GGSN p-t-p address?

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Keith keith at rhizomatica.org
Thu Aug 23 10:47:38 UTC 2018



On 22.08.2018 18:55, Martin Hauke wrote:
>
> If the remote P-t-P IP address cannot be determined via IPCP pppd is
> using fallback IP addresses.
>
> The IP address pppd then uses is 0x0a404040 + a interface unit id.
> The interface unit id is "0" for ppp0, "1" for ppp1, ...
>
> The resulting (fake) fallback P-t-P remote IP addresses are
>
>   ppp0 -> 10.64.64.64
>   ppp1 -> 10.64.64.65
> For more details see:
> https://github.com/paulusmack/ppp/blob/5c765a67fd25f9d84e71ed61ace37c8c97f6be15/pppd/ipcp.c#L1752
Interesting! But I note the code there is:

    if (wo->hisaddr == 0 && !noremoteip) {
        /* make up an arbitrary address for the peer */
        wo->hisaddr = htonl(0x0a707070 + ifunit);

wo->hisaddr being the p-t-p side, so the IP should be 10.112.112.112 in
that case, no?

Ah.. no.. reading further down in the next function:

https://github.com/paulusmack/ppp/blob/5c765a67fd25f9d84e71ed61ace37c8c97f6be15/pppd/ipcp.c#L1812

To try to bring this back on topic for the list, I still have the
question of whether the GGSN /could/ in fact provide the correct p-t-p
address?







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