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Hello,

by default the kernel will choose the first IP address building the IP
header, that's correct. But imho the programmer is able to set explicitly the
source IP address by choosing i.e. the IP_HDRCINCL option. So he is able to
set the values he want to use due to now he is responsible creating the IP
header(and not the kernel). Especially due to the fact that we use a raw
socket in sctplib.
I expected that the sctplib has to do so. On the receiving side the
destination address is retrieved I saw. So is it possible to implement
setting of the source address for send events?

Best regards,

DTepelmann

Andreas Jungmaier
<ajung AT exp-math.uni-essen.de>
schrieb am 13.05.04 11:21:46:
>
> -----BEGIN PGP SIGNED MESSAGE-----
> Hash: SHA1
>
> On Mittwoch, 12. Mai 2004 20:57, you wrote:
> > Hi,
> >
> > I got to a point where I'm get confused. Hope you can help.
> >
> > I have adjust a second IP address for eth0 in
> > /etc/sysconfig/network/ifcfg-eth0: ...
> > BROADCAST='192.168.89.255'
> > IPADDR='192.168.89.84'
> > NETMASK='255.255.255.0'
> > IPADDR2='192.168.89.22'
> > NETMASK2='255.255.255.0'
> > NETWORK='192.168.89.0'
> >
> > So I'm able to connect to my machine with 192.168.89.84 or with
> > 192.168.89.22. It's working fine. Reason of this was to test several SCTP
> > association between 2 SCTP instances on to different machines. But I got
> > in
> > trouble. All packets(INIT's) send to x.x.x.22 will replied via x.x.x.84,
> > which causes an SCTP Abort at the initiator side. This behaviour can
> > easyly
> > reproduced with mini_ulp(./mulp -s 192.168.89.70 -l 10002 -d 192.168.89.22
> > -r 7) vs. echo_server(./echo_server -s 192.168.89.22 -V).
> >
> > How is it handled in sctplib, or is it a bug? Something wrong on my side?
> > How it's possible to handle more than one local address?
>
>
> This is a known problem with multiple addresses that the linux kernel
> assigns to one interface. ALL outgoing packets usually have as source
> address the main (or first) configured IP address.
>
> You can only avoid problems, if you list all local addresses, or specify
> "-s 0.0.0.0" so that all local addresses are contained in the outgoing INIT
> and INIT-ACK chunks (this is the logical address INADDR_ANY).
>
> So: more than one local address is not a problem....also you can try to
> activate IPv6 by doing "modprobe ipv6" as root.
>
> Then recompile the library, and have fun playing with IPv6...
>
> Andreas
>
> - --
> Dipl.-Ing. Andreas Jungmaier
> Computer Networking Technology Group
> University of Duisburg-Essen
> http://www.exp-math.uni-essen.de/~ajung
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• [SCTP-Discussion] Multihoming, DTepelmann, 05/12/2004
  • Re: [SCTP-Discussion] Multihoming, Andreas Jungmaier, 05/13/2004
  • <Possible follow-up(s)>
  • Re: [SCTP-Discussion] Multihoming, DTepelmann, 05/14/2004
    • Re: [SCTP-Discussion] Multihoming, Michael Tuexen, 05/14/2004

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