ΤΖΩΤΖΙΟΥ's questions

At the office we have a server with a single $SERVER_IF having a local IP address $SERVER_IP_MAIN=192.168.1.12/24 behind an ADSL router $ROUTER_MAIN with a static external IP address from $ISP_MAIN. Everything works fine, incoming and outgoing connections pass through without any issues.

Now, we got another connection to a different $ISP_BACKUP for fallback purposes using $ROUTER_BACKUP. I don't need any load balancing; all outgoing connections should still go through $ISP_MAIN, I just want to ensure that any incoming connections through $ISP_BACKUP are routed through $ROUTER_BACKUP.

I tried to follow some generic advice using ip route and ip rule, but I must be doing something wrong. (My main source: http://lartc.org/howto/lartc.rpdb.multiple-links.html )

The current setup is as follows:

server has:
    $SERVER_IF=eth0 with address $SERVER_IP_MAIN=192.168.1.12/24
    $SERVER_IF:0=eth0:0 with address $SERVER_IP_BACKUP=192.168.252.12/24 # pseudo interface

$ROUTER_MAIN has:
    $ROUTER_MAIN_IP=192.168.1.254/24

$ROUTER_BACKUP has:
    $ROUTER_BACKUP_IP=192.168.252.1/24

Using tcpdump on the server, I verified that $ROUTER_BACKUP is set-up correctly since packets coming through $ISP_BACKUP are being delivered to $SERVER_IP_BACKUP, but I assume that the replies are being routed through $ISP_MAIN because I can't establish a connection from an external server:

12:54:06.950853 IP 178.128.57.39.dsl.dyn.forthnet.gr.57987 > 192.168.252.12.5631: Flags [S], seq 2240370501, win 5840, options [mss 1452,sackOK,TS val 471912856 ecr 0,nop,wscale 4], length 0
12:54:06.950903 IP 192.168.252.12.5631 > 178.128.57.39.dsl.dyn.forthnet.gr.57987: Flags [S.], seq 2209117020, ack 2240370502, win 14480, options [mss 1460,sackOK,TS val 215023497 ecr 471912556,nop,wscale 4], length 0

Note that $ROUTER_BACKUP does not do a SNAT, since the server receives packets with the original outside-world source IP address.

How can I implement what is needed? (i.e. connections through $ISP_BACKUP to be routed through $ROUTER_BACKUP)

I have set up a virtual machine running Windows XP on my Ubuntu laptop. Using the virt-manager GUI application, I can insert a CD in my drive and go to Details→IDE CDROM 1 and click on the Connect button. Then the CD becomes available in my virtual machine.

How can I do the same through the command line? Obviously, I'd like to be able to disconnect from the command line too.

Note: I can start the VM from the command line using virsh start testbed (testbed being the name of the domain/VM).

I have a long running process on a server running Ubuntu Server 9.10. I would like to make it run under the SCHED_IDLE policy using the chrt command. However, after reading the man page, I can't manage to understand the proper way to issue the command for a running process.

I've tried unsuccessfully:

# chrt -i -p 688
pid 688's current scheduling policy: SCHED_OTHER
pid 688's current scheduling priority: 0
# chrt -p -i 688
pid 688's current scheduling policy: SCHED_OTHER
pid 688's current scheduling priority: 0
# chrt -p 688 -i
chrt: failed to set pid 0's policy: Invalid argument

I'll keep trying, but do you know how to do what I want?

It seems every version of Ubuntu has a different way to enable remote connections to the local X server.

I'm asking this question, while I do my own research: how can I enable the X server listening to TCP port 6000 on my machine, thus allowing remote X clients to connect to said port and use my display?