How to force Java to use IPv4 instead IPv6?

Question

My Java browser plug-in is no longer working. When I open a page that has a Java element, Java cannot connect to the server.

After investigation, I found that Java was trying to use IPv6, while my network does not support IPv6, so Java always fails to connect.

I tried looking on Google and found that I should run Java with -Djava.net.preferIPv4Stack=true, but how can I pass this to the browser?

I use Google Chrome and Java 7 update 5.

Solution

Put the options in _JAVA_OPTIONS environment variable. How to do this is already described in various other posts – although they usually talk about setting PATH, but it's all the same.

For example, on Linux, put the following in your ~/.profile or ~/.bash_profile:

export _JAVA_OPTIONS="-Djava.net.preferIPv4Stack=true"

Comments

[harrymc]

Why don't you disable the IPv6 protocol so Java won't have this option.

[nyongrand]

it is a old story, I do not know if I've disable IPv6 protocol, seems to have, I've forgotten, what I remember is I remove Java 7 and replace it with Java 6

[harrymc]

Disabling is easy : see this.

[WestCoastProjects]

@harrymc always copy content: that link is dead.

[harrymc]

@javadba: Links are never dead : see the Wayback Machine, but it's outdated. Better google "Disable IPv6 On Windows" for half a million results.

[Jason S]

@harrymc Got 6.8 million results today :)

[nyongrand]

ok, thanks for your reply, although i use windows but your solution inspire me, thanks

[user2428118]

See for example this post for setting environment variables: superuser.com/questions/284342/…

[Ribo]

Why does Java 'prefer' IPV6? It seems to break code that was working.

[Adnan Ali]

How to set it in Windows ?

[Dr. Koutheir Attouchi]

@Ribo: By default, Java uses dual-stack IPv6 when possible, that is, it uses IPv6 sockets that also support IPv4 addresses. These sockets are still compatible with IPv4 applications by using IPv4-mapped addresses. Therefore, this is a backward-compatible behavior.

[MarcH]

IPv4-mapped addresses break proxies.