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DoS protection: Not accepting more calls


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Posted

Hi,

 

Our customer is using snomONE version 4.2.0.3958 (Linux)and everthing was working fine. Today they are unable to call between the extensions. The snom phone displays the message as "Temporarily unavailable". In the PBX logs we see "DoS protection: Not accepting more calls"

 

Let me know how we can fix this problem. We are using version 4.2.0.3958 (Linux.

 

Regards

Ganesh

Posted

Well, that means that there are too many calls within a short time. You can increase the value of max_udp_invite or use TCP for SIP.

 

Thanks. Let me know how we can increase this value (max_udp_invite). Is this value in the snomONE configuration settings?

 

Regards,

Ganesh

  • 2 years later...
Posted

I run into the same error with a PBX which (so far) was basically idle: just 3 phones plus one firewalled SIP trunk. So there really, really are not too many calls and no malicious IP is involved.

 

What are the expected default values for this max_udp_invite?

Posted

The max_udp_invite setting is limiting how many requests the system accepts per second on UDP transport layer. This is simply about situations when the system gets flooded with INVITE requests.

 

There are other settings how many calls you can have per system, or domain and even per extension. The log should show you why ca call gets rejected.

Posted

For the record: as the PBX was up for ~9 months, I simple restarted it. This cleared the issue.

 

The log was not really helpful in this case, see:

[8] 20140722141631: HTTP/NTP/SNMP client waited for 60 s
[5] 20140722141657: Identify trunk (IP address/port and domain match) 4
[5] 20140722141837: Last message repeated 4 times
[3] 20140722141837: DoS protection: Not accepting more calls
[5] 20140722141857: Identify trunk (IP address/port and domain match) 4
[8] 20140722141927: Trunk 4: Preparing for re-registration
[8] 20140722141927: Trunk xxx: Sending registration to xxx.xx
[8] 20140722141927: Answer challenge with username xxx
[8] 20140722141927: Trunk 4: setup callback to send re-registration after 240 seconds
[5] 20140722141927: Identify trunk (IP address/port and domain match) 4

Posted

Is the PBX running on public IP (exposed to scanners)? In that case you could really experience the DoS protection. Even after 9 months it should not deteriorate. For the record, which version is this?

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