From owner-freebsd-net@FreeBSD.ORG  Tue May  7 18:43:59 2013
Return-Path: <owner-freebsd-net@FreeBSD.ORG>
Delivered-To: freebsd-net@freebsd.org
Received: from mx1.freebsd.org (mx1.freebsd.org
 [IPv6:2001:1900:2254:206a::19:1])
 by hub.freebsd.org (Postfix) with ESMTP id 0422DED1
 for <freebsd-net@freebsd.org>; Tue,  7 May 2013 18:43:59 +0000 (UTC)
 (envelope-from lists@rewt.org.uk)
Received: from hosted.mx.as41113.net (hosted.mx.as41113.net [91.208.177.22])
 by mx1.freebsd.org (Postfix) with ESMTP id C50F4AE1
 for <freebsd-net@freebsd.org>; Tue,  7 May 2013 18:43:58 +0000 (UTC)
Received: from [172.16.9.23] (bella.stf.rewt.org.uk [91.208.177.62])
 (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits))
 (No client certificate requested)
 (Authenticated sender: lists@rewt.org.uk)
 by hosted.mx.as41113.net (Postfix) with ESMTPSA id 3b4qTf6K9yzYx;
 Tue,  7 May 2013 19:43:50 +0100 (BST)
Message-ID: <51894B52.2050903@rewt.org.uk>
Date: Tue, 07 May 2013 19:43:30 +0100
From: Joe Holden <lists@rewt.org.uk>
User-Agent: Thunderbird 2.0.0.24 (Windows/20100228)
MIME-Version: 1.0
To: Matthias Apitz <guru@unixarea.de>
Subject: Re: ppp(8) and inbound IP connections
References: <20130507181345.GA992@tiny.Sisis.de>
In-Reply-To: <20130507181345.GA992@tiny.Sisis.de>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
Content-Transfer-Encoding: 7bit
Cc: freebsd-net@freebsd.org
X-BeenThere: freebsd-net@freebsd.org
X-Mailman-Version: 2.1.14
Precedence: list
List-Id: Networking and TCP/IP with FreeBSD <freebsd-net.freebsd.org>
List-Unsubscribe: <http://lists.freebsd.org/mailman/options/freebsd-net>,
 <mailto:freebsd-net-request@freebsd.org?subject=unsubscribe>
List-Archive: <http://lists.freebsd.org/pipermail/freebsd-net>
List-Post: <mailto:freebsd-net@freebsd.org>
List-Help: <mailto:freebsd-net-request@freebsd.org?subject=help>
List-Subscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-net>,
 <mailto:freebsd-net-request@freebsd.org?subject=subscribe>
X-List-Received-Date: Tue, 07 May 2013 18:43:59 -0000

Matthias Apitz wrote:
> 
> Hello,
> 
> I'm using ppp(8) for many years to connect via UMTS to my service provider
> and Internet, actually www.fonic.de; all this works fine already for long
> time, works fine for outgoing TCP and UDP connections to Internet.
> 
> Until now, I did not care about incoming TCP connections, for example for
> SSH'ing from remote to my netbook, connected via ppp(8), or for incoming
> SIP; it turns out now,, that I can:
> 
> - check with "lynx -dump myip.nl | fgrep WAN" with which addr I show
>   up in Internet:
> 
>   $ lynx -dump myip.nl | fgrep WAN
>           WAN IP adres: 82.113.99.104
> 
> - can SSH fine to some remote server, 
> 
> - but can not SSH back to the addr 82.113.99.104;
> 
> I contacted the provider thinking that he is blocking all IP connects which
> have not been originated by a SYN pkg from my side; but he claims not
> blocking anything; and now? how can I debug this?
> 
> My interface looks like this:
> 
> 
> tun6: flags=8051<UP,POINTOPOINT,RUNNING,MULTICAST> metric 0 mtu 1500
> 	options=80000<LINKSTATE>
> 	inet 10.33.28.104 --> 10.64.64.64 netmask 0xffffffff 
> 	nd6 options=21<PERFORMNUD,AUTO_LINKLOCAL>
> 	Opened by PID 799
> 
> and the routing is:
> 
> 
> Routing tables
> 
> Internet:
> Destination        Gateway            Flags    Refs      Use  Netif Expire
> default            10.64.64.64        UGS         0     1694   tun6
> 10.33.28.104       link#7             UHS         0        0    lo0
> 10.64.64.64        link#7             UHS         0        1   tun6
> 127.0.0.1          link#6             UH          0       75    lo0
> 
> Any ideas about this? Thanks.
> 
> I'm attaching the ppp.conf file.
> 
> 	matthias
> 
It seems quite clear from your ifconfig output that your provider 
doesn't give you a routable address, so you will never see inbound 
connections.  Usually providers have an alternate APN that will give you 
one, but that depends on the provider in question.