# WTF: ping enables rsync?!

## psycho

Very weird. I guess something (a file somewhere?) that changes when a network connection is established is the key to it. Basically, I use grsync to sync different machines. It runs rsync through ssh (and over an encrypted wireless network using wpa_supplicant). Works perfectly well, but only after I ping one of the hosts from the other. Before that, it fails to connect. After a ping (which works no problems), suddenly grsync works. Fairly consistently reproducible, but not 100% (occasionally it just works without pinging, maybe because other things have done whatever ping is doing...and yes, I've allowed plenty of time for wpa_supplicant to connect, so it's not just the additional delay while I launch a console and run ping...this happens even 20 minutes or more after firing up the network on the laptop).

Any ideas? Scripting a quick ping into grsync's launcher would be fine as a workaround, but seriously, that shouldn't be necessary, right?

[Edit]: Never mind, I'm being lazy asking here before trawling all the logs...but let me know if there's an obvious answer.

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## gerdesj

Do you have a funky firewall setup somewhere that blocks many things and stop ARP from working but allows ICMP and hence ARP is also then able to work?

Before pinging and after trying rsync initially, check the output of #arp -a  - do you see the MAC and IP addresses of the remote systems?

Cheers

Jon

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