Why docker container are not able to reach outside of the host inspite of having all the required firewalls rules and ip_forward on Red Hat Enterprise Linux 7 ?
Issue
- Why docker container are not able to reach outside of the host inspite of having all the required firewalls rules and ip_forward on Red Hat Enterprise Linux 7 ?
1. iptables rules
Postrouting NAT rule
Chain POSTROUTING (policy ACCEPT 71 packets, 5159 bytes)
pkts bytes target prot opt in out source destination
3 252 MASQUERADE all -- * !docker0 172.17.0.0/16 0.0.0.0/0
Forward rule
Chain FORWARD (policy ACCEPT 0 packets, 0 bytes)
pkts bytes target prot opt in out source destination
697 58548 DOCKER-ISOLATION all -- * * 0.0.0.0/0 0.0.0.0/0
0 0 DOCKER all -- * docker0 0.0.0.0/0 0.0.0.0/0
0 0 ACCEPT all -- * docker0 0.0.0.0/0 0.0.0.0/0 ctstate RELATED,ESTABLISHED
697 58548 ACCEPT all -- docker0 !docker0 0.0.0.0/0 0.0.0.0/0
0 0 ACCEPT all -- docker0 docker0 0.0.0.0/0 0.0.0.0/0
2. sysctl ip_forward
[root@test1 sha256]# sysctl -a |grep ip_forward
net.ipv4.ip_forward = 1
Environment
- Red Hat Enterprise Linux 7
- docker package
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