[nos-bbs] UDP Port Unreachable - problem found
Bob Tenty
bobtenty at gmail.com
Sun Nov 17 19:31:19 EST 2013
It doesn't matter or it is 44 addresses but encapsulation or better a
VPN is a way out of the problems you have.
I have dealt with firewalls you have and much worse and always could
find solution for an AXIP
or AXUDP.
Then there is OpenVPN what especially can deal with changing source
ports if you use it in the client - server
configuration.
B
On 13-11-17 11:05 AM, Michael E. Fox - N6MEF wrote:
>
> As I already mentioned: the other end is not running AMPRnet so this
> is straight NAT to the Internet, no encap.
>
>
>
> M
>
>
>
> *From:*nos-bbs-bounces at tapr.org [mailto:nos-bbs-bounces at tapr.org] *On
> Behalf Of *Bob Tenty
> *Sent:* Saturday, November 16, 2013 10:33 PM
> *To:* nos-bbs at tapr.org
> *Subject:* Re: [nos-bbs] UDP Port Unreachable - problem found
>
>
>
> Yes but I mean it in the context that you encapsulate the relevant 44
> addresses at both sides.
> (in the local lan addresses).
>
>
> Bob VE3TOK
>
> On 13-11-17 12:08 AM, Michael E Fox - N6MEF wrote:
>
> We are. But the addresses don't matter since both ends are behind
> a firewall. The addresses could be anything and the problem would
> be the same.
>
>
>
> Michael
>
> N6MEF
>
>
>
>
>
>
>
> Sent from my Verizon Wireless 4G LTE smartphone
>
>
>
> -------- Original message --------
> From: Bob Tenty
> Date:11/16/2013 8:44 PM (GMT-08:00)
> To: nos-bbs at tapr.org <mailto:nos-bbs at tapr.org>
> Subject: Re: [nos-bbs] UDP Port Unreachable - problem found
>
> I don't believe you mentioned about two jnos systems behind the
> same firewall but may be I missed it.
>
> Why are you not using 44 addresses in your axudp link at both
> sides?
>
> Bob
>
>
> On 13-11-16 09:20 PM, Michael E Fox - N6MEF wrote:
>
> No Bob, I'm talking about two JNOS systems behind the same
> firewall. The firewall has to change the source port of at
> least the second one on the way out. Otherwise, the
> destination IP and destination port are all the same on the
> way back in. I believe I've already mentioned this a couple
> of times. This is basic firewall connection muxing.
>
>
>
> Sonicwall happens to change the source port all the time,
> instead of after the first connection. And it works just fine
> for everything but JNOS. If JNOS behaved like a normal UDP
> app, it would work fine, too.
>
>
>
> The point is that there is simply no reason to require a
> specific source port. It's just not the way the UDP world
> works. And doing so renders the system unworkable when placed
> behind 10s of 1000s of commercial firewalls.
>
>
>
> The whole point of axudp is so it can be used in situations
> where axip can't be used. But with this bizarre restriction,
> it's defeating that purpose.
>
>
>
> M
>
>
>
>
>
>
>
>
>
> Sent from my Verizon Wireless 4G LTE smartphone
>
>
>
> -------- Original message --------
> From: Bob Tenty
> Date:11/16/2013 3:38 PM (GMT-08:00)
> To: TAPR xNOS Mailing List
> Subject: Re: [nos-bbs] UDP Port Unreachable - problem found
>
> Michael,
>
> You are making a thinking error here.
>
> If I make a link to another jnos system the destination ip
> number is different.
> Also the return route from that second jnos system uses
> another ip number as the first jnos system so there is no
> problem it all.
> Even with the same port. It is the combination of ip number +
> port.
>
> Those consumer router/firewall boxes are cheaply designed and
> targeted for the average Joe customer user needs.
> Install dd-wrt in it if available for it and you will be much
> happier.
>
>
> 73,
>
> Bob VE3TOK
>
>
>
>
>
>
> On 13-11-16 12:35 PM, Michael E. Fox - N6MEF wrote:
>
> Yes, Linux leaves the source port alone on the first
> connection. But that only works for the first JNOS
> system. Even a firewall that initially leave the source
> port alone will need to change the source port if a second
> JNOS system exists so it can track connections to two
> different machines.
>
>
>
> M
>
>
>
> *From:*nos-bbs-bounces at tapr.org
> <mailto:nos-bbs-bounces at tapr.org>
> [mailto:nos-bbs-bounces at tapr.org] *On Behalf Of *Bob Tenty
> *Sent:* Friday, November 15, 2013 11:37 PM
> *To:* TAPR xNOS Mailing List
> *Subject:* Re: [nos-bbs] UDP Port Unreachable - problem found
>
>
>
> Yes, I have seen that with those boxes. That is why I
> always replace the firmware with linux when possible.
>
> Bob
>
>
> On 13-11-16 01:33 AM, Michael E. Fox - N6MEF wrote:
>
> I found the problem with the UDP port 93 unreachable
> message: JNOS is (incorrectly) requiring the source
> port to also be 93 in AXUDP connections.
>
>
>
> When I connect outbound from my JNOS system, through
> my firewall, the firewall is changing the source port
> when it performs the outbound NAT. But this is normal
> for a firewall. In fact, it HAS to do this if it's
> going to allow for multiple connects of the same
> protocol from different machines. Many consumer-grade
> firewalls will leave the source port alone for the
> first connection (if it's not already in use) and only
> change it for subsequent connections. SonicWall is a
> bit more strict, frequently changing the source port,
> making it harder for intercepted packets to be tracked
> to any one machine.
>
>
>
> Normally, this doesn't matter. Applications/services
> listen on a particular port and respond to whatever
> incoming connections use that **destination** port.
> They don't care what the source port is. Firewalls
> then use different source ports to track multiple
> conversations so that when the packets return, all
> addressed to the same external NAT address, it can
> direct them to the proper place by the port number.
>
>
>
> But when JNOS receives an AXUDP packet, apparently it
> doesn't behave like a normal UDP application. JNOS
> apparently rejects the connection if the **source**
> port is not 93, even if the destination port is
> correctly set to 93. This is unusual, to say the
> least. But even worse, it issues an ICMP "udp port 93
> unreachable" message which is completely wrong, since
> port 93 is definitely reachable.
>
>
>
> It seems the following is needed: Remove the source
> port restriction for AXUDP. JNOS should not care what
> the source port is. And, just like any other UDP app,
> when responding it should use whatever source port was
> specified as the destination port when it constructs
> the return packet.
>
>
>
> Michael
>
> N6MEF
>
>
>
>
>
>
>
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