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Re: Amcheck and amdump port usage?
2004-09-13 15:07:40
--On Monday, September 13, 2004 14:24 -0400 KEVIN ZEMBOWER
<KZEMBOWE AT jhuccp DOT org> wrote:
I'm still trying to troubleshoot my problem getting Amanda to work though
a firewall. I've read John Jackson's port usage document and the FAQ at
http://amanda.sourceforge.net/fom-serve/cache/139.html. I'd like someone
to comment on whether or not I have the overall communication sequence
correct below. Then, I'd like information on how this is different if
amcheck rather than amdump is run.
In compiling amanda, I used these options: "--with-portrange=10080,10083
--with-tcpportrange=10080,10083 --with-udpportrange=850,854".
This is what I understand concerning the sequence of port usage in making
an amanda backup:
1. The tapehost makes a 'start backup' request of the client, originating
on port 850-854 to port 10080-10083 using UDP. The contents of the packet
contain a port number in the range 850-854 which is open on the tapehost,
listening for TCP connections.
Your steps are pretty wrong so lets start over......
1. tapehost makes 'start backup, estimate/etc' call to amandad over UDP on
remote (usually 10080) client sends back response(s) to udp port
(udpportrange).
2. after response/receipt of estimates (Assuming backup run) at some point
later the server sends start backup, this packet contains a tcp port to
connect to on the server in the tcpportrange/portrange (these are the
same). the client may also connect to amandaidx on the tape server as well
to transmit indices at this time (I can't remember, and it does depend on
the index option in the dumptype config). Once connected the client begins
transmitting backup data to the server.
That's it, two (ish) step process. If it's a check request it just does a
test to see if it can get an estimate or backup by dispatching the
appropriate commands on the client side, then responding back to the
tapehost on the indicated UDP port (udpportrange). If it's going to be a
backup then further TCP connections will be made to the ports indicated
when the backup starts. For estimates they come back via UDP packets. No
TCP connections are made to udpportrange, and the server never connects to
the client.
The server doesn't tell the client to start backup until it's ready for
data to flow to it.
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