraded to bionic on 2018-02-22 (6 days ago)
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