Dynamic Uml Mesh Modeler » History » Version 1
Martin Willi, 26.07.2007 11:34
| 1 | 1 | Martin Willi | = Dynamic Uml Mesh Modeler = |
|---|---|---|---|
| 2 | 1 | Martin Willi | ''Dumm'' is a framework to set up a virtual network using user mode linux guests. |
| 3 | 1 | Martin Willi | It cleverly glues together some nice technologies to build networks dynamically. |
| 4 | 1 | Martin Willi | To change the network topology, hosts are not required to reboot, changes apply |
| 5 | 1 | Martin Willi | instantly and configuration can be done on the host (no network connection |
| 6 | 1 | Martin Willi | required to change anything). |
| 7 | 1 | Martin Willi | |
| 8 | 1 | Martin Willi | == Status == |
| 9 | 1 | Martin Willi | ''Dumm'' is currently in [source:trunk/src/dumm heavy development] and incomplete. A prototype is running |
| 10 | 1 | Martin Willi | and a proof of concept has shown that it works. |
| 11 | 1 | Martin Willi | Along with the ''dumm'' library, a console client is developed to interactively set |
| 12 | 1 | Martin Willi | up and reconfigure UML networks. A test framework for strongSwan is planned around |
| 13 | 1 | Martin Willi | it, and a neat GTK GUI to click together your UML network would be just lovely (someone?). |
| 14 | 1 | Martin Willi | |
| 15 | 1 | Martin Willi | == Terminology == |
| 16 | 1 | Martin Willi | * Host |
| 17 | 1 | Martin Willi | * The machine you are working on, has virtual guests in it. Mostly |
| 18 | 1 | Martin Willi | runs on bare hardware (unless you do really fancy stuff). |
| 19 | 1 | Martin Willi | * Guest |
| 20 | 1 | Martin Willi | * Virtual UML machine running on the host. |
| 21 | 1 | Martin Willi | |
| 22 | 1 | Martin Willi | == Why UML? == |
| 23 | 1 | Martin Willi | UML is a senior in vitualization technologies, and there is a lot of new |
| 24 | 1 | Martin Willi | hyped stuff about virtualization around. However, UML is lightweight, easy to |
| 25 | 1 | Martin Willi | set up and allows dynamic reconfiguration (e.g. add/remove innterfaces at |
| 26 | 1 | Martin Willi | runtime), allows access to the hosts filesystem through hostfs and has some |
| 27 | 1 | Martin Willi | other neat features. |
| 28 | 1 | Martin Willi | Performance is not critical for our needs, and maybe we get hardware |
| 29 | 1 | Martin Willi | virtualization support soon in UML. |
| 30 | 1 | Martin Willi | It is free and fits perfectly. |
| 31 | 1 | Martin Willi | |
| 32 | 1 | Martin Willi | == Requirements == |
| 33 | 1 | Martin Willi | * Host: |
| 34 | 1 | Martin Willi | * Kernel: |
| 35 | 1 | Martin Willi | * A recent 2.6 kernel |
| 36 | 1 | Martin Willi | * [http://www.user-mode-linux.org/~blaisorblade/patches/skas3-2.6/ SKAS3 patch] highly recommended |
| 37 | 1 | Martin Willi | * [http://fuse.sourceforge.net/ FUSE] enabled |
| 38 | 1 | Martin Willi | * support for TAP devices |
| 39 | 1 | Martin Willi | * Userland: |
| 40 | 1 | Martin Willi | * [source:trunk/src/libstrongswan libstrongswan] |
| 41 | 1 | Martin Willi | * [http://tiswww.case.edu/php/chet/readline/rltop.html libreadline] |
| 42 | 1 | Martin Willi | * libbridge from [http://linux-net.osdl.org/index.php/Bridge bridge-utils] |
| 43 | 1 | Martin Willi | * [http://podgorny.cz/moin/UnionFsFuse unionfs-fuse] |
| 44 | 1 | Martin Willi | * Guest: |
| 45 | 1 | Martin Willi | * Kernel: |
| 46 | 1 | Martin Willi | * hostfs |
| 47 | 1 | Martin Willi | * consoles? |
| 48 | 1 | Martin Willi | * Userland: |
| 49 | 1 | Martin Willi | * ip (from iproute2)/netlink proxy? |
| 50 | 1 | Martin Willi | |
| 51 | 1 | Martin Willi | == Architecture == |
| 52 | 1 | Martin Willi | |
| 53 | 1 | Martin Willi | === Working set === |
| 54 | 1 | Martin Willi | Dumm needs a directory to store all its files, guest configurations and other |
| 55 | 1 | Martin Willi | stuff. Inside that working directory, you'll find: |
| 56 | 1 | Martin Willi | |
| 57 | 1 | Martin Willi | {{{ |
| 58 | 1 | Martin Willi | workingdir/ |
| 59 | 1 | Martin Willi | host/ |
| 60 | 1 | Martin Willi | alice/ |
| 61 | 1 | Martin Willi | bob/ |
| 62 | 1 | Martin Willi | mount/ |
| 63 | 1 | Martin Willi | alice/ |
| 64 | 1 | Martin Willi | bob/ |
| 65 | 1 | Martin Willi | run/ |
| 66 | 1 | Martin Willi | alice/ |
| 67 | 1 | Martin Willi | bob/ |
| 68 | 1 | Martin Willi | master/ |
| 69 | 1 | Martin Willi | linux |
| 70 | 1 | Martin Willi | }}} |
| 71 | 1 | Martin Willi | ''linux'' is the default UML guest kernel. You may symlink it here, but you may |
| 72 | 1 | Martin Willi | define other (and different) kernels when creating guests. |
| 73 | 1 | Martin Willi | ''master'' is the read-only master filesystem which contains a common set of |
| 74 | 1 | Martin Willi | files for all guests. Guests use this directory as copy-on-write root |
| 75 | 1 | Martin Willi | filesystem. |
| 76 | 1 | Martin Willi | ''host'' contains the individual host files. It is a unionfs overlay over the |
| 77 | 1 | Martin Willi | ''master'' directory. The unionfs is mounted into the guests ''mount'' directory. |
| 78 | 1 | Martin Willi | Changes on the guest will go into it's ''host'' directory. |
| 79 | 1 | Martin Willi | ''run'' contains runtime information for each guest, such as consoles, PIDs and |
| 80 | 1 | Martin Willi | logfiles. |
| 81 | 1 | Martin Willi | So if you want to edit a guests files, do it in it's ''mount'' directory. Changes |
| 82 | 1 | Martin Willi | will be written to ''host'', but this is transparently to you. |
| 83 | 1 | Martin Willi | |
| 84 | 1 | Martin Willi | === Networking === |
| 85 | 1 | Martin Willi | Network connectivity is realized through tap devices. When creating a ''eth0'' |
| 86 | 1 | Martin Willi | network device on ''alice'', a ''alice-eth0'' tap device appears on the host. These |
| 87 | 1 | Martin Willi | are directly connected, when ''alice'' sends traffic to ''eth0'', it appears on the |
| 88 | 1 | Martin Willi | host at ''alice-eth0''. You can see that as a small network segment (or just a |
| 89 | 1 | Martin Willi | cable), where these interfaces are attached directly. |
| 90 | 1 | Martin Willi | To build larger network segments, linux bridging on the host comes into play. |
| 91 | 1 | Martin Willi | Segments are created by creating a bridge (as with brctl), and then attaching |
| 92 | 1 | Martin Willi | our tap devices to that bridge. Routing can be done on a UML guest, or even on |
| 93 | 1 | Martin Willi | the host. |
| 94 | 1 | Martin Willi | This setup has some advantages over the ''uml_switch'' solution. Bridging works |
| 95 | 1 | Martin Willi | more reliable in the kernel, and as we see every network interface on the host, |
| 96 | 1 | Martin Willi | we can sniff at every interface to get some clue what the guests are doing. |
| 97 | 1 | Martin Willi | |
| 98 | 1 | Martin Willi | == Howto == |
| 99 | 1 | Martin Willi | |
| 100 | 1 | Martin Willi | === Host setup === |
| 101 | 1 | Martin Willi | |
| 102 | 1 | Martin Willi | === Guest setup === |
| 103 | 1 | Martin Willi | |
| 104 | 1 | Martin Willi | === Sample session === |