Questions[gprs](server)

I'm increasingly seeing mobile networking technologies being used to get internet access in areas where it is otherwise not available.

While mobile networking is usually not yet viable as the primary internet connection, mobile technology looks like a good option for an emergency fallback.

Bandwith is not the problem: With HDSPA, speeds of several MBit are possible, which provides a decent uplink. However, I know from personal experience that mobile networks internet links (via GPRS, UMTS etc.) have much higher latencies than regular DSL (200-400 ms for UMTS, even more for GPRS). This of course makes them unsuitable for many applications, such as VoIP and teleconferencing.

• Where does this latency come from?
• Are there any technologies available that can mitigate this problem, to make UMTS viable for low-latency applications?

I assume there must be some inherent technical reason, but what is it? Does it have to do with how data is transmitted over the air? And if it is because of the wireless transmission, why does WLAN have much lower latencies?

Noobish question -

I have a perl script running on a linux server which opens UDP port 7015. netstat -ulnp shows:

udp        0      0 0.0.0.0:7015                0.0.0.0:*                               16365/perl

nmap -sU -p 7015 'hostname' on a remote machine shows:

7015/udp open|filtered unknown

Now when I run a client java program on an Android device, and send a datagram, it works flawlessly under wifi, but not through the cell network - after wifi is turned off or the device is moved out of wifi range. Other than possible port-blocking by the provider, why would this socket work under wifi, but not GPRS?

I'm having trouble making a ppp connection over a GSM Modem. The Platform is an ARM based embedded device, running Debian Linux 5. The scripts worked before with this device, but not with the new shipment. I just can't get enough information out of chat (/usr/sbin/chat).

The connection is started out of a C Program and the call looks something like this:

/usr/sbin/pppd ttyS1 connect /usr/sbin/chat -S -s -v -T PIN-Nr -f /etc/chatscripts/chat_gprs_con

I have tracked the Problem down to chat, which handles the communication with the modem hardware.

/usr/sbin/chat -e -v -T PIN-NR -f /etc/chatscripts/chat_gprs_con

chat_gprs_con looks like this:

TIMEOUT         10
ECHO            ON
ABORT           '\nBUSY\r'
ABORT           '\nERROR\r'
ABORT           '\nNO ANSWER\r'
ABORT           '\nNO CARRIER\r'
ABORT           '\nNO DIALTONE\r'
ABORT           '\RINGRING\r\n\r\nRINGRING\r'
""      AT
'OK-\d+++\d\d\c-OK'     ATZ
TIMEOUT         3
OK      AT+CSQ
OK      ATE1
OK      AT+CPIN?
'CPIN: READY-AT+CPIN="\T"-OK'   'AT+COPS?'
OK              'at+cgdcont=1, "IP", "a1.net"'
OK              ATD*99***1#
TIMEOUT         25
SAY     "\nwaiting for connect...\n"
CONNECT         ""
SAY     "\nConnected."
SAY     "\nIf the following ppp negotiations fail,\n"
SAY     "try restarting the phone.\n"

The only info I get throug the verbose output in /var/log/syslog or /var/log/messages is:

Jan  1 00:12:30 evm chat[1405]: timeout set to 10 seconds
Jan  1 00:12:30 evm chat[1405]: abort on (\nBUSY\r)
Jan  1 00:12:30 evm chat[1405]: abort on (\nERROR\r)
Jan  1 00:12:30 evm chat[1405]: abort on (\nNO ANSWER\r)
Jan  1 00:12:30 evm chat[1405]: abort on (\nNO CARRIER\r)
Jan  1 00:12:30 evm chat[1405]: abort on (\nNO DIALTONE\r)
Jan  1 00:12:30 evm chat[1405]: abort on (\RINGRING\r\n\r\nRINGRING\r)
Jan  1 00:12:30 evm chat[1405]: send (AT^M)
Jan  1 00:12:30 evm chat[1405]: expect (OK)
Jan  1 00:12:40 evm chat[1405]: alarm
Jan  1 00:12:40 evm chat[1405]: send (\d+++\d\d)
Jan  1 00:12:43 evm chat[1405]: expect (OK)
Jan  1 00:12:53 evm chat[1405]: alarm
Jan  1 00:12:53 evm chat[1405]: Failed

But I can't find out WHY it fails :(

Any ideas and help are very apprechiated! Thanks, Ben

I'm setting up an IPSec connection from an Westermo MRD310 to our company Cisco ASA5510.

We've had many successful setups using this method, creating a tunnel network between a remote location and our internal network. This time I'm trying to do this setup over a GPRS speed network (that's what you get way up in the north of Sweden). But it won't go through.

Does anyone have information about what fails in the following log, or have information about minimum transfer rates for establishing an IPSec tunnel. Also, any information on what could decrease transfer rate requirements would be appreciated.

I use a subscription with public, static IP-address to avoid NAT:ing and unexpected address changes. However as the GPRS is the initiator, static IP shouldn't be a requirement for this, am I right?

<83>Jun 21 23:00:57 ipsec__plutorun: Starting Pluto subsystem...  
<27>Jun 21 23:00:57 ipsec_setup: ...Openswan IPsec started  
<84>Jun 21 23:00:57 pluto[5860]: Starting Pluto (Openswan Version 2.4.12 PLUTO_SENDS_VENDORID PLUTO_USES_KEYRR; Vendor ID OEKBzdY{wM]@) 
<84>Jun 21 23:00:57 pluto[5860]: Setting NAT-Traversal port-4500 floating to on 
<84>Jun 21 23:00:57 pluto[5860]:    port floating activation criteria nat_t=1/port_fload=1 
<84>Jun 21 23:00:57 pluto[5860]:   including NAT-Traversal patch (Version 0.6c) 
<86>Jun 21 23:00:57 ipsec__plutorun: Unknown default RSA hostkey scheme, not generating a default hostkey 
<84>Jun 21 23:00:57 pluto[5860]: ike_alg_register_enc(): Activating OAKLEY_AES_CBC: Ok (ret=0) 
<84>Jun 21 23:00:57 pluto[5860]: no helpers will be started, all cryptographic operations will be done inline 
<84>Jun 21 23:00:57 pluto[5860]: Using KLIPS IPsec interface code on 2.6.25-uc0 
<84>Jun 21 23:00:57 pluto[5860]: Changing to directory '/etc/config/cacerts' 
<84>Jun 21 23:00:57 pluto[5860]: Changing to directory '/etc/config/aacerts' 
<84>Jun 21 23:00:57 pluto[5860]: Changing to directory '/etc/config/ocspcerts' 
<84>Jun 21 23:00:57 pluto[5860]: Changing to directory '/etc/config/crls' 
<84>Jun 21 23:00:57 pluto[5860]:   Warning: empty directory 
<27>Jun 21 23:00:57 ipsec_setup: Starting Openswan IPsec 2.4.12...  
<84>Jun 21 23:00:58 pluto[5860]: loading secrets from "/etc/config/ipsec.secrets" 
<84>Jun 21 23:01:01 pluto[5860]: added connection description "SPMVPN" 
<84>Jun 21 23:01:01 pluto[5860]: listening for IKE messages 
<84>Jun 21 23:01:01 pluto[5860]: adding interface ipsec0/hso0 85.117.XXX.XX:500 
<84>Jun 21 23:01:01 pluto[5860]: adding interface ipsec0/hso0 85.117.XXX.XX:4500 
<84>Jun 21 23:01:01 pluto[5860]: forgetting secrets 
<84>Jun 21 23:01:01 pluto[5860]: loading secrets from "/etc/config/ipsec.secrets" 
<84>Jun 21 23:01:02 pluto[5860]: "SPMVPN" #1: initiating Main Mode 
<27>Jun 21 23:01:02 ipsec__plutorun: 104 "SPMVPN" #1: STATE_MAIN_I1: initiate  
<27>Jun 21 23:01:02 ipsec__plutorun: ...could not start conn "SPMVPN"  
<84>Jun 21 23:01:02 pluto[5860]: "SPMVPN" #1: received Vendor ID payload [draft-ietf-ipsec-nat-t-ike-02_n] method set to=106  
<84>Jun 21 23:01:02 pluto[5860]: "SPMVPN" #1: ignoring Vendor ID payload [FRAGMENTATION c0000000] 
<84>Jun 21 23:01:02 pluto[5860]: "SPMVPN" #1: enabling possible NAT-traversal with method draft-ietf-ipsec-nat-t-ike-02/03 
<84>Jun 21 23:01:02 pluto[5860]: "SPMVPN" #1: transition from state STATE_MAIN_I1 to state STATE_MAIN_I2 
<84>Jun 21 23:01:02 pluto[5860]: "SPMVPN" #1: STATE_MAIN_I2: sent MI2, expecting MR2 
<84>Jun 21 23:01:13 pluto[5860]: "SPMVPN" #1: ignoring informational payload, type INVALID_COOKIE 
<84>Jun 21 23:01:13 pluto[5860]: "SPMVPN" #1: received and ignored informational message 
<84>Jun 21 23:01:32 pluto[5860]: "SPMVPN" #1: ignoring informational payload, type INVALID_COOKIE 
<84>Jun 21 23:01:32 pluto[5860]: "SPMVPN" #1: received and ignored informational message 
<84>Jun 21 23:02:12 pluto[5860]: "SPMVPN" #1: max number of retransmissions (2) reached STATE_MAIN_I2 
<84>Jun 21 23:02:12 pluto[5860]: "SPMVPN" #1: starting keying attempt 2 of an unlimited number 
<84>Jun 21 23:02:12 pluto[5860]: "SPMVPN" #2: initiating Main Mode to replace #1 
<84>Jun 21 23:02:12 pluto[5860]: "SPMVPN" #2: received Vendor ID payload [draft-ietf-ipsec-nat-t-ike-02_n] method set to=106  
<84>Jun 21 23:02:12 pluto[5860]: "SPMVPN" #2: ignoring Vendor ID payload [FRAGMENTATION c0000000] 
<84>Jun 21 23:02:12 pluto[5860]: "SPMVPN" #2: enabling possible NAT-traversal with method draft-ietf-ipsec-nat-t-ike-02/03 
<84>Jun 21 23:02:12 pluto[5860]: "SPMVPN" #2: transition from state STATE_MAIN_I1 to state STATE_MAIN_I2 
<84>Jun 21 23:02:12 pluto[5860]: "SPMVPN" #2: STATE_MAIN_I2: sent MI2, expecting MR2 
<84>Jun 21 23:02:22 pluto[5860]: "SPMVPN" #2: ignoring informational payload, type INVALID_COOKIE 
<84>Jun 21 23:02:22 pluto[5860]: "SPMVPN" #2: received and ignored informational message 
<84>Jun 21 23:02:42 pluto[5860]: "SPMVPN" #2: ignoring informational payload, type INVALID_COOKIE 
<84>Jun 21 23:02:42 pluto[5860]: "SPMVPN" #2: received and ignored informational message 

Let's assume we have two Windows XP computers with identical hardware configuration, including GPRS modem connected to COM1 serial port. On the first PC we add new modem device, set up gprs connection on this port in "Network connections" folder. How avoid clicking the same procedure on second computer?

Detailed questions:

1. Where are the entries from "Network connections" stored? File, registry? Is there a possibility to clone such entry between PCs?
2. Question as above but regarding modem entry in device manager - can it be exported from one pc and imported on second?