Re: [sr-dev] Proxy protocol issue

[Daniel-Constantin Mierla]

Hello,

if it is needed/useful, then new fields can be added in the internal
structures (e.g., tcp connection, received info)  to keep the haproxy
address/port.

Otherwise, I haven't needed to haproxy so far to become familiar with,
so cannot comment much, but adding an alias seems to be the right approach.

Cheers,
Daniel

On 18.10.21 16:42, Federico Cabiddu wrote:
> Hi Arsen and Sergey,
> actually the protocol's specs say that the destination ip and port
> fields of the protocol have to be considered as "the ones the server
> would get using getsockname()", so Arsen is right and the
> implementation in kamailio is strictly correct.
> However, as I said, this implementation is preventing kamailio from
> re-using the already established tcp connection for sending messages
> to the connection initiator, e.g. in-dialog messages for a call.
> I can force the tcp connection to be used for such messages by means
> of tcp_set_otcipd
> (https://kamailio.org/docs/modules/devel/modules/tcpops.html#tcpops.f.tcp_set_otcpid
> ),
> e.g. saving the tcp connection id into a Record-Route parameter to be
> retrieved during loose routed messages handling, I think that a tcp
> alias reflecting the original destination ip/port could be added to
> the aliases' list, to make the re-usage transparent.
> I'll prepare a PR for this.
> Thanks for the feedback.
>
> Federico
>
>
>
> On Fri, Oct 15, 2021 at 2:25 PM Arsen Semenov  > wrote:
>
> Hi Sergey,
> What Frederico talks about wouldn't lead to opening a new
> connection towards LB/HAproxy, instead Kamailio should find a
> connection by alias and re-use it. 
>
> Frederico, I did not test with commenting the dst ip overwriting,
> in my tests I was trying to find a connection by using 0 for
> local_ip for calls originated from behind proxy protocol, it was
> working, but I'm not sure this is the best option here.  
>
> I am wondering if there is anyone who actually uses proxy protocol
> in DSR scenarios? 
> maybe really need to change it in order to make "sending msg back"
> working.  
>
> On Fri, Oct 15, 2021 at 4:44 PM Sergey Safarov
> mailto:s.safa...@gmail.com>> wrote:
>
> Hi Federico
> Here is also another issue here.
> I do know how to HAproxy UDP messages but let talk about
> TCP/TLS connections.
> Imagine you know which socket ned to use to establish a new
> connection.
>
> But you are not able to do it. Because HAproxy do not provide
> the ability to establish a connection from the backend server
> to the client.
> So real socket knowled do not help you. This do work with
> HAproxy servers.
>
> What you can, establish a direct connection from Kamailio to
> the client using a different socket with a different
> "advertise" keyword.
>
> You anyway need another socket.
> Any socket that you want.
>
> Maybe you need anycast Kamailio installation?
>
> Sergey
>
> On Fri, Oct 15, 2021 at 2:27 PM Federico Cabiddu
>  > wrote:
>
> Hi Arsen,
> the issue is exactly that kamailio behind HA LB DON'T
> reuse the same connection because there is no tcp alias
> for CLIENT_IP/LOCAL_KAMAILIO_IP, because the kamailio
> local socket has been overwritten by the balancer IP. I've
> read the specification and nowhere is written that the
> load balancer IP must overwrite the local socket
> information. With the actual implementation it is
> impossible to send back a message (not a reply, a brand
> new one) to the client, because there is no matching tcp
> alias (I've done a quite deep debug). Proxy protocol was
> mainly taught for unidirectional flows (http), not for
> SIP. IMHO it is useless , if not dangerous, that the local
> socket is rewritten with an IP that doesn't belong to
> kamailio. Commenting the dst ip overwriting makes kamailio
> create the correct alias for the tcp connection and reuse
> it to send, in example, a BYE message from the callee to
> the caller.
>
> Cheers,
>
> Federico
>
> On Fri, Oct 15, 2021 at 12:40 PM Arsen Semenov
> mailto:arsper...@gmail.com>> wrote:
>
> Hi Federico,
>
> I was facing the same issues when I was playing with
> the proxy protocol some time ago.
> As per my understanding the way how proxy protocol(PP)
> is implemented in Kamailio is outlined in the de-facto
> standard doc:
> https://www.haproxy.org/download/1.8/doc/pro

Re: [sr-dev] Proxy protocol issue

[Federico Cabiddu]

Hi Arsen and Sergey,
actually the protocol's specs say that the destination ip and port fields
of the protocol have to be considered as "the ones the server would get
using getsockname()", so Arsen is right and the implementation in kamailio
is strictly correct.
However, as I said, this implementation is preventing kamailio from
re-using the already established tcp connection for sending messages to the
connection initiator, e.g. in-dialog messages for a call.
I can force the tcp connection to be used for such messages by means of
tcp_set_otcipd (
https://kamailio.org/docs/modules/devel/modules/tcpops.html#tcpops.f.tcp_set_otcpid),
e.g. saving the tcp connection id into a Record-Route parameter to be
retrieved during loose routed messages handling, I think that a tcp alias
reflecting the original destination ip/port could be added to the aliases'
list, to make the re-usage transparent.
I'll prepare a PR for this.
Thanks for the feedback.

Federico



On Fri, Oct 15, 2021 at 2:25 PM Arsen Semenov  wrote:

> Hi Sergey,
> What Frederico talks about wouldn't lead to opening a new connection
> towards LB/HAproxy, instead Kamailio should find a connection by alias and
> re-use it.
>
> Frederico, I did not test with commenting the dst ip overwriting, in my
> tests I was trying to find a connection by using 0 for local_ip for calls
> originated from behind proxy protocol, it was working, but I'm not sure
> this is the best option here.
>
> I am wondering if there is anyone who actually uses proxy protocol in DSR
> scenarios?
> maybe really need to change it in order to make "sending msg back"
> working.
>
> On Fri, Oct 15, 2021 at 4:44 PM Sergey Safarov 
> wrote:
>
>> Hi Federico
>> Here is also another issue here.
>> I do know how to HAproxy UDP messages but let talk about TCP/TLS
>> connections.
>> Imagine you know which socket ned to use to establish a new connection.
>>
>> But you are not able to do it. Because HAproxy do not provide the ability
>> to establish a connection from the backend server to the client.
>> So real socket knowled do not help you. This do work with HAproxy servers.
>>
>> What you can, establish a direct connection from Kamailio to the client
>> using a different socket with a different "advertise" keyword.
>>
>> You anyway need another socket.
>> Any socket that you want.
>>
>> Maybe you need anycast Kamailio installation?
>>
>> Sergey
>>
>> On Fri, Oct 15, 2021 at 2:27 PM Federico Cabiddu <
>> federico.cabi...@gmail.com> wrote:
>>
>>> Hi Arsen,
>>> the issue is exactly that kamailio behind HA LB DON'T reuse the same
>>> connection because there is no tcp alias for CLIENT_IP/LOCAL_KAMAILIO_IP,
>>> because the kamailio local socket has been overwritten by the balancer IP.
>>> I've read the specification and nowhere is written that the load balancer
>>> IP must overwrite the local socket information. With the actual
>>> implementation it is impossible to send back a message (not a reply, a
>>> brand new one) to the client, because there is no matching tcp alias (I've
>>> done a quite deep debug). Proxy protocol was mainly taught for
>>> unidirectional flows (http), not for SIP. IMHO it is useless , if not
>>> dangerous, that the local socket is rewritten with an IP that doesn't
>>> belong to kamailio. Commenting the dst ip overwriting makes kamailio create
>>> the correct alias for the tcp connection and reuse it to send, in example,
>>> a BYE message from the callee to the caller.
>>>
>>> Cheers,
>>>
>>> Federico
>>>
>>> On Fri, Oct 15, 2021 at 12:40 PM Arsen Semenov 
>>> wrote:
>>>
 Hi Federico,

 I was facing the same issues when I was playing with the proxy protocol
 some time ago.
 As per my understanding the way how proxy protocol(PP) is implemented
 in Kamailio is outlined in the de-facto standard doc:
 https://www.haproxy.org/download/1.8/doc/proxy-protocol.txt

 "
 The PROXY protocol's goal is to fill the server's internal structures
 with the
 information collected by the proxy that the server would have been able
 to get
 by itself if the client was connecting directly to the server instead
 of via a
 proxy. The information carried by the protocol are the ones the server
 would
 get using getsockname() and getpeername() :
   - address family (AF_INET for IPv4, AF_INET6 for IPv6, AF_UNIX)
   - socket protocol (SOCK_STREAM for TCP, SOCK_DGRAM for UDP)
   - layer 3 source and destination addresses
   - layer 4 source and destination ports if any
 "

 So that internally Kamailio will have info of Client
 source_ip:source_port/LB_external_IP:LB_external_port
 You can confirm that by executing core.tcp_list command.

 For a call initiated by a client behind LB with proxy protocol,
 responses will re-use existing TCP connection and will reach the client.
 But for example if the call will be terminated from the callee side, (i.e
 new transaction) Kamailio will

Re: [sr-dev] Proxy protocol issue

[Arsen Semenov]

Hi Sergey,
What Frederico talks about wouldn't lead to opening a new connection
towards LB/HAproxy, instead Kamailio should find a connection by alias and
re-use it.

Frederico, I did not test with commenting the dst ip overwriting, in my
tests I was trying to find a connection by using 0 for local_ip for calls
originated from behind proxy protocol, it was working, but I'm not sure
this is the best option here.

I am wondering if there is anyone who actually uses proxy protocol in DSR
scenarios?
maybe really need to change it in order to make "sending msg back"
working.

On Fri, Oct 15, 2021 at 4:44 PM Sergey Safarov  wrote:

> Hi Federico
> Here is also another issue here.
> I do know how to HAproxy UDP messages but let talk about TCP/TLS
> connections.
> Imagine you know which socket ned to use to establish a new connection.
>
> But you are not able to do it. Because HAproxy do not provide the ability
> to establish a connection from the backend server to the client.
> So real socket knowled do not help you. This do work with HAproxy servers.
>
> What you can, establish a direct connection from Kamailio to the client
> using a different socket with a different "advertise" keyword.
>
> You anyway need another socket.
> Any socket that you want.
>
> Maybe you need anycast Kamailio installation?
>
> Sergey
>
> On Fri, Oct 15, 2021 at 2:27 PM Federico Cabiddu <
> federico.cabi...@gmail.com> wrote:
>
>> Hi Arsen,
>> the issue is exactly that kamailio behind HA LB DON'T reuse the same
>> connection because there is no tcp alias for CLIENT_IP/LOCAL_KAMAILIO_IP,
>> because the kamailio local socket has been overwritten by the balancer IP.
>> I've read the specification and nowhere is written that the load balancer
>> IP must overwrite the local socket information. With the actual
>> implementation it is impossible to send back a message (not a reply, a
>> brand new one) to the client, because there is no matching tcp alias (I've
>> done a quite deep debug). Proxy protocol was mainly taught for
>> unidirectional flows (http), not for SIP. IMHO it is useless , if not
>> dangerous, that the local socket is rewritten with an IP that doesn't
>> belong to kamailio. Commenting the dst ip overwriting makes kamailio create
>> the correct alias for the tcp connection and reuse it to send, in example,
>> a BYE message from the callee to the caller.
>>
>> Cheers,
>>
>> Federico
>>
>> On Fri, Oct 15, 2021 at 12:40 PM Arsen Semenov 
>> wrote:
>>
>>> Hi Federico,
>>>
>>> I was facing the same issues when I was playing with the proxy protocol
>>> some time ago.
>>> As per my understanding the way how proxy protocol(PP) is implemented in
>>> Kamailio is outlined in the de-facto standard doc:
>>> https://www.haproxy.org/download/1.8/doc/proxy-protocol.txt
>>>
>>> "
>>> The PROXY protocol's goal is to fill the server's internal structures
>>> with the
>>> information collected by the proxy that the server would have been able
>>> to get
>>> by itself if the client was connecting directly to the server instead of
>>> via a
>>> proxy. The information carried by the protocol are the ones the server
>>> would
>>> get using getsockname() and getpeername() :
>>>   - address family (AF_INET for IPv4, AF_INET6 for IPv6, AF_UNIX)
>>>   - socket protocol (SOCK_STREAM for TCP, SOCK_DGRAM for UDP)
>>>   - layer 3 source and destination addresses
>>>   - layer 4 source and destination ports if any
>>> "
>>>
>>> So that internally Kamailio will have info of Client
>>> source_ip:source_port/LB_external_IP:LB_external_port
>>> You can confirm that by executing core.tcp_list command.
>>>
>>> For a call initiated by a client behind LB with proxy protocol,
>>> responses will re-use existing TCP connection and will reach the client.
>>> But for example if the call will be terminated from the callee side, (i.e
>>> new transaction) Kamailio will fail to find existing TCP connection since
>>> it does not know nothing about it and will try to open a new one, which, in
>>> turn will fail either because of LB reject - if so_useport is disabled, or
>>> if so_reuseport=yes because of the fact that in the OS there is already
>>> opened TCP connection with the same tuple (ie. between LB and Kamailio
>>> host)
>>> So the way to use proxy protocol in Kamailio is DSR (direct server
>>> return) scenarios.
>>>
>>> here you can find related conversation:
>>> https://github.com/kamailio/kamailio/issues/2103
>>>
>>>
>>> Regards,
>>>
>>> On Fri, Oct 15, 2021 at 2:43 PM Federico Cabiddu <
>>> federico.cabi...@gmail.com> wrote:
>>>
 Hi all,
 I've been recently testing kamailio support for proxy protocol which
 was introduced by https://github.com/kamailio/kamailio/issues/1757. As
 reported by others, even if kamailio is able to decode the proxy protocol
 and get the client's original IP address, it is unable to send SIP messages
 to the client which initiated the connection through the HA load balancer
 (nginx in my case). After investigation 

Re: [sr-dev] Proxy protocol issue

[Sergey Safarov]

Hi Federico
Here is also another issue here.
I do know how to HAproxy UDP messages but let talk about TCP/TLS
connections.
Imagine you know which socket ned to use to establish a new connection.

But you are not able to do it. Because HAproxy do not provide the ability
to establish a connection from the backend server to the client.
So real socket knowled do not help you. This do work with HAproxy servers.

What you can, establish a direct connection from Kamailio to the client
using a different socket with a different "advertise" keyword.

You anyway need another socket.
Any socket that you want.

Maybe you need anycast Kamailio installation?

Sergey

On Fri, Oct 15, 2021 at 2:27 PM Federico Cabiddu 
wrote:

> Hi Arsen,
> the issue is exactly that kamailio behind HA LB DON'T reuse the same
> connection because there is no tcp alias for CLIENT_IP/LOCAL_KAMAILIO_IP,
> because the kamailio local socket has been overwritten by the balancer IP.
> I've read the specification and nowhere is written that the load balancer
> IP must overwrite the local socket information. With the actual
> implementation it is impossible to send back a message (not a reply, a
> brand new one) to the client, because there is no matching tcp alias (I've
> done a quite deep debug). Proxy protocol was mainly taught for
> unidirectional flows (http), not for SIP. IMHO it is useless , if not
> dangerous, that the local socket is rewritten with an IP that doesn't
> belong to kamailio. Commenting the dst ip overwriting makes kamailio create
> the correct alias for the tcp connection and reuse it to send, in example,
> a BYE message from the callee to the caller.
>
> Cheers,
>
> Federico
>
> On Fri, Oct 15, 2021 at 12:40 PM Arsen Semenov 
> wrote:
>
>> Hi Federico,
>>
>> I was facing the same issues when I was playing with the proxy protocol
>> some time ago.
>> As per my understanding the way how proxy protocol(PP) is implemented in
>> Kamailio is outlined in the de-facto standard doc:
>> https://www.haproxy.org/download/1.8/doc/proxy-protocol.txt
>>
>> "
>> The PROXY protocol's goal is to fill the server's internal structures
>> with the
>> information collected by the proxy that the server would have been able
>> to get
>> by itself if the client was connecting directly to the server instead of
>> via a
>> proxy. The information carried by the protocol are the ones the server
>> would
>> get using getsockname() and getpeername() :
>>   - address family (AF_INET for IPv4, AF_INET6 for IPv6, AF_UNIX)
>>   - socket protocol (SOCK_STREAM for TCP, SOCK_DGRAM for UDP)
>>   - layer 3 source and destination addresses
>>   - layer 4 source and destination ports if any
>> "
>>
>> So that internally Kamailio will have info of Client
>> source_ip:source_port/LB_external_IP:LB_external_port
>> You can confirm that by executing core.tcp_list command.
>>
>> For a call initiated by a client behind LB with proxy protocol, responses
>> will re-use existing TCP connection and will reach the client. But for
>> example if the call will be terminated from the callee side, (i.e new
>> transaction) Kamailio will fail to find existing TCP connection since it
>> does not know nothing about it and will try to open a new one, which, in
>> turn will fail either because of LB reject - if so_useport is disabled, or
>> if so_reuseport=yes because of the fact that in the OS there is already
>> opened TCP connection with the same tuple (ie. between LB and Kamailio
>> host)
>> So the way to use proxy protocol in Kamailio is DSR (direct server
>> return) scenarios.
>>
>> here you can find related conversation:
>> https://github.com/kamailio/kamailio/issues/2103
>>
>>
>> Regards,
>>
>> On Fri, Oct 15, 2021 at 2:43 PM Federico Cabiddu <
>> federico.cabi...@gmail.com> wrote:
>>
>>> Hi all,
>>> I've been recently testing kamailio support for proxy protocol which was
>>> introduced by https://github.com/kamailio/kamailio/issues/1757. As
>>> reported by others, even if kamailio is able to decode the proxy protocol
>>> and get the client's original IP address, it is unable to send SIP messages
>>> to the client which initiated the connection through the HA load balancer
>>> (nginx in my case). After investigation I've found that there is no alias
>>> added to the tcp connection aliases list for the tuple
>>> CLIENT_IP:CLIENT_PORT/LOCAL_KAMAILIO_IP:KAMAILIO_PORT. This means that when
>>> trying to forward a message to the originating client kamailio won't use
>>> the existing connection with the load balancer/proxy but will try to
>>> establish a new connection. The fact is that the function which parses the
>>> proxy header overwrites the dst ip/port of the connection with the
>>> "Destination IP" and "Destination Port" fields of the proxy header (
>>> https://github.com/kamailio/kamailio/blob/f677dea597db6ceaa66a2755dd6e9e738855dc35/src/core/tcp_main.c#L989
>>> for v2,
>>> https://github.com/kamailio/kamailio/blob/f677dea597db6ceaa66a2755dd6e9e738855dc35/src/core/tcp_main.c#L10

Re: [sr-dev] Proxy protocol issue

[Federico Cabiddu]

Hi Arsen,
the issue is exactly that kamailio behind HA LB DON'T reuse the same
connection because there is no tcp alias for CLIENT_IP/LOCAL_KAMAILIO_IP,
because the kamailio local socket has been overwritten by the balancer IP.
I've read the specification and nowhere is written that the load balancer
IP must overwrite the local socket information. With the actual
implementation it is impossible to send back a message (not a reply, a
brand new one) to the client, because there is no matching tcp alias (I've
done a quite deep debug). Proxy protocol was mainly taught for
unidirectional flows (http), not for SIP. IMHO it is useless , if not
dangerous, that the local socket is rewritten with an IP that doesn't
belong to kamailio. Commenting the dst ip overwriting makes kamailio create
the correct alias for the tcp connection and reuse it to send, in example,
a BYE message from the callee to the caller.

Cheers,

Federico

On Fri, Oct 15, 2021 at 12:40 PM Arsen Semenov  wrote:

> Hi Federico,
>
> I was facing the same issues when I was playing with the proxy protocol
> some time ago.
> As per my understanding the way how proxy protocol(PP) is implemented in
> Kamailio is outlined in the de-facto standard doc:
> https://www.haproxy.org/download/1.8/doc/proxy-protocol.txt
>
> "
> The PROXY protocol's goal is to fill the server's internal structures with
> the
> information collected by the proxy that the server would have been able to
> get
> by itself if the client was connecting directly to the server instead of
> via a
> proxy. The information carried by the protocol are the ones the server
> would
> get using getsockname() and getpeername() :
>   - address family (AF_INET for IPv4, AF_INET6 for IPv6, AF_UNIX)
>   - socket protocol (SOCK_STREAM for TCP, SOCK_DGRAM for UDP)
>   - layer 3 source and destination addresses
>   - layer 4 source and destination ports if any
> "
>
> So that internally Kamailio will have info of Client
> source_ip:source_port/LB_external_IP:LB_external_port
> You can confirm that by executing core.tcp_list command.
>
> For a call initiated by a client behind LB with proxy protocol, responses
> will re-use existing TCP connection and will reach the client. But for
> example if the call will be terminated from the callee side, (i.e new
> transaction) Kamailio will fail to find existing TCP connection since it
> does not know nothing about it and will try to open a new one, which, in
> turn will fail either because of LB reject - if so_useport is disabled, or
> if so_reuseport=yes because of the fact that in the OS there is already
> opened TCP connection with the same tuple (ie. between LB and Kamailio
> host)
> So the way to use proxy protocol in Kamailio is DSR (direct server return)
> scenarios.
>
> here you can find related conversation:
> https://github.com/kamailio/kamailio/issues/2103
>
>
> Regards,
>
> On Fri, Oct 15, 2021 at 2:43 PM Federico Cabiddu <
> federico.cabi...@gmail.com> wrote:
>
>> Hi all,
>> I've been recently testing kamailio support for proxy protocol which was
>> introduced by https://github.com/kamailio/kamailio/issues/1757. As
>> reported by others, even if kamailio is able to decode the proxy protocol
>> and get the client's original IP address, it is unable to send SIP messages
>> to the client which initiated the connection through the HA load balancer
>> (nginx in my case). After investigation I've found that there is no alias
>> added to the tcp connection aliases list for the tuple
>> CLIENT_IP:CLIENT_PORT/LOCAL_KAMAILIO_IP:KAMAILIO_PORT. This means that when
>> trying to forward a message to the originating client kamailio won't use
>> the existing connection with the load balancer/proxy but will try to
>> establish a new connection. The fact is that the function which parses the
>> proxy header overwrites the dst ip/port of the connection with the
>> "Destination IP" and "Destination Port" fields of the proxy header (
>> https://github.com/kamailio/kamailio/blob/f677dea597db6ceaa66a2755dd6e9e738855dc35/src/core/tcp_main.c#L989
>> for v2,
>> https://github.com/kamailio/kamailio/blob/f677dea597db6ceaa66a2755dd6e9e738855dc35/src/core/tcp_main.c#L1071
>> for v1). This fields contain the IP/port of the Load Balancer, not the
>> kamailio IP/Port, and kamailio will fail to find a tcp connection toward
>> the client's src IP since the Load Balancer IP is not a kamailio's local
>> socket.
>> I think that the destination IP of the connection shouldn't be rewritten
>> with the load balancer IP, unless I'm missing something.
>> Hopefully I've been clear enough explaining the issue :)
>> If you agree with the analysis I can prepare a PR for it.
>>
>> Have you all a great weekend,
>>
>> Federico Cabiddu
>>
>> ___
>> Kamailio (SER) - Development Mailing List
>> sr-dev@lists.kamailio.org
>> https://lists.kamailio.org/cgi-bin/mailman/listinfo/sr-dev
>>
>
>
> --
> Arsen Semenov
>
> ___

Re: [sr-dev] Proxy protocol issue

[Arsen Semenov]

Hi Federico,

I was facing the same issues when I was playing with the proxy protocol
some time ago.
As per my understanding the way how proxy protocol(PP) is implemented in
Kamailio is outlined in the de-facto standard doc:
https://www.haproxy.org/download/1.8/doc/proxy-protocol.txt

"
The PROXY protocol's goal is to fill the server's internal structures with
the
information collected by the proxy that the server would have been able to
get
by itself if the client was connecting directly to the server instead of
via a
proxy. The information carried by the protocol are the ones the server would
get using getsockname() and getpeername() :
  - address family (AF_INET for IPv4, AF_INET6 for IPv6, AF_UNIX)
  - socket protocol (SOCK_STREAM for TCP, SOCK_DGRAM for UDP)
  - layer 3 source and destination addresses
  - layer 4 source and destination ports if any
"

So that internally Kamailio will have info of Client
source_ip:source_port/LB_external_IP:LB_external_port
You can confirm that by executing core.tcp_list command.

For a call initiated by a client behind LB with proxy protocol, responses
will re-use existing TCP connection and will reach the client. But for
example if the call will be terminated from the callee side, (i.e new
transaction) Kamailio will fail to find existing TCP connection since it
does not know nothing about it and will try to open a new one, which, in
turn will fail either because of LB reject - if so_useport is disabled, or
if so_reuseport=yes because of the fact that in the OS there is already
opened TCP connection with the same tuple (ie. between LB and Kamailio
host)
So the way to use proxy protocol in Kamailio is DSR (direct server return)
scenarios.

here you can find related conversation:
https://github.com/kamailio/kamailio/issues/2103


Regards,

On Fri, Oct 15, 2021 at 2:43 PM Federico Cabiddu 
wrote:

> Hi all,
> I've been recently testing kamailio support for proxy protocol which was
> introduced by https://github.com/kamailio/kamailio/issues/1757. As
> reported by others, even if kamailio is able to decode the proxy protocol
> and get the client's original IP address, it is unable to send SIP messages
> to the client which initiated the connection through the HA load balancer
> (nginx in my case). After investigation I've found that there is no alias
> added to the tcp connection aliases list for the tuple
> CLIENT_IP:CLIENT_PORT/LOCAL_KAMAILIO_IP:KAMAILIO_PORT. This means that when
> trying to forward a message to the originating client kamailio won't use
> the existing connection with the load balancer/proxy but will try to
> establish a new connection. The fact is that the function which parses the
> proxy header overwrites the dst ip/port of the connection with the
> "Destination IP" and "Destination Port" fields of the proxy header (
> https://github.com/kamailio/kamailio/blob/f677dea597db6ceaa66a2755dd6e9e738855dc35/src/core/tcp_main.c#L989
> for v2,
> https://github.com/kamailio/kamailio/blob/f677dea597db6ceaa66a2755dd6e9e738855dc35/src/core/tcp_main.c#L1071
> for v1). This fields contain the IP/port of the Load Balancer, not the
> kamailio IP/Port, and kamailio will fail to find a tcp connection toward
> the client's src IP since the Load Balancer IP is not a kamailio's local
> socket.
> I think that the destination IP of the connection shouldn't be rewritten
> with the load balancer IP, unless I'm missing something.
> Hopefully I've been clear enough explaining the issue :)
> If you agree with the analysis I can prepare a PR for it.
>
> Have you all a great weekend,
>
> Federico Cabiddu
>
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>


-- 
Arsen Semenov
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[sr-dev] Proxy protocol issue

[Federico Cabiddu]

Hi all,
I've been recently testing kamailio support for proxy protocol which was
introduced by https://github.com/kamailio/kamailio/issues/1757. As reported
by others, even if kamailio is able to decode the proxy protocol and get
the client's original IP address, it is unable to send SIP messages to the
client which initiated the connection through the HA load balancer (nginx
in my case). After investigation I've found that there is no alias added to
the tcp connection aliases list for the tuple
CLIENT_IP:CLIENT_PORT/LOCAL_KAMAILIO_IP:KAMAILIO_PORT. This means that when
trying to forward a message to the originating client kamailio won't use
the existing connection with the load balancer/proxy but will try to
establish a new connection. The fact is that the function which parses the
proxy header overwrites the dst ip/port of the connection with the
"Destination IP" and "Destination Port" fields of the proxy header (
https://github.com/kamailio/kamailio/blob/f677dea597db6ceaa66a2755dd6e9e738855dc35/src/core/tcp_main.c#L989
for v2,
https://github.com/kamailio/kamailio/blob/f677dea597db6ceaa66a2755dd6e9e738855dc35/src/core/tcp_main.c#L1071
for v1). This fields contain the IP/port of the Load Balancer, not the
kamailio IP/Port, and kamailio will fail to find a tcp connection toward
the client's src IP since the Load Balancer IP is not a kamailio's local
socket.
I think that the destination IP of the connection shouldn't be rewritten
with the load balancer IP, unless I'm missing something.
Hopefully I've been clear enough explaining the issue :)
If you agree with the analysis I can prepare a PR for it.

Have you all a great weekend,

Federico Cabiddu
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