Question about establishing an internet connection between MS and network core

morteza ali Ahmadi morteza.ali.ahmadi at
Thu Jan 21 07:57:49 UTC 2021

Hi Osmocom team.
We are sorry to disturb you.
We have a question about establishing a stable internet connection
(IuPS_PS) between MS and our developed network core system using our home
nodeB (HNB).
We set *Primary DNS Address: *(core IP) and *Secondary DNS
Address:* in *Activate PDP Context Accept.*
At this step, we can see the MS packets in the interface between HNB and
core using wireshark. The protocol is *GTP <DNS>* and the stacked layers
are *DNS / UDP / IP / GTP / UDP / IP* which I attached a screenshot of the
wireshark log.
As you can see in the attached image, our query in the MS is
*server.hnb* *(http://server.hnb
<http://server.hnb>)*. In order to show our default page to the user query,
we set up a DNS server and HTTP server (Apache) in and *BIND9*
is configured as the primary server for the domain *server.hnb*. The
command *dig @localhost server.hnb* outputs the following:

; <<>> DiG 9.16.1-Ubuntu <<>> @localhost server.hnb
; (1 server found)
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 49532
;; flags: qr aa rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 1

; EDNS: version: 0, flags:; udp: 4096
; COOKIE: 15821f64047895870100000060070fb921a17af91fd22f9f (good)
;server.hnb. IN A

server.hnb. 604800 IN A

;; Query time: 0 msec
;; WHEN: Jan 19 20:28:33 +0330 2021
;; MSG SIZE  rcvd: 83

and also when we query *http://server.hnb <http://server.hnb> *in the
browser of the core system (, we see the * Apache2 Ubuntu
Default Page* but this default page is not shown in the MS.
Furthermore, we think that a GTP tunnel may be required and we set up a GTP
tunnel using *libgtpnl* and the two following commands:

gtp-link add gtp1
gtp-tunnel add gtp1 v1 1 100

where 1 is the gTP-TEI obtained in *RAB-Assignment Response *and 100 is the
similar field in *RAB-Assignment Request. *Also, is the MS IP
and is the core IP. But there is no captured package in this
tunnel (using wireshark).

Could you please help us to solve this problem which is mentioned in the
following questions?
Is the above procedure performed in the correct way?
We want to show our default page in MS when the user query is*
http://server.hnb <http://server.hnb>*, but we think that a GTP manager is
required to split the (( DNS / UDP / IP )) layers from (( DNS / UDP / IP /
GTP / UDP / IP )) to send to DNS server. How can it be solved, if this
assumption is correct?

Thank you again for spending time with us.
Best regards,
Morteza Ali Ahmadi

*When there is much light, The shadow is deep...*
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