Date: Fri, 16 May 2008 13:45:12 +0300 From: Manolis Kiagias <sonicy@otenet.gr> To: Nikos Vassiliadis <nvass@teledomenet.gr> Cc: freebsd-questions@freebsd.org Subject: Re: Routing to internet addresses ending with 255 Message-ID: <482D65B8.8080301@otenet.gr> In-Reply-To: <200805161314.22978.nvass@teledomenet.gr> References: <482D54B3.3060306@otenet.gr> <200805161314.22978.nvass@teledomenet.gr>
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Nikos Vassiliadis wrote: > On Friday 16 May 2008 12:32:35 Manolis Kiagias wrote: > >> I had this weird problem today, and I would like to know what caused it: >> >> I have two home servers, on different locations, on two ADSL lines using >> dynamic DNS. One is running Debian, the other FreeBSD 7.0-RELEASE. >> >> I usually ssh from one to the other. Today, the debian server had a >> public (internet) IP ending in 255. The FreeBSD 7.0 system refused to >> communicate with it. Another 6.3 system had no problem. The 6.3 and 7.0 >> system have identical adsl routers. >> >> Trying a traceroute from 7.0, it would seem the debian system was one >> hop away, which is of course incorrect. >> >> I understand that x.x.x.255 is ethernet's broadcast address. >> > > No, it's not. Since these days IP is classless, a network > (and thus its broadcast address) is completely local information, > not known to remote hosts. What might look to an external observer > as a /24 network, may be something else. For example 213.0.0.255/24 > may be the broadcast address for net 213.0.0.0/24, but it's not the > broadcast address for net 213.0.0.0/23, which would be 213.0.1.255. > > Also, regadless of being the broadcast address or not, to the external > observer that address is just an IP address. The router of the network > will handle specially(will broadcast) the packet if it's destined for the > broadcast address. > > I guessed it would be like this. Thank you for clarifying it. >> However 6.3 >> had no problem connecting to it, while 7.0 would not. Has something >> changed in FreeBSD, is this the intended behaviour or a bug? >> > > This looks like a bug. Can you post more info about it? > > Problem is I've already reset the router that had the .255 address. All other actions had no effect: - Restarting the network interface in 7.0 - Restarting routing / erasing and reconfiguring routing table in 7.0 - Trying the IP address directly instead of the dyndns.org name (clearly not any type of DNS problem) - Restarting the router connected to 7.0 Traceroute gave a result like: traceroute xxx.dyndns.org traceroute to xxx.dyndns.org (xxx.xxx.xxx.255), 64 hops max, 40 byte packets 1 xxx.dyndns.org (xxx.xxx.xxx.255) 1.008 ms 1.084 ms 0.928 ms Clearly wrong, since everything goes through my router: traceroute www.otenet.gr traceroute to www.otenet.gr (62.103.128.215), 64 hops max, 40 byte packets 1 router (192.168.0.55) 1.014 ms 0.948 ms 0.941 ms 2 athe10kt-l1.otenet.net (62.103.129.42) 19.399 ms 20.362 ms 19.892 ms ...
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