Docker container not able to ping host

Question

I am following this tutorial

https://docs.docker.com/articles/networking/#between-containers

I have used following commands

$ sudo brctl addbr bridge0
$ sudo ip addr add 192.168.0.160/24 dev bridge0
$ sudo ip link set dev bridge0 up

# Confirming that our bridge is up and running

$ ip addr show bridge0
4: bridge0: <BROADCAST,MULTICAST> mtu 1500 qdisc noop state UP group default
    link/ether 66:38:d0:0d:76:18 brd ff:ff:ff:ff:ff:ff
    inet 192.168.0.160/24 scope global bridge0
       valid_lft forever preferred_lft forever

# Tell Docker about it and restart (on Ubuntu)

$ echo 'DOCKER_OPTS="-b=bridge0"' >> /etc/default/docker
$ sudo service docker start

It looks to work fine as i can see that my all conatiner are getting ip in that range.

Now as i have 3 conatiners

mysql 192.168.0.3
redis 192.168.0.5
webserver 192.168.0.6

Now if i ping redis from webserver it works

but i cma not able to ping the host 192.168.0.160 it says destination host unrecable

INFO

vagrant@ubuntu-docker-base:/mydocker/containers$ brctl show
bridge name bridge id       STP enabled interfaces
bridge0  8000.7e8945d   no  veth1a8b959
                            veth404a3b2
                            veth7959157
docker0     8000.5689799    no

container

root@286329032cd5:/# ip route
default via 192.168.0.160 dev eth0
192.168.0.0/24 dev eth0  proto kernel  scope link  src 192.168.0.5
root@286329032cd5:/# ping 192.168.0.3
PING 192.168.0.3 (192.168.0.3) 56(84) bytes of data.
64 bytes from 192.168.0.3: icmp_seq=1 ttl=64 time=0.125 ms
64 bytes from 192.168.0.3: icmp_seq=2 ttl=64 time=0.130 ms
64 bytes from 192.168.0.3: icmp_seq=3 ttl=64 time=0.072 ms
^C
--- 192.168.0.3 ping statistics ---
3 packets transmitted, 3 received, 0% packet loss, time 1998ms
rtt min/avg/max/mdev = 0.072/0.109/0.130/0.026 ms
root@286329032cd5:/# ping 192.168.0.160
PING 192.168.0.160 (192.168.0.160) 56(84) bytes of data.
From 192.168.0.5 icmp_seq=1 Destination Host Unreachable
From 192.168.0.5 icmp_seq=2 Destination Host Unreachable
From 192.168.0.5 icmp_seq=3 Destination Host Unreachable
^C
--- 192.168.0.160 ping statistics ---
6 packets transmitted, 0 received, +3 errors, 100% packet loss, time 5032ms
pipe 3
root@286329032cd5:/#

Solution

I had a similar problem, where I wanted to connect from a docker container to its host for accessing a postfix and an apache server.

It helped to add such rules to the iptables of the host:

iptables -A INPUT -i docker0 -p tcp -m tcp --dport 25 -j ACCEPT
iptables -A INPUT -i docker0 -p tcp -m tcp --dport 80 -j ACCEPT

These ports were open before, but only for eth0 interface, not for docker0 ;)

Comments

[Admin]

@rjt The host ip is 192.168.0.8 which is docker host, which is connected to my router on eth0

[rjt]

What is the output of $ cat /proc/sys/net/ipv4/ip_forward on the host?

[Mirage]

I checked that its 1. i will try your fix when i go home. i was doing remotely and i think i meesed up with eth0 and now i have lost connectivity :)

[rjt]

Now that i have reread more of the tutorial, this answer most likely does not apply.