asterisk users - Mar 2017 - tcpbind and source IP address

On Mon, Mar 13, 2017, at 08:31 AM, Kseniya Blashchuk
wrote:
> Yes, look:
> netstat -nlp | egrep '506[01]'
> tcp        0      0 192.168.0.177:5061      0.0.0.0:*              
> LISTEN
>      13255/asterisk
> udp        0      0 192.168.0.177:5060      0.0.0.0:*
>     13255/asterisk
> Still, the problem is with *outgoing* *TCP* packets originated from
> asterisk. Source IP is set to the first IP address of the interface only
> when TCP is used. As I understand, the application (chan_sip in this
> case)
> should request kernel to use the specific source IP address (used in bind
> directive) for outgoing packets, however it seems to be done only for
> UDP.
> For outgoing packets on TCP/5061 I see the following:
> IP *192.168.0.172*.47596 > <mydestip>.5061: Flags [S], seq
2529313754,
> win
> 29200, options [mss 1460,sackOK,TS val 82765588 ecr 0,nop,wscale 7],
> length
> 0
> And with UDP as transport:
> IP *192.168.0.177*.5060 > <mydestip>.5060: SIP: OPTIONS ....
The underlying code does this already. It connects using the bound
socket (which would be bound to the IP address you've provided). This
should have the system use the source IP address as you want, but it's
evidently not.

-- 
Joshua Colp
Digium, Inc. | Senior Software Developer
445 Jan Davis Drive NW - Huntsville, AL 35806 - US
Check us out at: www.digium.com & www.asterisk.org

Mmh sorry I'm afraid I did not understand your last message. Yes the code
does that but only with UDP, for TCP the source address is 192.168.0.172
though it's bound to 192.168.0.177:
IP 192.168.0.172.47596 > <mydestip>.5061
If it was a system/kernel issue, then why is the behavior different for TCP
and UDP? I thought that maybe the application does not request the bound
address as a source in case of TCP...


??, 13 ???. 2017 ?. ? 14:37, Joshua Colp <jcolp at digium.com>:
> On Mon, Mar 13, 2017, at 08:31 AM, Kseniya Blashchuk wrote:
> > Yes, look:
> > netstat -nlp | egrep '506[01]'
> > tcp        0      0 192.168.0.177:5061      0.0.0.0:*
> > LISTEN
> >      13255/asterisk
> > udp        0      0 192.168.0.177:5060      0.0.0.0:*
> >     13255/asterisk
> > Still, the problem is with *outgoing* *TCP* packets originated from
> > asterisk. Source IP is set to the first IP address of the interface
only
> > when TCP is used. As I understand, the application (chan_sip in this
> > case)
> > should request kernel to use the specific source IP address (used in
bind
> > directive) for outgoing packets, however it seems to be done only for
> > UDP.
> > For outgoing packets on TCP/5061 I see the following:
> > IP *192.168.0.172*.47596 > <mydestip>.5061: Flags [S], seq
2529313754
> <(252)%20931-3754>,
> > win
> > 29200, options [mss 1460,sackOK,TS val 82765588 ecr 0,nop,wscale 7],
> > length
> > 0
> > And with UDP as transport:
> > IP *192.168.0.177*.5060 > <mydestip>.5060: SIP: OPTIONS ....
>
> The underlying code does this already. It connects using the bound
> socket (which would be bound to the IP address you've provided). This
> should have the system use the source IP address as you want, but it's
> evidently not.
>
> --
> Joshua Colp
> Digium, Inc. | Senior Software Developer
> 445 Jan Davis Drive NW - Huntsville, AL 35806 - US
> Check us out at: www.digium.com & www.asterisk.org
>
> --
> _____________________________________________________________________
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On Mon, Mar 13, 2017, at 08:43 AM, Kseniya Blashchuk
wrote:
> Mmh sorry I'm afraid I did not understand your last message. Yes the
code
> does that but only with UDP, for TCP the source address is 192.168.0.172
> though it's bound to 192.168.0.177:
> IP 192.168.0.172.47596 > <mydestip>.5061
> If it was a system/kernel issue, then why is the behavior different for
> TCP
> and UDP? I thought that maybe the application does not request the bound
> address as a source in case of TCP...
The chan_sip module, from looking at the code, does use the bound
address when connecting. Someone would need to dig deeper to understand
if the problem is somehow in Asterisk or if it is the system somehow
doing it.

-- 
Joshua Colp
Digium, Inc. | Senior Software Developer
445 Jan Davis Drive NW - Huntsville, AL 35806 - US
Check us out at: www.digium.com & www.asterisk.org