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RFC 3330 describes - This is the "link local" block.  It is allocated for
communication between hosts on a single link.  Hosts obtain these
addresses by auto-configuration, such as when a DHCP server may not
be found.

I don't want that so I explicitly disable it everywhere:

All files called /etc/sysconfig/network-scripts/ifcfg-* get this extra line:



My new server only has 1 physical network interface. So I configure 3 VLANs on my Switch:

  • 1
    The internal desktop systems (and printer, and media system, and ...)
  • 42
    This is intended for the systems that provide services to the outside world.
  • 666
    The outside (evil) connection that only has my ADSL modem and my firewall in it.


Setting up a VLAN interface is easy in CentOS, when you finally figure out how to do it.

You simply create a file like this for each VLAN interface.


# VLAN 42: Externally visible servers


I wanted to setup a 'dailup' network for my PDA so I can quickly check the traffic website without having to startup my desktop system.

This is just the summary of all the configuration files I created/changed.


When the interface comes up it needs and IP address. This is what the fragment relevant for this looks like in my situation.

# DHCP Server Configuration file.
ddns-update-style none;
option domain-name "";
option domain-name-servers;

default-lease-time 600;
max-lease-time 7200;
log-facility local7;

subnet netmask {
  option domain-name-servers;
  option domain-name "";
  option routers;
  option broadcast-address;
  default-lease-time 600;
  max-lease-time 7200;




PANDARGS='--listen --master --encrypt --auth --role NAP --devup /etc/bluetooth/pan/dev-up'




Make sure:  chmod 755 /etc/bluetooth/pan/dev-up

Note that this script needs work to set the correct security measures. This is a working test setup that simply gives the bluetooth access to my local LAN.

echo 1 > /proc/sys/net/ipv4/ip_forward
ifup bnep0
ip addr add dev bnep0
ip link set bnep0 up
iptables -t nat -A POSTROUTING -s -j MASQUERADE
iptables -A FORWARD -i bnep0 -o eth0.1 -j ACCEPT
iptables -A FORWARD -o bnep0 -i eth0.1 -j ACCEPT
service dhcpd restart


# HCI daemon configuration file.

# HCId options
options {
        # Automatically initialize new devices
        autoinit yes;

        # Security Manager mode
        #   none - Security manager disabled
        #   auto - Use local PIN for incoming connections
        #   user - Always ask user for a PIN
        security auto;

        # Pairing mode
        #   none  - Pairing disabled
        #   multi - Allow pairing with already paired devices
        #   once  - Pair once and deny successive attempts
        pairing multi;

        # Default PIN code for incoming connections
        passkey "1234"; # Not my real passkey :)

# Default settings for HCI devices
device {
        # Local device name
        #   %d - device id
        #   %h - host name
        # name "%h-%d";
        name "My Network";

        # Local device class
        #class 0x120104;
        #class 0x3e0100;
        class 0x920300; # Bit 8: Information (WEB-server, WAP-server, ...)
                        # Bit 5: Object Transfer (v-Inbox, v-Folder, ...)
                        # Bit 2: Networking (LAN, Ad hoc, ...)
                        # 0x03: LAN /Network Access point

        # Default packet type
        #pkt_type DH1,DM1,HV1;

        discovto 0;

        # Inquiry and Page scan
        iscan enable; pscan enable;

        # Default link mode
        #   none   - no specific policy
        #   accept - always accept incoming connections
        #   master - become master on incoming connections,
        #            deny role switch on outgoing connections
        lm master;

        # Default link policy
        #   none    - no specific policy
        #   rswitch - allow role switch
        #   hold    - allow hold mode
        #   sniff   - allow sniff mode
        #   park    - allow park mode
        lp rswitch,hold,sniff,park;

        # Authentication and Encryption (Security Mode 3)
        auth enable;
        encrypt enable;

Starting up

Final commands to enable it all:

chkconfig bluetooth on
chkconfig hidd on
chkconfig pand on
service bluetooth restart
service hidd restart
service pand restart

Now I can use my PDA and connect to the internet :)

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« March 2018 »