error: cannot find PDP context for incoming packet for IP

[r00tb3]

Hey all, I'm not able to connect to GPRS on my OpenBTS setup. I'm stuck at the following error can anyone pls guide me?

 15:32:42.9:  GGSN.IP.TossDuplicatePackets=0
 15:32:42.9:GGSN: DNS servers: 8.8.8.8 0.0.0.0
 15:32:42.9:ip link set sgsntun up 
 15:32:43.1:ip route add to 192.168.99.0/24 dev sgsntun 
 15:32:43.4:ggsn: received proto=128 48 byte packet from 0.0.0.0 to 109.223.105.98 at  15:32:43.4
 15:32:43.4:ggsn: error: cannot find PDP context for incoming packet for IP dstaddr=109.223.XX.XX
 15:32:47.0:ggsn: received proto=128 48 byte packet from 0.0.0.0 to 109.223.XX.XX at  15:32:47.0
 15:32:47.0:ggsn: error: cannot find PDP context for incoming packet for IP dstaddr=109.223.XX.XX
 15:32:51.1:ggsn: received proto=128 48 byte packet from 0.0.0.0 to 109.223.XX.XX at  15:32:51.1
 15:32:51.1:ggsn: error: cannot find PDP context for incoming packet for IP dstaddr=109.223.XX.XX

Is the device not able to communicate through sgsntun interface?

Are the ggsn/sgsn settings messed up?

I haven't plugged in any Ethernet cable to my laptop only connected to Wi-Fi.

Regards.

[blinkomaniak]

Hi there, can you please execute "audit" on OpenBTS CLI and post it here (it is better than sharing the all config). Also describe your setup (PC, SDR, phone), distance from the phone to SDR, then I will look into "power" and "rxgain" parameters..., also ... before initializing OpenBTS, have you executed any command related with "iptables"?

Regards

[r00tb3]

@blinkomaniak audit log:

OpenBTS> audit
+---------------------------------------------------------------------+
| ERROR : Invalid Values [key current-value (default)]                |
|   To use the default value again, execute: rmconfig key             |
+---------------------------------------------------------------------+
Control.LUR.FailMode "ACCEPT" ("ACCEPT")
GSM.CCCH.BS_AG_BLKS_RES "auto" ("auto")
GSM.CCCH.BS_PA_MFRMS "2" ("2")
GSM.CallerID.Source "auto" ("auto")
NodeManager.API.PhysicalStatus "disabled" ("disabled")
SMS.MIMEType "application/vnd.3gpp.sms" ("application/vnd.3gpp.sms")

+---------------------------------------------------------------------+
| WARNING : Site Values Which Are Still Default [key current-value]   |
|   These should be set to fit your installation: config key value    |
+---------------------------------------------------------------------+
GSM.Identity.BSIC.BCC "2"
GSM.Identity.BSIC.NCC "0"
GSM.Identity.CI "10"
GSM.Identity.LAC "1000"
GSM.Identity.MCC "001"
GSM.Identity.MNC "01"
GSM.Radio.C0 "51"

+---------------------------------------------------------------------+
| INFO : Non-Default Values [key current-value (default)]             |
|   To use the default value again, execute: rmconfig key             |
+---------------------------------------------------------------------+
Control.GSMTAP.GPRS "1" ("0")
Control.LUR.NormalRegistration.Message "Welcome to the STAI network" ("")
Control.LUR.OpenRegistration ".*" ("")
Control.LUR.OpenRegistration.Message "Your IMSI is:" ("Welcome to the test network.  Your IMSI is ")
GGSN.DNS "1.1.1.1" ("")
GGSN.Firewall.Enable "0" ("1")
GGSN.Logfile.Name "/tmp/GGSN.log" ("")
GPRS.ChannelCodingControl.RSSI "-65" ("-40")
GPRS.Channels.Min.C0 "7" ("2")
GPRS.Enable "1" ("0")
GPRS.Multislot.Max.Downlink "5" ("3")
GPRS.Multislot.Max.Uplink "3" ("2")
GSM.Radio.PowerManager.MaxAttenDB "0" ("10")
GSM.Radio.RSSITarget "-75" ("-50")
GSM.Radio.RxGain "10" ("47")
Log.Level "DEBUG" ("NOTICE")
TRX.MinimumRxRSSI "-63" ("-90")

+---------------------------------------------------------------------+
| INFO : Custom/Deprecated Key/Value Pairs [key current-value]        |
|   To clean up any extraneous keys, execute: rmconfig key            |
+---------------------------------------------------------------------+
GSM.ChangeMark "11"
TRX.Reference "internal"

I'm using a think-pad based on i7, Ubuntu 16.04, USRP B200 and OpenBTS the MS is inside the faraday cage placed close to the USRP B200.

Power:

OpenBTS> power
current downlink power 0 dB wrt full scale

RxGain:

GSM.Radio.RxGain "10" ("47")

Before initializing OpenBTS, have you executed any command related with "iptables":

sudo iptables-restore < /etc/OpenBTS/iptables.rules

I'm still stuck on this issue.

Pls, help I don't understand what I'm missing.

Regards.

[r00tb3]

Fixed the issue.

I had no Ethernet connectivity changed the interface to WiFi in iptables.

One of the devices i was using using had a carrier's SIM which was programmed for DCS 1800 so had to tweak OpenBTS for the same config.