Is it possible, bind has done but the OS still respond with ICMP destination unreachable

Is it possible, bind has done but the OS still respond with ICMP destination unreachable

Post by Bin Che » Wed, 28 Mar 2007 11:20:08



Hi,

I encounter a problem seems strange. I ran ser(a open source SIP
server) which binds to the port 5060. After the system starting up, I
can see aparently that the ser has successfully bind to UDP 5060. But
when other machine send packets to 5060(UDP), the OS responds it with
ICMP error(destination unreachable, port unreachable), any other
possibilities will cause this?

I am using ubuntu 6.10.

Thanks in advance.

abai

 
 
 

Is it possible, bind has done but the OS still respond with ICMP destination unreachable

Post by Bin Che » Wed, 28 Mar 2007 11:32:14



Quote:> Hi,

> I encounter a problem seems strange. I ran ser(a open source SIP
> server) which binds to the port 5060. After the system starting up, I
> can see aparently that the ser has successfully bind to UDP 5060. But
> when other machine send packets to 5060(UDP), the OS responds it with
> ICMP error(destination unreachable, port unreachable), any other
> possibilities will cause this?

> I am using ubuntu 6.10.

> Thanks in advance.

> abai

If a program first does a bind, and then it enter a dead loop, will
the OS find  the binder has dead and respond a ICMP error?

 
 
 

Is it possible, bind has done but the OS still respond with ICMP destination unreachable

Post by Allen McIntos » Thu, 29 Mar 2007 10:18:33


Quote:> I encounter a problem seems strange. I ran ser(a open source SIP
> server) which binds to the port 5060. After the system starting up, I
> can see aparently that the ser has successfully bind to UDP 5060.

You shouldn't be saying "apparently".  Run netstat -ltu and see what it
*has* bound to.
 
 
 

Is it possible, bind has done but the OS still respond with ICMP destination unreachable

Post by Bin Che » Fri, 30 Mar 2007 21:11:40



Quote:> > I encounter a problem seems strange. I ran ser(a open source SIP
> > server) which binds to the port 5060. After the system starting up, I
> > can see aparently that the ser has successfully bind to UDP 5060.

> You shouldn't be saying "apparently".  Run netstat -ltu and see what it
> *has* bound to.

Sure, I have checked this and see the binding.
 
 
 

1. ICMP Destination Unreachable (Host Unreachable) [**] [Solved!!!]

Hello to you all.

I had some problems with the IDS alerts in snort regarding the subject
of this post.

 ICMP Destination Unreachable (Host Unreachable) [**]

Well, it seems to be solved here, and I did solve it like this.

1. go to your adsl/router
2. fill in dns properties from your dhcp dns server the correct dns
domain name of your host.
3. save this configuration.

And you are not longer troubled with the ICMP unreachable host
messages.

It is finally a bit quiet in te logs, and also the spp portscan
activities are gone.

Still I am curious how this exactly works, and if my solution helped
some of you, and if it is a correct solution I have applied???

Because maybe I am introducing a security related flaw, what I don't
like ofcourse, because maybe it was alright that the Snort IDS was
generating these alerts.

Well, I hope some of you will send a reply to me with some
backgrounds, and some advice if neccesary.

Just send a copy to my e-mail address if it helped you, or you have
something to say about this post.

Have a nice day you all!

Wouter Jan Wessels.

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