Xdg's questions

Running Debian 10 Buster image (created with build-openstack-debian-image --release buster) with cloud-init image created by cloud-localds -v --disk-format raw --filesystem iso9660 --network-config=network-config-v2.yaml seed.img user-data.yaml.

Problem is that boot is delayed by waiting for DHCP, although I have a valid network configuration and it's applied after this delay.

[    3.619937] cloud-init[210]: Cloud-init v. 20.2 running 'init-local' at Sun, 10 Jan 2021 10:50:20 +0000. Up 3.40 seconds.
[  OK  ] Started Initial cloud-init job (pre-networking).
[  OK  ] Reached target Network (Pre).
         Starting Raise network interfaces...
[  OK  ] Started ifup for eth0.
[     *] A start job is running for Raise network interfaces (35s / 5min 1s)

What can I do to skip this delay?

I can provide more info if needed. Thanks.

# systemd-analyze blame
     1min 2.639s networking.service
           951ms cloud-init-local.service
           773ms cloud-init.service
           657ms cloud-final.service
           540ms cloud-config.service
           421ms dev-vda1.device
           310ms ifupdown-pre.service

My network-config-v2.yaml:

version: 2
renderer: networkd
ethernets:
  eth0:
    match:
      name: e*
    addresses:
      - private.ipv4/24
      - public.ipv4/32
      - ipv6/64
    gateway4: private.ipv4
    routes:
      - to: 0.0.0.0/0
        via: private.ipv4
    gateway6: ipv6
    nameservers:
      addresses:
        - ipv4
        - ipv6
      search: [domain.com]

I would like to use two mailservers for loadbalancing/failover - so one receives an e-mail and rewrites e-mail address with postsrsd. Then response to that e-mail is received with second mail server and this server needs to know, what was the original rewritten address so he can send the response e-mail to it. But this information is only on first original mail server.

How can I synchronize (and merge) postsrsd "database" to another machine?

Is it sufficient to set same /etc/postsrsd.secret key on both machines and will it work?

I've created ZFS datasets and installed virtual servers into them. Suddenly my ZFS volume free space is gone, but not all space is used in each dataset. I want to introduce thin provisioning (use ZFS sparse volume).

Is it possible to convert datasets into sparse volumes without deleting them? Thanks.

I'm using Postfix as a main MX server, connected to internet. On LAN I have MS Exchange, not accessible from internet.

Postfix works fine with virtual mailboxes, Dovecot for POP3/IMAP etc. I'm using catch-all virtual_alias_maps - have @mydomain.cz -> [email protected].

I want to forward mails for specific recipient addresses to Exchange server. Normally it's done with transport_maps, but when I use catch-all virtual alias, mail is sent to [email protected] and not processed with transport_maps.

Is it possible to use transport_maps with catch-all virtual_alias_maps?

Interesting parts of Postfix configuration:

transport_maps = mysql:/etc/postfix/mysql-virtual-transports.cf
virtual_alias_maps = mysql:/etc/postfix/mysql-virtual-alias-maps.cf
virtual_gid_maps = static:5000
virtual_mailbox_domains = mysql:/etc/postfix/mysql-virtual-mailbox-domains.cf
virtual_mailbox_maps = mysql:/etc/postfix/mysql-virtual-mailbox-maps.cf
virtual_transport = dovecot
virtual_uid_maps = static:5000

MySQL .cf files:

query = SELECT password FROM virtual_users WHERE email='%u' LIMIT 1
query = SELECT destination FROM virtual_aliases WHERE source='%s'
query = SELECT 1 FROM virtual_domains WHERE name='%s'
query = SELECT 1 FROM virtual_users WHERE email='%s'

table = transport
select_field = transport
where_field = domain
additional_conditions = and active = '1'

I have a Java web application, which runs from JAR, starts embedded Tomcat and is using Spring Boot.

Problem is that it runs very slow when running in KVM virtual guest. The same application in the same JDK (Java(TM) SE Runtime Environment (build 1.8.0_72-b15) Java HotSpot(TM) 64-Bit Server VM (build 25.72-b15, mixed mode) is starting 8 secs on bare metal, but 40 seconds when in virtualized system. Both OSes are Ubuntu 15.10 (kernel 4.2.0-27-generic). And that's not only starting issues, application responds very lazy for every HTTP request.

I've tried to change Java settings about SecureRandom, but nothing has changed.

-Djava.security.egd=file:///dev/urandom

SecureRandom and random entropy in virtual guests: https://security.stackexchange.com/questions/14386/what-do-i-need-to-configure-to-make-sure-my-software-uses-dev-urandom

https://stackoverflow.com/questions/137212/how-to-solve-performance-problem-with-java-securerandom

But it didn't help me. Do you have some other recommends, what to do? Thank you.

My virtual host is a new server with plenty of RAM, SSDs.. so I'm quite sure there is no hardware issue. I'm also running other KVM virtual guests and no problem at all. Only with slow Java application.

I'm using PowerDNS instance to serve my own domains. All clients in my network are using this DNS server.

How can I configure PowerDNS to query my ISP's DNS servers (for that domains that I don't know)? Is this the right way?

recursor=8.8.8.8:53
allow-recursion=10.0.0.0/8

Is it possible to specify multiple DNS servers? For example 8.8.8.8 and 8.8.4.4.

How to backup running KVM guests, when using qcow2 disks and host system does not use a LVM? Is it even possible without guest shutdown?

I have some records in bind for my DNS zone. Now I want to configure Samba4 Active Directory which wants to add some dynamic records into my zone. So I include /var/lib/samba/private/named.conf in my /etc/bind/named.conf. Problem is that same zone is defined statically and dynamically. It leads to error:

named[8992]: generating session key for dynamic DNS
named[8992]: sizing zone task pool based on 24 zones
named[8992]: Loading 'AD DNS Zone' using driver dlopen
named[8992]: samba_dlz: started for DN DC=myzone,DC=cz
named[8992]: samba_dlz: starting configure
named[8992]: samba_dlz: Failed to configure zone 'myzone.cz'
named[8992]: loading configuration: already exists
named[8992]: exiting (due to fatal error)
named[8992]: samba_dlz: shutting down

named.conf:

view "internal" {
  zone "myzone.cz" {
              type master;
              file "/etc/bind/zones/internal/myzone.cz.db";
  };
  include "/var/lib/samba/private/named.conf";
}

/var/lib/samba/private/named.conf:

dlz "AD DNS Zone" {
    # For BIND 9.9.0
        database "dlopen /usr/lib/x86_64-linux-gnu/samba/bind9/dlz_bind9_9.so";
};

How should I configure that to have static and Samba-dynamic DNS records? Thanks.

I want to synchronize MIT Kerberos database from master to slave, which is in a different geographical location. kprop synchronization fails because of a NAT. Is there any solution to have kprop working? Except VPN and manual database copy with SSH.

Thanks.

I'm have a Windows 7 installed as a KVM guest on Ubuntu Server 14.04 (headless server). Virtio driver is installed (for system disk). Graphics performance is bad due to lack of graphics driver - there is only a "standard VGA adapter" in a Device manager.

Does any "Guest additions" exist for KVM and Windows (7/8)? Is it possible to use Aero on KVM? I want to use RDP, but if VNC is good enough to support graphic effects, I don't care.

VM create command:

virt-install --connect qemu:///system --name win7develop --ram 8192 --vcpus 2 --disk path=sysdisk.qcow2,format=qcow2,bus=virtio,cache=none --boot hd --network=bridge:br0,model=e1000 --vnc --vncport=5900 --video=qxl --os-type=windows --os-variant=win7 --noautoconsole --accelerate --noapic --arch x86_64

Host CPU is Intel(R) Xeon(R) CPU E3-1246 v3 @ 3.50GHz (integrated graphics).