[CentOS] Problem with DHCP and default route in CentOS

Joshua J. Kugler

joshua at azariah.com
Wed Aug 21 21:48:02 UTC 2013


I have a CentOS 6.4 VM that is getting its DHCP information from dnsmasq (a 
libvirt instance). However, it is not applying the routing information.  
Attached is a tcpdump of the dhcpc output. You'll see:

            Default-Gateway Option 3, length 4: 192.168.122.1

However, when I run 'route -n', I get:

# route -n
Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
192.168.122.0   0.0.0.0         255.255.255.0   U     0      0        0 eth0
169.254.0.0     0.0.0.0         255.255.0.0     U     1002   0        0 eth0

Any ideas as to why the default route/gateway information isn't being applied?

j


-- 
Joshua J. Kugler - Fairbanks, Alaska
Azariah Enterprises - Programming and Website Design
joshua at azariah.com - Jabber: pedahzur at gmail.com
PGP Key: http://pgp.mit.edu/  ID 0x73B13B6A
-------------- next part --------------
14:52:48.824645 IP (tos 0x10, ttl 128, id 0, offset 0, flags [none], proto UDP (17), length 338)
    0.0.0.0.bootpc > 255.255.255.255.bootps: [udp sum ok] BOOTP/DHCP, Request from 52:54:00:93:ff:ac, length 310, xid 0x23b2de1d, Flags [none] (0x0000)
          Client-Ethernet-Address 52:54:00:93:ff:ac
          Vendor-rfc1048 Extensions
            Magic Cookie 0x63825363
            DHCP-Message Option 53, length 1: Request
            Requested-IP Option 50, length 4: 192.168.122.3
            Parameter-Request Option 55, length 13: 
              Subnet-Mask, BR, Time-Zone, Classless-Static-Route
              Domain-Name, Domain-Name-Server, Hostname, YD
              YS, NTP, MTU, Option 119
              Default-Gateway
            Vendor-Class Option 60, length 43: "anaconda-Linux 2.6.32-358.el6.x86_64 x86_64"
14:52:48.825900 IP (tos 0x0, ttl 64, id 65407, offset 0, flags [none], proto UDP (17), length 335)
    192.168.122.1.bootps > 192.168.122.3.bootpc: [bad udp cksum 44a1!] BOOTP/DHCP, Reply, length 307, xid 0x23b2de1d, Flags [none] (0x0000)
          Your-IP 192.168.122.3
          Server-IP 192.168.122.1
          Client-Ethernet-Address 52:54:00:93:ff:ac
          Vendor-rfc1048 Extensions
            Magic Cookie 0x63825363
            DHCP-Message Option 53, length 1: ACK
            Server-ID Option 54, length 4: 192.168.122.1
            Lease-Time Option 51, length 4: 3600
            RN Option 58, length 4: 1800
            RB Option 59, length 4: 3150
            Subnet-Mask Option 1, length 4: 255.255.255.0
            BR Option 28, length 4: 192.168.122.255
            Default-Gateway Option 3, length 4: 192.168.122.1
            Domain-Name-Server Option 6, length 4: 192.168.122.1
            Hostname Option 12, length 13: "datacollector"


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