[asterisk-bugs] [JIRA] (ASTERISK-27879) pjsip / SRV uses wrong IP address for OPTIONS packages / qualify

[Asterisk Team (JIRA)]

     [ https://issues.asterisk.org/jira/browse/ASTERISK-27879?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Asterisk Team updated ASTERISK-27879:
-------------------------------------

    Assignee: Asterisk Team  (was: Michael Maier)
      Status: Triage  (was: Waiting for Feedback)

> pjsip / SRV uses wrong IP address for OPTIONS packages / qualify
> ----------------------------------------------------------------
>
>                 Key: ASTERISK-27879
>                 URL: https://issues.asterisk.org/jira/browse/ASTERISK-27879
>             Project: Asterisk
>          Issue Type: Bug
>      Security Level: None
>          Components: Resources/res_pjsip
>    Affects Versions: 13.21.0
>         Environment: Centos 6 / 64bit
>            Reporter: Michael Maier
>            Assignee: Asterisk Team
>              Labels: pjsip
>
> (not sure about the relevant component)
> Given is a trunk which uses SRV lookups (tel.t-online.de) and resolves to 3 hostnames / IP addresses:
> # dig _sip._udp.tel.t-online.de SRV
> ;; ANSWER SECTION:
> _sip._udp.tel.t-online.de. 2497 IN      SRV     20 0 5060 d-epp-100.edns.t-ipnet.de.
> _sip._udp.tel.t-online.de. 2497 IN      SRV     30 0 5060 h2-epp-100.edns.t-ipnet.de.
> _sip._udp.tel.t-online.de. 2497 IN      SRV     10 0 5060 n-epp-110.edns.t-ipnet.de.
> (you most probably can't exactly reproduce this lookup, because you're getting other resolutions if you're resolving from outside the telekom net).
> The problem is:
> The register is done to 
> d-epp-100.edns.t-ipnet.de (-> d...)
> - but all OPTIONS - packages are sent to 
> n-epp-110.edns.t-ipnet.de (-> n...)
> The register is done to d.. and not to n..., because n... is not reachable for my device at the moment - that's why the register uses d... and not n.
> As I'm having 3 trunks to tel.t-online.de and all of them are showing this behavior, it's seems to be that the options packages are always sent to the primary SRV DNS entry and only if it's not reachable, it is sent to the next one and so on (I can see this behavior here).
> If n... would be reachable, the packages would go out and would be denied by the provider (I could see this behavior during a short test) because n... doesn't know anything about the registration to d... .
> Could you please take care to always use the same IP address / DNS entry for each communication started for a trunk - even if there are more than one possible IP addresses? Please always use the same IP as it is used for the register.
> How to reproduce:
> - Create a trunk using SRV lookups
> - Provide more than one different entries in the SRV lookup, maybe 3 or more.
> - Block the IP of the first entry (here: _sip._udp.tel.t-online.de. 2497 IN      SRV     10 0 5060 n-epp-110.edns.t-ipnet.de.) to be not reachable by asterisk to force it to try the register using the next DNS entry.
> - Enable qualify
> => you can see the wrong OPTIONS packages in iptables log (you should log outgoing blocked packages)



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