InetAddress.isReachable

[Roedy Green]

InetAddress.isReachable always returns false. I am puzzled why.

My router is set to pass UDP port 7 through. I can ping google.ca.
--
Roedy Green Canadian Mind Products
http://mindprod.com

Responsible Development is the style of development I aspire to now. It can be summarized by answering the question, “How would I develop if it were my money?” I’m amazed how many theoretical arguments evaporate when faced with this question.
~ Kent Beck (born: 1961 age: 49) , evangelist for extreme programming.

 

[Roedy Green]

What timeout are you using? Too short a timeout may cause a false
return if the host takes too long to reach.

I was using 10 seconds. I'll try bumping up the TTL.
--
Roedy Green Canadian Mind Products
http://mindprod.com

Responsible Development is the style of development I aspire to now. It can be summarized by answering the question, “How would I develop if it were my money?” I’m amazed how many theoretical arguments evaporate when faced with this question.
~ Kent Beck (born: 1961 age: 49) , evangelist for extreme programming.

 

[Arne Vajhøj]

InetAddress.isReachable always returns false. I am puzzled why.

My router is set to pass UDP port 7 through. I can ping google.ca.

Most *nix implementation use ICMP (ping).

The windows version is said to use TCP to port 7 (echo).

Arne

 

[Roedy Green]

I was using 10 seconds. I'll try bumping up the TTL.

no joy.
--
Roedy Green Canadian Mind Products
http://mindprod.com

Responsible Development is the style of development I aspire to now. It can be summarized by answering the question, “How would I develop if it were my money?” I’m amazed how many theoretical arguments evaporate when faced with this question.
~ Kent Beck (born: 1961 age: 49) , evangelist for extreme programming.

 

[Arne Vajhøj]

no joy.

No surprise.

Assuming that you are using Windows, then you are
trying to use TCP through a router
where you have opened for UDP to a site that you
know supports ICMP.

Arne

 

[EJP]

InetAddress.isReachable always returns false. I am puzzled why.

My router is set to pass UDP port 7 through. I can ping google.ca.

InetAddress.isReachable uses *TCP* port 7.

 

[Roedy Green]

InetAddress.isReachable uses *TCP* port 7.

I have them both open. Still no joy.

 

[David Zimmerman]

> Roedy Green Canadian Mind Products
> http://mindprod.com

> If you tell a computer the same fact in more than one place, unless
> you have an automated mechanism to ensure they stay in sync,
> the versions of the fact will eventually get out of sync.

I phrase that as

Anything you write down in more than place,
is wrong in more than one place

 

[Arne Vajhøj]

I have them both open. Still no joy.

It appears that google.ca is not listening on port 7, so
no surprise in that.

Arne

 

[Roedy Green]

I phrase that as

Anything you write down in more than place,
is wrong in more than one place

That's a little strong. Usually one of the places is correct. Usually
the problem does not show up immediately. I applaud your efforts
toward creating an aphorism.