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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