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Bug 756759

Summary: dhclient retries on DHCPDECLINE despite -1 option
Product: Red Hat Enterprise Linux 6 Reporter: Jiri Popelka <jpopelka>
Component: dhcpAssignee: Jiri Popelka <jpopelka>
Status: CLOSED ERRATA QA Contact: Release Test Team <release-test-team-automation>
Severity: medium Docs Contact:
Priority: medium    
Version: 6.1CC: hannsj_uhl, jnevill, ljozsa, mganisin, ovasik
Target Milestone: rcKeywords: Patch
Target Release: ---   
Hardware: All   
OS: Linux   
Whiteboard:
Fixed In Version: dhcp-4.1.1-27.P1.el6 Doc Type: Bug Fix
Doc Text:
Story Points: ---
Clone Of: 756490 Environment:
Last Closed: 2012-06-20 12:43:46 UTC Type: ---
Regression: --- Mount Type: ---
Documentation: --- CRM:
Verified Versions: Category: ---
oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
Embargoed:
Bug Depends On: 756490    
Bug Blocks: 1311427    
Attachments:
Description Flags
Send DHCPDECLINE and exit(2) when duplicate address has been detected and dhclient was started with '-1'. none

Description Jiri Popelka 2011-11-24 13:13:24 UTC 
+++ This bug was initially created as a clone of Bug #756490 +++

Description of problem:
When dhclient is invoked with the "-1" command line option, and then issues a DHCPDECLINE message it continues to try to obtain a lease. Despite the fact that "-1" should "Try to get a lease once. On failure exit with code 2." (from man page)


Version-Release number of selected component (if applicable):
dhclient-3.0.5-21.el5


How reproducible:
Consistently at customer


Steps to Reproduce:
1. Configure a DHCP server to hand out an IP address to clientA.
2. Statically configure clientB with that same IP address.
3. Run 'dhclient -1 -cf /tmp/dhcp.conf -pf /var/run/dhclient.pid -lf /var/lib/dhclient/dhclient.leases eth0' on clientA.
  

Actual results:
ClientA detects the duplicate IP address, issues a DHCPDECLINE message, and then continues to try and get a new IP address over and over again, despite the "-1" command line option.


Expected results:
ClientA detects the duplicate IP address, issues a DHCPDECLINE message, and then stops trying to obtain a lease.
Comment 1 Jiri Popelka 2011-11-24 13:14:44 UTC 
Created attachment 535897 [details]
Send DHCPDECLINE and exit(2) when duplicate address has been detected and dhclient was started with '-1'.
Comment 5 Ladislav Jozsa 2012-04-18 19:33:33 UTC 
It doesn't seem that dhclient DAD's working in dhclient-3.0.5-31.el5, thus I'm unable to reproduce if the dhclient behaves correctly.


Here's what I tried on RHEL5.9-Server-20120417.1.n, dhclient-.0.5-31.el5.x86_64:

# ip a s dev eth0
2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast qlen 1000
    link/ether 52:54:00:63:02:ab brd ff:ff:ff:ff:ff:ff

# dhclient -1 -pf /var/run/dhclient.pid -lf /var/lib/dhclient/dhclient.leases eth0

Internet Systems Consortium DHCP Client V3.0.5-RedHat
Copyright 2004-2006 Internet Systems Consortium.
All rights reserved.
For info, please visit http://www.isc.org/sw/dhcp/

Listening on LPF/eth0/52:54:00:63:02:ab
Sending on   LPF/eth0/52:54:00:63:02:ab
Sending on   Socket/fallback
DHCPDISCOVER on eth0 to 255.255.255.255 port 67 interval 5 (xid=0x68886723)
DHCPOFFER from 192.168.1.40
DHCPREQUEST on eth0 to 255.255.255.255 port 67 (xid=0x68886723)
DHCPACK from 192.168.1.40 (xid=0x68886723)
bound to 192.168.1.1 -- renewal in 299 seconds.

And output from tcpdump running on the client that ran the dhclient:

# tcpdump -s0 -vvvni eth0 udp port 67 or udp port 68 or arp
tcpdump: WARNING: eth0: no IPv4 address assigned
tcpdump: listening on eth0, link-type EN10MB (Ethernet), capture size 65535 bytes
15:27:42.321853 IP (tos 0x10, ttl  16, id 0, offset 0, flags [none], proto: UDP (17), length: 328) 0.0.0.0.bootpc > 255.255.255.255.bootps: [udp sum ok] BOOTP/DHCP, Request from 52:54:00:63:02:ab, length: 300, xid:0x23678868, flags: [none] (0x0000)
          Client Ethernet Address: 52:54:00:63:02:ab
          Vendor-rfc1048:
            DHCP:DISCOVER
            RQ:192.168.1.1
            PR:SM+BR+TZ+DG+DN+NS+HN+YD+YS+NTP+MTU
15:27:42.322348 IP (tos 0x10, ttl 128, id 0, offset 0, flags [none], proto: UDP (17), length: 328) 192.168.1.40.bootps > 192.168.1.1.bootpc: [udp sum ok] BOOTP/DHCP, Reply, length: 300, xid:0x23678868, flags: [none] (0x0000)
          Your IP: 192.168.1.1
          Client Ethernet Address: 52:54:00:63:02:ab
          Vendor-rfc1048:
            DHCP:OFFER
            SID:192.168.1.40
            LT:600
            SM:255.255.255.0
            DN:"example.org"
            NS:10.34.255.7,10.34.255.6
15:27:42.323497 IP (tos 0x10, ttl  16, id 0, offset 0, flags [none], proto: UDP (17), length: 328) 0.0.0.0.bootpc > 255.255.255.255.bootps: [udp sum ok] BOOTP/DHCP, Request from 52:54:00:63:02:ab, length: 300, xid:0x23678868, flags: [none] (0x0000)
          Client Ethernet Address: 52:54:00:63:02:ab
          Vendor-rfc1048:
            DHCP:REQUEST
            SID:192.168.1.40
            RQ:192.168.1.1
            PR:SM+BR+TZ+DG+DN+NS+HN+YD+YS+NTP+MTU
15:27:42.324905 IP (tos 0x10, ttl 128, id 0, offset 0, flags [none], proto: UDP (17), length: 328) 192.168.1.40.bootps > 192.168.1.1.bootpc: [udp sum ok] BOOTP/DHCP, Reply, length: 300, xid:0x23678868, flags: [none] (0x0000)
          Your IP: 192.168.1.1
          Client Ethernet Address: 52:54:00:63:02:ab
          Vendor-rfc1048:
            DHCP:ACK
            SID:192.168.1.40
            LT:600
            SM:255.255.255.0
            DN:"example.org"
            NS:10.34.255.7,10.34.255.6

Aside from this, notice different xid in UDP packets and xid reported by dhclient itself.
Comment 6 Ladislav Jozsa 2012-04-19 16:57:29 UTC 
Please scratch the comment #5. The issue was originally reported for version 3.x of dhclient which is part of RHEL5 and I thought that 3.x is what needs to be tested.

I have re-verified it on RHEL6.3-20120411.1, dhclient-4.1.1-30.P1.el6. Actual behaviour is correct, dhclient detects that IP address is in use and sends DHCPDECLINE and exits with code 2.
Comment 10 errata-xmlrpc 2012-06-20 12:43:46 UTC 
Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.

For information on the advisory, and where to find the updated
files, follow the link below.

If the solution does not work for you, open a new bug report.

http://rhn.redhat.com/errata/RHBA-2012-0793.html