TDoS Attack Mitigation

The TDoS Attack Mitigation feature enables Cisco Unified Border Element (Cisco UBE) to not respond to Session Initiation Protocol (SIP) requests from IP addresses that are not listed in a trusted IP address list. Cisco UBE validates only out-of-dialog SIP requests against IP addresses in the trusted IP address list. It does not validate in-dialog SIP requests because such requests usually arrive from trusted entities. The TDoS Attack Mitigation feature is supported both on IPv4 and IPv6 networks.

Finding Feature Information

Your software release may not support all the features documented in this module. For the latest caveats and feature information, see Bug Search Tool and the release notes for your platform and software release. To find information about the features documented in this module, and to see a list of the releases in which each feature is supported, see the feature information table.

Use Cisco Feature Navigator to find information about platform support and Cisco software image support. To access Cisco Feature Navigator, go to www.cisco.com/​go/​cfn. An account on Cisco.com is not required.

Information About TDoS Attack Mitigation

The TDoS Attack Mitigation feature prevents Cisco Unified Border Element (Cisco UBE) from responding to Session Initiation Protocol (SIP) requests arriving from untrusted IP addresses, which leads to an improvement in performance. The SIP stack authenticates the source IP address of an incoming SIP request and blocks the response if the source IP address does not match any IP address in the trusted IP address list. To create a trusted IP address list, you may configure a list of IP addresses or use the IP addresses that have been configured using the session target command in dial-peer configuration mode.

Cisco UBE does not respond to REGISTER requests and consumes REGISTER requests if you configure it only for Telephony Denial-of-Service (TDoS) Attack Mitigation and not as a registrar server.

If you configure Cisco UBE as a registrar server for TDoS attack mitigation, it consumes responses for REGISTER requests that do not belong to any application. Cisco UBE does not consume responses to REGISTER requests that belong to a registrar application.


Note

A SIP registrar is a server that accepts REGISTER requests and is typically collocated with a proxy or redirect server.

Syslogs are printed on the device console every 60 minutes after Cisco UBE consumes a threshold value of 1000 SIP requests.

How to Configure TDoS Attack Mitigation

Configuring a Trusted IP Address List for Toll-Fraud Prevention

SUMMARY STEPS

    1.    enable

    2.    configure terminal

    3.    voice service voip

    4.    ip address trusted list

    5.    ipv4 ipv4-address [network-mask]

    6.    ipv6 ipv6-address

    7.    end


DETAILED STEPS
     Command or ActionPurpose
    Step 1 enable


    Example: 
    Device> enable
     

    Enables privileged EXEC mode.

    • Enter your password if prompted.
     
    Step 2 configure terminal


    Example: 
    Device# configure terminal
     

    Enters global configuration mode.

     
    Step 3 voice service voip


    Example: 
    Device(config)# voice service voip
     

    Enters global VoIP configuration mode.

     
    Step 4 ip address trusted list


    Example: 
    Device(conf-voi-serv)# ip address trusted list
     

    Enters IP address trusted list mode and enables the addition of valid IP addresses.

     
    Step 5ipv4 ipv4-address [network-mask]


    Example: 
    Device(cfg-iptrust-list)# ipv4 192.0.2.1 255.255.255.0
     

    Allows you to add up to 100 IPv4 addresses in the IP address trusted list. Duplicate IP addresses are not allowed.

    • The network-mask argument allows you to define a subnet IP address.

     
    Step 6ipv6 ipv6-address


    Example: 
    Device(cfg-iptrust-list)# ipv6 2001:DB8:0:ABCD::1/48
     

    Allows you to add IPv6 addresses to the trusted IP address list.

     
    Step 7end


    Example: 
    Device(cfg-iptrust-list)# end
     

    Returns to privileged EXEC mode.

     

    Configuring TDoS Attack Mitigation

    SUMMARY STEPS

      1.    enable

      2.    configure terminal

      3.    voice service voip

      4.    ip address trusted authenticate

      5.    allow-connections from-type to to-type

      6.    sip

      7.    no registrar server

      8.    silent-discard untrusted

      9.    end

      10.    show sip-ua statistics

      11.    clear sip-ua statistics


    DETAILED STEPS
       Command or ActionPurpose
      Step 1 enable


      Example: 
      Device> enable
       

      Enables privileged EXEC mode.

      • Enter your password if prompted.

       
      Step 2configure terminal


      Example: 
      Device# configure terminal
       

      Enters global configuration mode.

       
      Step 3 voice service voip


      Example: 
      Device(config)# voice service voip
       

      Enters voice service configuration mode.

       
      Step 4ip address trusted authenticate


      Example: 
      Device(conf-voi-serv)# ip address trusted authenticate
       

      Enables IP address authentication on incoming H.323 or Session Initiation Protocol (SIP) trunk calls for toll fraud prevention support.

       
      Step 5allow-connections from-type to to-type


      Example: 
      Device(conf-voi-serv)# allow-connections sip to sip
       

      Allows connections between specific types of endpoints in a Cisco UBE.

       
      Step 6sip


      Example: 
      Device(conf-voi-serv)# sip
       

      Enters SIP configuration mode.

       
      Step 7no registrar server


      Example: 
      Device(conf-serv-sip)# no registrar server
       

      Disables the local SIP registrar.

       
      Step 8silent-discard untrusted


      Example: 
      Device(conf-serv-sip)# silent-discard untrusted
       

      Discards SIP requests from untrusted sources on an incoming SIP trunk.

       
      Step 9end


      Example: 
      Device(conf-serv-sip)# end
       

      Returns to privileged EXEC mode.

       
      Step 10show sip-ua statistics


      Example: 
      Device# show sip-ua statistics
       

      (Optional) Displays response, traffic, and retry SIP statistics.

       
      Step 11clear sip-ua statistics


      Example: 
      Device# clear sip-ua statistics
       

      (Optional) Resets the SIP user agent (UA) statistical counters to zero.

       

      Verifying TDoS Attack Mitigation

      Sample output for the show sip-ua statistics command

      To display response, traffic, and retry Session Initiation Protocol (SIP) statistics, use the show sip-ua statistics command in privileged EXEC mode.

      Device# show sip-ua statistics

SIP Response Statistics (Inbound/Outbound)
    Informational:
      Trying 0/0, Ringing 0/0,
      Forwarded 0/0, Queued 0/0,
      SessionProgress 0/0
    Success:
      OkInvite 0/0, OkBye 0/0,
      OkCancel 0/0, OkOptions 0/0,
      OkPrack 0/0, OkRegister 0/0
      OkSubscribe 0/0, OkNotify 0/0, OkPublish 0/0
      OkInfo 0/0, OkUpdate 0/0,
      202Accepted 0/0, OkOptions 0/0
    Redirection (Inbound only except for MovedTemp(Inbound/Outbound)) :
      MultipleChoice 0, MovedPermanently 0,
      MovedTemporarily 0/0, UseProxy 0,
      AlternateService 0
    Client Error:
      BadRequest 0/0, Unauthorized 0/0,
      PaymentRequired 0/0, Forbidden 0/0,
      NotFound 0/0, MethodNotAllowed 0/0,
      NotAcceptable 0/0, ProxyAuthReqd 0/0,
      ReqTimeout 0/0, Conflict 0/0, Gone 0/0,
      ConditionalRequestFailed 0/0,
      ReqEntityTooLarge 0/0, ReqURITooLarge 0/0,
      UnsupportedMediaType 0/0, UnsupportedURIScheme 0/0,
      BadExtension 0/0, IntervalTooBrief 0/0,
      TempNotAvailable 0/0, CallLegNonExistent 0/0,
      LoopDetected 0/0, TooManyHops 0/0,
      AddrIncomplete 0/0, Ambiguous 0/0,
      BusyHere 0/0, RequestCancel 0/0,
      NotAcceptableMedia 0/0, BadEvent 0/0,
      SETooSmall 0/0, RequestPending 0/0,
      UnsupportedResourcePriority 0/0,
      Total untrusted Request Consumed 1500,//This counter increments (+1) on reception of an untrusted SIP request.//
      Untrusted Request Consumed in last lap 300,//This counter is updated after every 60 minutes.//
      Last Threshold for Untrusted Request Consumed 1000//This counter activates when the router boots up. Counter value is the number of untrusted requests that are consumed (after crossing 1000 SIP requests) in each interval of 60 minutes after the router boots up.//
    Server Error:
      InternalError 0/0, NotImplemented 0/0,
      BadGateway 0/0, ServiceUnavail 0/0,
      GatewayTimeout 0/0, BadSipVer 0/0,
      PreCondFailure 0/0
    Global Failure:
      BusyEverywhere 0/0, Decline 0/0,
      NotExistAnywhere 0/0, NotAcceptable 0/0
    Miscellaneous counters:
      RedirectRspMappedToClientErr 0

SIP Total Traffic Statistics (Inbound/Outbound)
    Invite 0/0, Ack 0/0, Bye 0/0,
    Cancel 0/0, Options 0/0,
    Prack 0/0, Update 0/0,
    Subscribe 0/0, Notify 0/0, Publish 0/0
    Refer 0/0, Info 0/0,
    Register 0/0

Retry Statistics
    Invite 0, Bye 0, Cancel 0, Response 0,
    Prack 0, Reliable1xx 0, Notify 0, Info 0
    Register 0 Subscribe 0 Update 0 Options 0
    Publish 0

SDP application statistics:
 Parses: 0,  Builds 0
 Invalid token order: 0,  Invalid param: 0
 Not SDP desc: 0,  No resource: 0

Last time SIP Statistics were cleared: <never>

      Configuration Examples for TDoS Attack Mitigation

      Example: Trusted IP Address List Configuration

      The following example shows how to configure a Trusted IP Address list.

      Device> enable
Device# configure terminal
Device(config)# voice service voip
Device(conf-voi-serv)# ip address trusted list
Device(cfg-iptrust-list)# ipv4 192.0.2.1
Device(cfg-iptrust-list)# ipv6 2001:DB8:0:ABCD::1/48

      Example: TDoS Attack Mitigation Configuration

      The following example shows how to configure TDoS Attack Mitigation.

      Device> enable
Device# configure terminal
Device(config)# voice service voip
Device(conf-voi-serv)# ip address trusted authenticate
Device(conf-voi-serv)# allow-connections sip to sip
Device(conf-voi-serv)# sip
Device(conf-serv-sip)# no registrar server
Device(conf-serv-sip)# silent-discard untrusted

      Feature Information for TDoS Attack Mitigation

      The following table provides release information about the feature or features described in this module. This table lists only the software release that introduced support for a given feature in a given software release train. Unless noted otherwise, subsequent releases of that software release train also support that feature.

      Use Cisco Feature Navigator to find information about platform support and Cisco software image support. To access Cisco Feature Navigator, go to . An account on Cisco.com is not required.
      Table 1 Feature Information for TDoS Mitigation

      Feature Name

      Release

      Feature Information

      TDoS Attack Mitigation

      15.3(3)M

      The TDoS Attack Mitigation feature enables Cisco UBE to not respond to Session Initiation Protocol (SIP) requests from IP addresses that are not listed in a trusted IP address list.

      TDoS Attack Mitigation

      Cisco IOS XE Release 3.10S

      The TDoS Attack Mitigation feature enables Cisco UBE to not respond to Session Initiation Protocol (SIP) requests from IP addresses that are not listed in a trusted IP address list.