[OpenSIPS-Users] Nathelper keepalive issue with received column in usrloc

Liviu Chircu liviu at opensips.org
Wed Dec 12 10:58:11 EST 2018


Hi Julian,

Good catch on the Contact URI params - will have to remember to 
incorporate them into the fix when the time comes for it.

You can rid OpenSIPS of all those regex substitution operations with 
this neat "$ru exploiting" trick:

     $var(ct) = "sip:1.2.3.4;lr;received=sip:10.0.0.10:40885";
     $var(ru_bak) = $ru;
     $ru = $(var(ct){param.value,received});
     $var(rcv_host) = $rd;
     $var(rcv_port) = $rp;
     $ru = $var(ru_bak);

Best regards,

Liviu Chircu
OpenSIPS Developer
http://www.opensips-solutions.com

On 12.12.2018 17:45, Julian Santer wrote:
> Hi Liviu,
>
> thank you for your help.
> Without the received header, I got some problems. The calls are being 
> send from the core to the UAC and not to the edge server.
>
> So now I implemented your workaround on my lab servers:
>
> core:
>     $var(rcv) = null;
>     $var(rcv_host) = null;
>     $var(rcv_port) = null;
>     $var(ct_uri_params) = null;
>
>     xlog("L_INFO", "PATH $(hdr(Path)) - LF_BASE");
>     if ($(hdr(Path){param.exist,received}))
>     {
>         $var(rcv) = $(hdr(Path){param.value,received});
>         $var(rcv_host) = $(var(rcv){re.subst,/sip://});
>         $var(rcv_host) = $(var(rcv_host){re.subst,/:.*//});
>         $var(rcv_port) = $(var(rcv){re.subst,/sip:.+://});
>         $var(rcv_port) = $(var(rcv_port){re.subst,/>//});
>
>         AVP_RECEIVED = "sip:" + $(ct.fields(uri){uri.user}) + "@" + 
> $var(rcv_host) + ":" + $var(rcv_port);
>         $var(ct_uri_params) = $(ct.fields(uri){uri.params});
>         if ($var(ct_uri_params) != null) {
>             AVP_RECEIVED = AVP_RECEIVED + ";" + $var(ct_uri_params);
>         }
>         xlog("L_INFO", "PATH received $var(rcv), host $var(rcv_host), 
> port $var(rcv_port), AVP_RECEIVED - LF_BASE");
>     }
>
>     if (src_ip == REGISTRAR_FAILOVER_IP)
>     {
>         if (! save("LOCATION_TABLE", "mp1"))
>         {
>             xlog("L_ERR", "Saving contact from REGISTRAR_FAILOVER_IP 
> (REGISTRAR_FAILOVER) failed - LF_BASE");
>             exit;
>         }
>         xlog("L_INFO", "Saving contact received from 
> REGISTRAR_FAILOVER_IP (REGISTRAR_FAILOVER) - LF_BASE");
>         t_on_branch("BR_DROP");
>     }
>     else
>     {
>         if (proto == UDP)
>         {
>             setbflag(SIP_PING_FLAG);
>             xlog("L_INFO", "Nat keepalive sip_ping_flag - LF_BASE");
>         }
>
>         if (! save("LOCATION_TABLE", "p1"))
>         {
>             xlog("L_ERR", "Saving contact from EDGE failed - LF_BASE");
>             t_replicate("sip:REGISTRAR_FAILOVER", "0x04");
>             exit;
>         }
>         xlog("L_INFO", "Saving contact received from EDGE, replicate 
> to REGISTRAR_FAILOVER - LF_BASE");
>         t_replicate("sip:REGISTRAR_FAILOVER", "0x04");
>         t_on_branch("BR_DROP");
>     }
>
> As you can see, I also needed to add the contact uri params to the 
> received AVP. Without this params I get a 404 from the UAC.
>
> To be sure, if this workaround works, I have to publish it on the 
> production server. I will do this tomorrow morning and I hope it works 
> also with the other, undefined UAC's.
>
> Kind regards,
> Julian Santer
>
>
> Am 08.12.18 um 17:29 schrieb Liviu Chircu:
>> Hi Julian,
>>
>> This asymmetry of the OPTIONS R-URI + To header field when pinging 
>> either normal contacts (includes "username@" part) or NAT'ed  
>> contacts (skips the "username@" part) actually looks like a bug -- I 
>> will look into a fix in the background.
>>
>> For the time being, you should be able to circumvent the bug using 
>> the following technique:
>>
>> _edge script_
>>
>> no need to change anything here, using add_path_received() is correct.
>>
>> _core script_
>>
>> * define the "received_avp" modparam for both registrar and nathelper 
>> -- they must be set to the same AVP, say "$avp(rcv)"
>> * using the script transformations [1] and/or other magic, extract 
>> the value of the ";received=" Path header parameter into two 
>> convenient variables: $var(rcv_host) and $var(rcv_port).
>> * prepare the exact content of the future R-URI / To header pings for 
>> this contact by populating $avp(rcv):
>>
>>      $avp(rcv) = "sip:" + $(ct.fields(uri){uri.user}) + "@" + 
>> $var(rcv_host) + ":" + $var(rcv_port);
>>
>> * save("p1"); # notice we skip the "v" (Path ";received=" param) 
>> logic, as the received URI is already set
>>
>> Best regards,
>>
>> [1]: https://www.opensips.org/Documentation/Script-Tran-2-2
>>
>> Liviu Chircu
>> OpenSIPS Developer
>> http://www.opensips-solutions.com
>>
>> On 20.11.2018 17:01, Julian Santer wrote:
>>> Hi guys,
>>>
>>> as I see in the tcpdump:
>>>
>>> - with the received header the R-RURI in the INVITE looks like:
>>>
>>> Request-Line: INVITE sip:dev-lab1 at 192.168.44.101:40885;line=fjafxbr9 
>>> SIP/2.0
>>>
>>>
>>> - without the received header the R-URI in the INVITE looks like:
>>>
>>> Request-Line: INVITE sip:dev-lab1 at 212.46.162.97:40885;line=7wsv12yg 
>>> SIP/2.0
>>>
>>>
>>> Could the INVITE been rejeced/dropped by the UAC, if the R-RURI 
>>> contains the public instead the private IP or another port etc.?
>>>
>>> From UAC perspective, the R-RURI (puclic IP) by incoming packets 
>>> doesn't match the R-RURI (private IP) by outgoing packets.
>>>
>>>
>>> Kind regards,
>>>
>>> Julian Santer
>>>
>>> Am 20.11.18 um 15:51 schrieb Julian Santer:
>>>> Hi guys,
>>>>
>>>> if I don't use the received column on the edge server, but I call 
>>>> fix_nated_contact instead, it seems to work.
>>>>
>>>> if (nat_uac_test("127"))
>>>> {
>>>>     fix_nated_contact();
>>>> }
>>>>
>>>> consume_credentials();
>>>>
>>>> if (! add_path())
>>>> {
>>>>     send_reply("500", "Internal path error, registration not stored");
>>>>     xlog("L_ERR", "Adding PATH (with received) failed - LF_BASE");
>>>>     exit;
>>>> }
>>>>
>>>> Is this the right way or could I break something else with this 
>>>> change?
>>>>
>>>>
>>>> Kind regards,
>>>>
>>>> Julian Santer
>>>>
>>>> Am 19.11.18 um 18:41 schrieb Julian Santer:
>>>>> Hi guys,
>>>>>
>>>>> we need to switch from nat_traversal to nathelper.
>>>>> The reason is the keepalive mechanism.
>>>>>
>>>>> The nat_traversal module sends OPTIONS with the following to 
>>>>> header: sip:UAC_IP:UAC_PORT
>>>>> Most of the UAC's answers with a 404 Not found.
>>>>> On AVM Fritzbox with firmware >= 6.04, this OPTIONS may activate a 
>>>>> security feature.
>>>>> So after a certain time, the Fritzbox blocks all packages send 
>>>>> from our proxy.
>>>>> As we have ca. 80% AVM Fritzbox as UAC, we got a big problem.
>>>>> So we deactivated the nat_keepalive vor this UAC's and we have to 
>>>>> enable the keepalive Feature on the Fritzbox.
>>>>>
>>>>> The better solution would be, if we could send OPTIONS with a to 
>>>>> header like: sip:username at UAC_IP:UAC_PORT.
>>>>> As I understood the nathelper module could send OPTIONS like this. 
>>>>> Because it is looking into the userloc table. Right?
>>>>>
>>>>> The nathelper module is on our edge server, the registrar on our 
>>>>> core server.
>>>>> For the "normal" UAC's (no received entry in usrloc) the 
>>>>> keepalive's are now sent as expected.
>>>>> But for the "nated" UAC's (received entry in usrloc) the 
>>>>> keepalive's are like before: sip:UAC_IP:UAC_PORT (values in the 
>>>>> received column from usrloc).
>>>>> The REGISTER send to the core got the path header looking like:
>>>>> Path: <sip:IP_EDGE;lr;received=sip:IP_UAC:40885>
>>>>>
>>>>> Is there a possibility to add the $fU on the received part of the 
>>>>> path header (the user in the path module adds a string to the path 
>>>>> part, but not to the received part)?
>>>>> Or is there a possiblity on the registrar to store the $fU in the 
>>>>> received column?
>>>>> On the nathelper keepalive mechanism I don't see any possibility 
>>>>> to add the $fU.
>>>>>
>>>>> We are using the version 2.2.6 from the official debian source list.
>>>>>
>>>>> The config on the edge server's looks like:
>>>>> #### nat helper module
>>>>> loadmodule "nathelper.so"
>>>>> modparam("nathelper", "natping_interval", 0)
>>>>> modparam("nathelper", "ping_nated_only", 0)
>>>>> modparam("nathelper", "natping_partitions", 1)
>>>>> modparam("nathelper", "natping_tcp", 0)
>>>>>
>>>>> ### REGISTER
>>>>>
>>>>> $var(nat) = null;
>>>>>
>>>>> if (nat_uac_test("127"))
>>>>> {
>>>>>     $var(nat) = TRUE;
>>>>> }
>>>>> else
>>>>> {
>>>>>     $var(nat) = FALSE;
>>>>> }
>>>>>
>>>>> consume_credentials();
>>>>>
>>>>> if ($var(nat) == TRUE)
>>>>> {
>>>>>     if (! add_path_received())
>>>>>     {
>>>>>         xlog("L_ERR", "Adding PATH (with received) failed - 
>>>>> LF_BASE");
>>>>>         send_reply("500", "Internal path error, registration not 
>>>>> stored");
>>>>>         exit;
>>>>>     }
>>>>> }
>>>>> else
>>>>> {
>>>>>     if (! add_path())
>>>>>     {
>>>>>         send_reply("500", "Internal path error, registration not 
>>>>> stored");
>>>>>         xlog("L_ERR", "Adding PATH (with received) failed - 
>>>>> LF_BASE");
>>>>>         exit;
>>>>>     }
>>>>> }
>>>>>
>>>>> route("R_RELAY_TO_REGISTRAR");
>>>>> exit;
>>>>>
>>>>> ### OPTIONS
>>>>>
>>>>> if (method=="OPTIONS")
>>>>> {
>>>>>     if ($si == "CORE")
>>>>>     {
>>>>>         topology_hiding("U");
>>>>>         if (! t_relay("0x05"))
>>>>>         {
>>>>>             send_reply("500", "Internal server error - failed to 
>>>>> relay");
>>>>>             xlog("L_ERR", "Unable to relay OPTIONS - LF_BASE");
>>>>>         }
>>>>>     }
>>>>> }
>>>>>
>>>>>
>>>>> The config on the core server looks like:
>>>>> loadmodule "usrloc.so"
>>>>> modparam("usrloc", "user_column",           "username")
>>>>> modparam("usrloc", "domain_column",         "domain")
>>>>> modparam("usrloc", "contact_column",        "contact")
>>>>> modparam("usrloc", "expires_column",        "expires")
>>>>> modparam("usrloc", "q_column",              "q")
>>>>> modparam("usrloc", "callid_column",         "callid")
>>>>> modparam("usrloc", "cseq_column",           "cseq")
>>>>> modparam("usrloc", "methods_column",        "methods")
>>>>> modparam("usrloc", "flags_column",          "flags")
>>>>> modparam("usrloc", "user_agent_column",     "user_agent")
>>>>> modparam("usrloc", "received_column",       "received")
>>>>> modparam("usrloc", "path_column",           "path")
>>>>> modparam("usrloc", "socket_column",         "socket")
>>>>> modparam("usrloc", "use_domain",            0)
>>>>> modparam("usrloc", "desc_time_order",       0)
>>>>> modparam("usrloc", "timer_interval",        60)
>>>>> modparam("usrloc", "db_url",                "DBURL")
>>>>> modparam("usrloc", "db_mode",               2)
>>>>> modparam("usrloc", "matching_mode",         0)
>>>>> modparam("usrloc", "cseq_delay",            20)
>>>>> modparam("usrloc", "nat_bflag",             6)
>>>>>
>>>>> #### nat helper module
>>>>> loadmodule "nathelper.so"
>>>>> modparam("nathelper", "natping_interval", 56)
>>>>> modparam("nathelper", "ping_nated_only", 0)
>>>>> modparam("nathelper", "natping_partitions", 1)
>>>>> modparam("nathelper", "sipping_bflag", 8)
>>>>> modparam("nathelper", "sipping_from", "sip:keepalive at DEFAULT_REALM")
>>>>> modparam("nathelper", "sipping_method", "OPTIONS")
>>>>>
>>>>> # We want to send a keepalive on each registered UAC
>>>>> if (proto == UDP)
>>>>> {
>>>>>     setbflag(8);
>>>>>     xlog("L_INFO", "Nat keepalive sip_ping_flag - LF_BASE");
>>>>> }
>>>>>
>>>>> if (! save("location", "vp1"))
>>>>> {
>>>>>     xlog("L_ERR", "Saving contact from EDGE failed - LF_BASE");
>>>>>     exit;
>>>>> }
>>>>>
>>>>> Thank you for any hint.
>>>>>
>>>>> Kind regards,
>>>>> Julian Santer
>>>>> Raiffeisen OnLine
>>>>>
>>>>> ps: @Bogdan: this is why we have ca. 550 entry's in the address 
>>>>> table (permission module). If we solve the keepalives, only ca. 50 
>>>>> entry's are remaining.
>>>
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>>
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>
>
>
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