[OpenSIPS-Users] Intermittent TLS Problem -

Mon Jun 18 11:05:34 EDT 2018

Hi All,

Further to this issue I have established that the fault occurs when the
server does not provide a finish "Encrypted Handshake Message" following
key/cert exchange.

Based on my test patterns it seems to indicate that this improves *slightly*
over time meaning that its gets a bit more reliable after a few calls have
been processed by the remote. This doesn't mean that the calls don't ever
fail though, it goes from 50% failure rate to 20% perhaps.

Does anyone have confidence that this indicates a fault with the remote
system rather than the OpenSIPs implementation?

Thanks

On Mon, Jun 18, 2018 at 1:15 PM Callum Guy <callum.guy at x-on.co.uk> wrote:

> Hi All,
>
> I'm running a TLS protected service using OpenSIPs 2.3.3
> and openssl-1.0.2k-12.el7.x86_64 on a CentOS 7.5 server. RTPProxy is in
> place to forward all the media on every call.
>
> OpenSIPs is acting as a proxy to an internal FreeSWITCH instance and
> handling all inbound and outbound TLS negotiation.
>
> The call scenario is:
> Leg A: carrier -> opensips -> freeswitch (answer)
> Leg B: freeswitch -> opensips ->carrier
>
> I have a situation where calls sometimes fail during TLS negotiation on
> the B leg. The exact same call will work only seconds before and then the
> subsequent call will fail. This is still a test service so there is no
> traffic on the platform which would effect the calls.
>
> The destination carrier is Twilio where we are targeting a custom domain
> which provides three separate fallback IP's. The logs (below) show each
> being attempted in sequence and OpenSIPs is reporting failure.
>
> I have a packet capture (SIP encrypted) which shows that the carrier
> (Twilio) are setting up the connection and attempting to change the cipher
> spec, from my understanding it looks like this is what triggers the errors
> in OpenSIPs which then returns a SIP packet to Twilio before trying the
> next IP in the list (see screen shot below).
>
> When viewing the packet capture on a call which was not affected I don't
> see wireshark reporting "Change Cipher Spec" from the carrier network so at
> present this is the main suspicion. Unfortunately this is as far as my
> current understanding can take me so while i continue to research i wanted
> to reach out to see is anyone in the community can help! Let me know if I
> can provide any further information.
>
> Thanks!
>
> *OpenSIPs Log*
>
> Jun 18 11:20:33 opensips[6373]: INFO: [INVITE] (outbound) REST response:
> RU: sip:+35361234567 <+353%2061%20234%20567>
> @custom.pstn.ie1.twilio.com:5061;transport=tls DU: sip:
> custom.pstn.ie1.twilio.com:5061 FU: "+4940261234567 <+49%2040%20261234567>"
> <si
> ps:+4940261234567 at 172.20.0.101> To(sip:35361234567 at 172.18.0.110:5061;transport=tls)
> From(sip:+40261234567 at 172.20.0.101)
> ID:137a5be9-ed84-1236-10aa-d0431e9b59cf
> Jun 18 11:20:33 opensips[6373]: INFO:core:probe_max_sock_buff: using snd
> buffer of 416 kb
> Jun 18 11:20:33 opensips[6373]: INFO:core:init_sock_keepalive: TCP
> keepalive enabled on socket 29
> Jun 18 11:20:33 opensips[6373]: NOTICE:tls_mgm:verify_callback: depth = 2
> Jun 18 11:20:33 opensips[6373]: NOTICE:tls_mgm:verify_callback: preverify
> is good: verify return: 1
> Jun 18 11:20:33 opensips[6373]: NOTICE:tls_mgm:verify_callback: depth = 1
> Jun 18 11:20:33 opensips[6373]: NOTICE:tls_mgm:verify_callback: preverify
> is good: verify return: 1
> Jun 18 11:20:33 opensips[6373]: NOTICE:tls_mgm:verify_callback: depth = 0
> Jun 18 11:20:33 opensips[6373]: NOTICE:tls_mgm:verify_callback: preverify
> is good: verify return: 1
> *Jun 18 11:20:34 opensips[6373]: ERROR:proto_tls:tls_blocking_write: TLS
> send timeout (60)*
> *Jun 18 11:20:34 opensips[6373]: ERROR:proto_tls:proto_tls_send: failed to
> send*
> *Jun 18 11:20:34 opensips[6373]: ERROR:tm:msg_send: send()
> to 54.171.127.194:5061 <http://54.171.127.194:5061/> for proto tls/3 failed*
> *Jun 18 11:20:34 opensips[6373]: ERROR:tm:t_forward_nonack: sending
> request failed*
> Jun 18 11:20:34 opensips[6373]: INFO:core:probe_max_sock_buff: using snd
> buffer of 416 kb
> Jun 18 11:20:34 opensips[6373]: INFO:core:init_sock_keepalive: TCP
> keepalive enabled on socket 29
> Jun 18 11:20:34 opensips[6373]: NOTICE:tls_mgm:verify_callback: depth = 2
> Jun 18 11:20:34 opensips[6373]: NOTICE:tls_mgm:verify_callback: preverify
> is good: verify return: 1
> Jun 18 11:20:34 opensips[6373]: NOTICE:tls_mgm:verify_callback: depth = 1
> Jun 18 11:20:34 opensips[6373]: NOTICE:tls_mgm:verify_callback: preverify
> is good: verify return: 1
> Jun 18 11:20:34 opensips[6373]: NOTICE:tls_mgm:verify_callback: depth = 0
> Jun 18 11:20:34 opensips[6373]: NOTICE:tls_mgm:verify_callback: preverify
> is good: verify return: 1
> *Jun 18 11:20:34 opensips[6373]: ERROR:proto_tls:tls_blocking_write: TLS
> send timeout (60)*
> *Jun 18 11:20:34 opensips[6373]: ERROR:proto_tls:proto_tls_send: failed to
> send*
> *Jun 18 11:20:34 opensips[6373]: ERROR:tm:msg_send: send()
> to 54.171.127.193:5061 <http://54.171.127.193:5061/> for proto tls/3 failed*
> *Jun 18 11:20:34 opensips[6373]: ERROR:tm:t_forward_nonack: sending
> request failed*
> Jun 18 11:20:34 opensips[6373]: INFO:core:probe_max_sock_buff: using snd
> buffer of 416 kb
> Jun 18 11:20:34 opensips[6373]: INFO:core:init_sock_keepalive: TCP
> keepalive enabled on socket 29
> Jun 18 11:20:34 opensips[6373]: NOTICE:tls_mgm:verify_callback: depth = 2
> Jun 18 11:20:34 opensips[6373]: NOTICE:tls_mgm:verify_callback: preverify
> is good: verify return: 1
> Jun 18 11:20:34 opensips[6373]: NOTICE:tls_mgm:verify_callback: depth = 1
> Jun 18 11:20:34 opensips[6373]: NOTICE:tls_mgm:verify_callback: preverify
> is good: verify return: 1
> Jun 18 11:20:34 opensips[6373]: NOTICE:tls_mgm:verify_callback: depth = 0
> Jun 18 11:20:34 opensips[6373]: NOTICE:tls_mgm:verify_callback: preverify
> is good: verify return: 1
> *Jun 18 11:20:34 opensips[6373]: ERROR:proto_tls:tls_blocking_write: TLS
> send timeout (60)*
> *Jun 18 11:20:34 opensips[6373]: ERROR:proto_tls:proto_tls_send: failed to
> send*
> *Jun 18 11:20:34 opensips[6373]: ERROR:tm:msg_send: send()
> to 54.171.127.192:5061 <http://54.171.127.192:5061/> for proto tls/3 failed*
> *Jun 18 11:20:34 opensips[6373]: ERROR:tm:t_forward_nonack: sending
> request failed*
> *Jun 18 11:20:34 opensips[6373]: ERROR:tm:w_t_relay: t_forward_nonack
> failed*
> *Jun 18 11:20:34 opensips[6373]: ERROR: Failed to relay call - DU:<null>
> [INVITE] To(sip:35361234567 at 172.18.0.110:5061;transport=tls)
> From(sip:+40261234567 at 172.20.0.101 <sip%3A%2B40261234567 at 172.20.0.101>)
> ID:137a5be9-ed84-1236-10aa-d0431e9b59*
>
> *Wireshark Failure:*
> https://ibb.co/ici8Ny
>
> *Wireshark Working:*
> https://ibb.co/kePF2y
>
> --
> Callum Guy
> Head of Information Security
> X-on
>
-- 
Callum Guy
Head of Information Security
X-on

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