2001-05-24 13:15:49 +00:00
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$FreeBSD$
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1998-12-15 19:05:35 +00:00
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This contains a couple of examples for using the portal filing system.
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The portal file system provides a way of obtaining a file descriptor
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to a filesystem object (i.e. something that is accessed by open(2),
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pipe(2), socket(2) or socketpair(2)) via the filesystem namespace.
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At present the only file descriptor supported are TCP sockets and
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files.
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NOTE!!!! The portal file system is experimental in nature and should
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not be considered secure, use with caution.
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First off mount the filesystem using something like:
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2001-05-24 13:15:49 +00:00
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# mount_portalfs /usr/share/examples/portal/portal.conf /p
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1998-12-15 19:05:35 +00:00
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Then you should be able to do things like
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# cat /p/tcp/localhost/daytime
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Sun Nov 22 17:50:09 1998
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(assuming inetd is running the daytime service, by default it is off)
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Welcome to FreeBSD!
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# mkdir -p /tmp/root
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# cd /tmp/root
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# mkdir bin p
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# cp /bin/sh /bin/cat bin
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2001-05-24 13:15:49 +00:00
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# mount_portalfs /usr/share/examples/portal/portal.conf /tmp/root/p
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1998-12-15 19:05:35 +00:00
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# chroot /tmp/root
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# pwd
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/
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# echo *
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bin p
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# cat /etc/motd
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cat: /etc/motd: No such file or directory
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# cat /p/fs/etc/motd
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FreeBSD 2.2.6-RELEASE (COMPUTER) #0: Sat Aug 22 17:11:37 BST 1998
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Welcome to FreeBSD!
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Finally, a very simple example of the listening server is available,
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fire up two xterms. In the first
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xterm-1$ cat /p/tcplisten/ANY/6666
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(the ANY is a wildcard just like using INADDR_ANY, any resolvable host
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can be used).
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In the second xterm
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xterm-2$ echo "hello there" >/p/tcp/localhost/6666
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You should see the "hello there" string appear on the first terminal.
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Unprivilged users can't create servers on privalged ports.
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xterm-1$ cat /p/tcplisten/ANY/666
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cat: /p/tcplisten/ANY/666: Operation not permitted
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but root can
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xterm-1# cat /p/tcplisten/ANY/666
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In the second
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xterm-2$ echo "hello there" >/p/tcp/localhost/666
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should produce the expected response.
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You can also swap the client/server read and write commands etc.
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