Ubridge is great but...

In my last post I've talked about ubridge and how it's supposed to work with GNS3. The problem is that users generally need root permissions because GNS3 is basically creating a new (veth) interface on the host. You can't do this without some kind of special permission. Ubridge does this by using Linux capabilities and the setcap command. That's why when you do "make install" when installing ubridge you get:

sudo setcap cap_net_admin,cap_net_raw=ep /usr/local/bin/ubridge

Setting permissions on a file *once* is not a problem, ubridge is already used for VMware and this doesn't really conflict with how GNS3 works. So in GNS3 ubridge should create the veth interfaces for Docker, not GNS3. That's why the newest version of ubridge has some new cool features like hypervisor mode and creating and moving veth interfaces to other namespaces. Here's a quick example:

1. Start ubridge in hypervisor mode on port 9000:

./ubridge -H 9000

2. Connect in Telnet on port 9000 and ask ubridge to create a veth pair and move one interface to namespace of container

telnet localhost 9000
Trying 127.0.0.1...
Connected to localhost.
Escape character is '^]'
docker create_veth guestif hostif
100-veth pair created: guestif and hostif
docker move_to_ns guestif 29326

100-guestif moved to namespace 29326

3. Bridge the hostif interface to an UDP tunnel:

bridge create br0
100-bridge 'br0' created
bridge add_nio_linux_raw br0 hostif
100-NIO Linux raw added to bridge 'br0'
bridge add_nio_udp br0 20000 127.0.0.1 30000
100-NIO UDP added to bridge 'br0'
bridge start br0
100-bridge 'br0' started

That's the general idea of how it should work but I'm having some problems getting this to work on my Fedora installation in the docker branch. My mentors are being really helpful and are trying to debug this with me. I sent them the outputs from various components so here they are for you to get the wider picture.

Manual hypervisor check:

gdb) run -H 11111
Starting program: /usr/local/bin/ubridge -H 11111
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib64/libthread_db.so.1".
Hypervisor TCP control server started (port 11111).
Destination NIO listener thread for bridge0 has started
Source NIO listener thread for bridge0 has started
[New Thread 0x7ffff65b8700 (LWP 4530)]
[New Thread 0x7ffff6db9700 (LWP 4529)]
[New Thread 0x7ffff75ba700 (LWP 3576)]

GNS3 output:

bridge add_nio_linux_raw bridge0 gns3-veth0ext

bridge add_nio_udp bridge0 10000 127.0.0.1 10001

2015-08-01 13:11:22 INFO docker_vm.py:138 gcetusic-vroot-latest-1 has started

bridge add_nio_linux_raw bridge0 gns3-veth1ext

bridge add_nio_udp bridge0 10001 127.0.0.1 10000

2015-08-01 13:11:22 INFO docker_vm.py:138 gcetusic-vroot-latest-2 has started

Tcpdump output:

[cetko@nerevar gns3]$ sudo tcpdump -i gns3-veth0ext

tcpdump: verbose output suppressed, use -v or -vv for full protocol decode

listening on gns3-veth0ext, link-type EN10MB (Ethernet), capture size 262144 bytes

12:06:51.995942 ARP, Request who-has 10.0.0.2 tell 10.0.0.1, length 28

12:06:52.998217 ARP, Request who-has 10.0.0.2 tell 10.0.0.1, length 28

[cetko@nerevar gns3]$ sudo tcpdump -i gns3-veth1ext

tcpdump: verbose output suppressed, use -v or -vv for full protocol decode

listening on gns3-veth1ext, link-type EN10MB (Ethernet), capture size 262144 bytes

Netstat output:

udp        0      0 127.0.0.1:10000         127.0.0.1:10001         ESTABLISHED

udp        0      0 127.0.0.1:10001         127.0.0.1:10000         ESTABLISHED