docker swarm用到的端口

1. TCP port 2376：

• This port is used for secure Docker client communication.
• This port is required for Docker Machine to work.
• Docker Machine is used to orchestrate Docker hosts.

2. TCP port 2377

• This port is used for communication between the nodes of a Docker Swarm or cluster.
• It only needs to be opened on manager nodes.

3. TCP and UDP port 7946

• This port is used for communication among nodes (container network discovery).

4. UDP port 4789

• This port is used for overlay network traffic (container ingress networking).

4. If overlay network is created with encryption (--opt encrypted)

• It's required that ip protocol 50 (ESP) traffic is allowed.

如何enable/disable ip protocol 50:

$ sudo iptables -A INPUT -p esp -j ACCEPT
$ sudo iptables -A OUTPUT -p esp -j ACCEPT

注意esp是protocol，它没有tcp/udp里面的端口概念，例如你指定：

$ sudo iptables -A INPUT -p esp --dport <port> -j ACCEPT

命令行会直接报语法错误，--dport不支持。