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