Will Mac OS X see an EMPEG (jEmplode) Using X-Over

Home network is setup wireless but I'd like the EMPEG to be wired using a Cross Over Cable (Cat 5) from the EMPEG to the Mac. Are there any limitations here or is it a simple process and jEmplode (.jar or the OS X specific version) will find it?

You'd have to specify an IP address on the Mac's ethernet port (which I assume is currently unused) and on the empeg, as there will be no facility for automatic address assignment. And I'd suggest going ahead and specifying the empeg's address within jEmplode rather than relying on broadcast scans working. (It might work with broadcasts, but I don't know how jEmplode determines the correct broadcast address and it might not select it properly, but since there's no detriment in specifying it, you might as well.)

I can see how there might be some problems with getting the Mac's ethernet port's autonegotiation of speed and duplexity working right, but you should be able to overcome those without much effort if they do crop up.

There have been a lot of interations of how broadcasting works in jEmplode ... Currently, I attempt to retrieve all the IP address that are assigned to your machine, and then go through each octet making a broadcast on each subnet (255.255.255.255, 192.255.255.255, 192.168.255.255, 192.168.1.255, etc). It seems to be pretty good these days about tracking down your Empeg. However, if the Empeg doesn't have a dynamically or statically assigned IP (i.e. just crossover w/o DHCP) then I'm not entirely sure what will happen, so it's definitely best statically assign it and set it in jEmplode.

The Mac autosensing crossover support is generally really good, so I think it will work fine.

ms

That must be why I had trouble with jEmplode's broadcasting sometimes. I have a network whose broadcast address is 192.168.2.128, so it wouldn't ever catch that one with that algorithm, would it?

I have a network whose broadcast address is 192.168.2.128

yikes. well... actually, assuming that jemplode can figure out the correct subnet mask, if your mask is 255.255.255.128, it should catch it, if i recall my CCNA readings. but if there isn't, jemplode might as well port some nmap routines to quickly syn ping the whole subnet. i also was reading something on /. few months back about "black ops in tcp/ip" where they wrote a program to find which ips had port 80 open... yeah, nothing new except they got the results of 65000 ips in 3 seconds.

The problem is that there is, IIRC, no portable way to determine netmasks or broadcast addresses or network addresses in any language. Under most Unices, SIOCGIFNETMASK would work, but I doubt that works under Windows, nor do I know if Java has any such ioctl construct.

something on /. few months back about "black ops in tcp/ip"

Link for anyone interested: http://slashdot.org/article.pl?sid=02/11/18/2032225&mode=flat&tid=172

/Michael

Yep -- This is the root of the problem... With a "weird" netmask, jEmplode would have no idea (that I know of, anyway) to detect it. This is definitely not my bag, though, so if someone knows of a way in Java to do this reliably, I'm all ears.... 1.4 has a much slicker way to enumerate interfaces -- I wonder if it has a getBroadcastAddress() on it? Even if it did, though, I'd have to still have a fallback mechanism for 1.1 VM's. Mike

Currently, I attempt to retrieve all the IP address that are assigned to your machine, and then go through each octet making a broadcast on each subnet (255.255.255.255, 192.255.255.255, 192.168.255.255, 192.168.1.255, etc).

FWIW, it still doesn't work in all scenarios. My server running FreeBSD with 2 NICs can never find the empeg. But that config is pretty funky, the 'outside' NIC has a static bogus address (192.168.0.1) and a dynamically assigned real address doing PPPoE. The inner interface has another static non-routable address (192.168.101.254). There is also a virtual interface used for a VPN with a third non-routable IP. So four IP's total several of which have firewall rules applied to them and two of which are doing NAT just to make it a little more complicated. All the all the netmasks are .255s though so your search routine should work AFAIK. I have been meaning to ask you for a while if you could add an option to specify a network or at least interface to search.

-Mike