What is SIP ALG and How to disable it. - Flex UC Help

SIP ALG stands for Application Layer Gateway and is common in all many ... openwrt, No ALG feature – Consider using a public STUN server. Home Troubleshooting WhatisSIPALGandHowtodisableit. SearchFor Search Searchfor: Contents WhatisSIPALG?HowcanitaffectVoIP?IhavedisabledSIPALGbutI'mstillexperiencingproblems... SubscribeTogetKnowledgeBaseUpdates Pleaseleavethisfieldempty Checkyourinboxorspamfoldertoconfirmyoursubscription. Contents WhatisSIPALG?HowcanitaffectVoIP?IhavedisabledSIPALGbutI'mstillexperiencingproblems... WhatisSIPALG? SIPALGstandsforApplicationLayerGatewayandiscommoninallmanycommercialrouters.ItspurposeistopreventsomeoftheproblemscausedbyrouterfirewallsbyinspectingVoIPtraffic(packets)andifnecessarymodifyingit. ManyroutershaveSIPALGturnedonbydefault. There arevarioussolutionsforSIPclientsbehindNAT,someofthemintheclientside(STUN, TURN, ICE),othersareintheserverside(ProxyRTPas RtpProxy,MediaProxy). Generallyspeaking,ALGworkstypicallyintheclientside LANrouterorgateway.Insomescenarios,someclient-sidesolutionsarenotvalid,forexample,STUNwithsymmetricalNATrouter.IftheSIPproxydoesn’tprovideaserver-sideNATsolution,thenanALGsolutioncouldhaveaplace. AnALGunderstandstheprotocolusedbythespecificapplicationsthatitsupports(inthiscaseSIP)anddoesaprotocolpacket-inspectionoftrafficthroughit.ANATrouterwithabuilt-inSIPALGcanre-writeinformationwithintheSIPmessages(SIPheadersandSDPbody)makingsignallingandaudiotrafficbetweentheclientbehindNATandtheSIPendpointpossible. HowcanitaffectVoIP? EventhoughSIPALGisintendedtoassistuserswhohavephonesonprivateIPaddresses(ClassC192.168.X.X),inmanycasesitisimplementedpoorlyandactuallycausesmoreproblemsthanitsolves.SIPALGmodifiesSIPpacketsinunexpectedways,corruptingthemandmakingthemunreadable.Thiscangiveyouunexpectedbehaviour,suchasphonesnotregisteringandincomingcallsfailing. ThereforeifyouareexperiencingproblemswerecommendthatyoucheckyourroutersettingsandturnSIPALGoffifitisenabled. Lackofincomingcalls: WhenaUAisswitchedonitsendsaREGISTERrequesttotheproxyinordertobelocalisableandreceiveanyincomingcalls.ThisREGISTERismodifiedbytheALGfeature(ifnottheuserwouldn’tbereachablebytheproxysinceitindicatedaprivateIPinREGISTER“Contact”header).CommonroutersjustmaintaintheUDP“connection”openforawhile(30-60seconds)soafterthattimetheportforwardingisendedandincomingpacketsarediscardedbytherouter.ManySIPproxiesmaintaintheUDPkeepalivebysendingOPTIONSorNOTIFYmessagestotheUA,buttheyjustdoitwhentheUAhasbeendetectedasNAT’dduringtheregistration.ASIPALGrouterrewritestheREGISTERrequesttotheproxydoesn’tdetecttheNATanddoesn’tmaintainthekeepalive(soincomingcallswillbenotpossible).BreakingSIPsignalling: ManyoftheactualcommonrouterswithinbuiltSIPALGmodifySIPheadersandtheSDPbodyincorrectly,breakingSIPandmakingcommunicationjustimpossible.Someofthemdoawholereplacingbysearchingaprivateaddressin all SIPheadersandbodyandreplacingthemwiththerouterpublicmappedaddress(forexample,replacingtheprivateaddressifitappearsin“Call-ID”header,whichmakesnosenseatall).ManySIPALGrouterscorrupttheSIPmessagewhenwritingintoit(i.e.missedsemi-colon“;”inheaderparameters).Writingincorrectportvaluesgreaterthan65536isalsocommoninmanyoftheserouters.Disallowsserver-sidesolutions: Evenifyoudon’tneedaclient-sideNATsolution(yourSIPproxygivesyouaserverNATsolution),ifyourrouterhasSIPALGenabledthatbreaksSIPsignalling,itwillmakecommunicationwithyourproxyimpossible. IhavedisabledSIPALGbutI’mstillexperiencingproblems… IfyouarestillhavingproblemsafterdisablingSIPALG,pleasecheckyourfirewallconfiguration. Mosthome/residentialroutershaveawebinterface.Typicallythisis192.168.1.1butyoujustcheckyourdefaultgateway bytyping ipconfig inWindowscommandpromptor ifconfig onLinuxsystemsfrom anyconnecteddevice onthesameLAN.IfyourrouterdoesnothaveawebinterfaceyouwillmostlikelyneedaTelnetclientto login.Ifyoudon’thaveatelnetclientinstalledwerecommend Smartty(smartty.sysprogs.com)Connectin telnettotheIPv4addressofyourgatewayandhitenteragain. AsusRoutersDisabletheoptionSIPPassthroughunderAdvancedSettings/WAN->NATPassthrough.Ifyourrouterdoesn’thavethisoptionSIPALGmaybedisabledviaTelnet.nvramgetnf_sip (Itshouldreturna“1”)nvramsetnf_sip=0 nvramcommitRebootAVMFritz!BoxSIPALGcannotbedisabled. (Seeaboveonhowtogetaroundthis)BarracudaFirewallsGotoFirewall>FirewallRules>CustomFirewallAccessRulesClickthe“Disabled”checkboxnexttoanyrulesnamedLAN-2-INTERNET-SIPandINTERNET-2-LAN-SIPThisdisablesSIPALG.BillionNavigatetothewebinterface->SelectConfiguration->Select NAT->Select ALG->DisableSIPALGBT(Homehubs)SIPALGcannotbedisabledinthesettingsofBTHomeHubsbutcanbedisabledwithBTBusinessHubversions3andhigher.CiscoRVRange(RV082,RV016,RV042,RV042G,RV325)->GotoSystemSummaryandensurethatthefirmwareisuptodate(1.1.1.06orlater).->fneeded,updatefirmwarebygoingtoSystemManagement>FirmwareUpgrade.->GotoFirewall>General.->EnsurethatFirewallandRemoteManagementareenabled(checked).->Ensurethatthefollowingaredisabled(unchecked):->SPI(StatefulPacketInspection)->DoS(DenialofService)->BlockWANRequest->SIPALG->ClickSave.->BrowsetoIPADDRESS/f_general_hidden.htm.->SetUDPTimeoutto300seconds.->GotoFirewall>AccessRules.->WhitelistourIPrangesSaveallchanges.D-LinkIn‘Advanced’settings–>‘ApplicationLevelGateway(ALG)Configuration’un-tickthe‘SIP’option.DD-WRTNoALGfunctionavailable–ConsiderusingapublicSTUNserverDrayTekDrayTekVigor2760devices,theoptioncanbefoundintheregularinterfaceatNetwork->NAT->ALG.Ifyourdevicedoesnothaveawebinterfacethenyou’llneedatelnetclient.Youwillbepromptedtoprovideausernameand/orpassword.Thesearethesamecredentialsusedtoaccesstherouter’swebinterface.Afterwards,typeinthesecommands:syssip_alg0syscommitOnDraytekVigor2750andVigor2130pleaseusethesecommandsinstead:kmodule_ctlnf_nat_sipdisablekmodule_ctlnf_conntrack_sipdisableEEHuaweiE5330NavigatetothewebinterfaceClickSettings.Entertherequiredusernameandpassword,thenclickLogIn. Note:Thedefaultusernameandpasswordisadmin.ClicktheSecuritydropdown.ClickSIPALGSettings.UnticktheEnableSIPALGbox.ClickApply.FortinetFortigate:DisablingtheSIPALGinaVoIPprofileSIPisenabledbydefaultinaVoIPprofile.IfyouarejustusingtheVoIPprofileforSCCPyoucanusethefollowingcommandtodisableSIPintheVoIPprofile.configvoipprofileeditVoIP_Pro_2configsipsetstatusdisableendHuaweiTheSIPALGsettingisusuallyfoundintheSecuritymenu.Vodafone/Huawei(HHG2500)TalkTalk/Huawei(HG633) EE/ Huawei(E5330)JuniperTypethefollowingintotheCLITocheckifcurrentlyenabledordisabledrun showsecurity alg status|matchsipTodisablerun:configuresetsecurityalgsipdisablecommitLinksys:CheckforaSIPALGoptionintheAdministrationtabunder‘Advanced’.Youshouldalso disabletheSPIFirewalloption.MikrotikDisableSIPHelper.NetgearLookfora‘SIPALG’checkboxin‘WAN’settings.Under‘NATFiltering’unchecktheoption‘SIPALG’PortScanandDoSProtectionshouldalsobedisabled.DisableSTUNinVoIPphone’ssettings.openwrtNoALGfeature–ConsiderusingapublicSTUNserverSonicWALLFirewallUndertheVoIPtab,theoption‘EnableConsistentNAT’shouldbeenabledand‘EnableSIPTransformations’unchecked.Detailedinstructionscanbefoundhere: http://help.flexuc.io/knowledge-base/sonicwall-recommended-settings-for-voip/SpeedtouchTodisableSIPALGyouneedtotelnetintoyourSpeedtouchrouterandtypethefollowing:->connectionunbindapplication=SIPport=5060->saveallTalkTalk2017/18SeeHuawei (HG633)NavigatetothewebinterfaceSelect‘PortForwarding’fromthemenuUncheckSIP-ALGfromtheALGsectionatthebottomofthepage.Technicolor/ThompsonTG588TG589TG582DWA0120OpenCommandPrompt–“Start”→“Run”→type“cmd”andpress“Enter”.InCommandPrompt,type“telnet192.168.1.254”andpressenter.192.168.1.254isthedefaultIPaddressoftherouter.IfyouarerunningonWindows7/8/8.1/10,youmightneedtoinstallthetelnetclientfrom“ControlPanel”→“ProgramsandFeatures”→“TurnWindowsfeaturesonandoff”.Thedefaultusernameis“Administrator”,andthereisnodefaultpassword,leaveblank.Type“connectionunbindapplication=SIPport=5060”andpress“Enter”.Type“saveall”andpress“Enter”.Type“exit”andpress“Enter”toexitthetelnetsession.TomatoDependingontheversionofTomato,SIPALGcanbefoundunderAdvancedthenConntrack/NetfilterintheTracking/NATHelperssection.IfyoufindSIPcheckedthenSIPALGisenabled.Uncheckittodisableit.TP-LinkNavigatetoyourrouterswebinterface.Thedefaultusernameisadminandthedefaultpasswordis admin.Ontheleft,clickonAdvancedSetupandthenclickonNATandthenclickonALG.UnchecktheboxbySIPEnabled.(SomeTPfirmwareshowsthisasSIPTransformationswhichisthesamething).ClickSave/Apply.UBEEGatewaysGotoAdvanced>Options.Disable(uncheck)SIP.Disable(uncheck)RTSP.ClickApply.UbiquitiUsetheconfigurationtreeifsupported:system->conntrack->modules->sip->disableAlternatively,youcanSSHintothedeviceandrunthefollowingcommands:configuresetsystemconntrackmodulessipdisablecommitsaveexitVirginSuperHubSIPALGcannotbedisabledinthesettingsofSuperHubs.Pleaseseeourworkaroundsatthetopofthepage.Vodafone2018Onwards–SeeHuawei(HHG2500)Vyatta/Brocade:TypethefollowingintotheCLIconfiguresetsystem conntrack modulessipdisablecommitsaveexitZyXELUnderNetworkorAdvanced->ALGun-ticktheoptionsEnableSIPALGandEnableSIPTransformations.TelnetcommandsmustbeusedtodisableSIPALGwithsomeotherZyxelrouters.Telnetintotherouter.Selectmenuitems24then8.TodisplaythecurrentSIPALGstatusrunthefollowingcommand:ipnatservicesipactiveToturnoffSIPALG:ipnatservicesipactive0ZyXEL(ZyWALLUSGRouters)GotoSettings>Configuration>Network>ALG.DisableSIPALG.TurnONEnableSIPTransformations.TurnOFFEnableConfigureSIPInactivityTimeout. UpdatedonNovember17,2021 Wasthisarticlehelpful? Yes No RelatedArticles HowtoClearyourDNSCache IPPhoneRegistrationIssuesovertheBellCanadaFibreorDSLHubmodem/routercombo IPPhoneDisplays“NoService”,or“LineUnableToRegister” IPPhonewillnotpowerupusingPoE IPPhonewillnotpowerupusingExternalPowerSupply IPPhone–NetworkNotAvailable