Teun Docter
2015-Sep-11 21:24 UTC
[syslinux] pxelinux tries to load ldlinux.c32 from DHCP server, instead of next-server
Hello list,
We have a scenario where our TFTP server is not the same IP as our DHCP
server. While testing with 6.03, our setup works just fine.
However with the master branch, for some reason pxelinux.0 is fetched
from the TFTP servers IP, but then it tries to load ldlinux.c32 from the
DHCP servers IP.
I've tracked down this problem to the following commit:
8e53b8a63c8ae1e266f63f502a537b9e8e03baed core/pxe: Don't prevent
serverip override
If I reverse that change on the current master everything is working
fine. This was with tested against 26d37f75aff50879795692728dbeb8ca57a8a226.
We're not using uefi for this test. (The machine is actually a KVM
instance in OpenStack.)
I've captured the following DHCP ACK:
10.141.20.1.bootps > 10.141.20.2.bootpc: [udp sum ok] BOOTP/DHCP, Reply,
length 399, xid 0xf0eb955a, secs 14, Flags [none] (0x0000)
Your-IP 10.141.20.2
Server-IP 10.141.255.254
Client-Ethernet-Address fa:16:3e:08:31:b9
Vendor-rfc1048 Extensions
Magic Cookie 0x63825363
DHCP-Message Option 53, length 1: ACK
Server-ID Option 54, length 4: 10.141.20.1
Lease-Time Option 51, length 4: 86400
RN Option 58, length 4: 43200
RB Option 59, length 4: 75600
TFTP Option 66, length 7: "master^@"
BF Option 67, length 11: "pxelinux.0^@"
Subnet-Mask Option 1, length 4: 255.255.0.0
BR Option 28, length 4: 10.141.255.255
Domain-Name-Server Option 6, length 4: 10.141.20.1
Domain-Name Option 15, length 14: "openstacklocal"
Hostname Option 12, length 16: "host-10-141-20-2"
Default-Gateway Option 3, length 4: 10.141.255.250
T209 Option 209, length 45:
112.120.101.108.105.110.117.120.46.99.102.103.47.99.97.116.101.103.111.114.121.46.118.105.114.116.117.97.108.45.110.111.100.101.115.46.111.112.101.110.115.116.
97.99.107
MTU Option 26, length 2: 1450
END Option 255, length 0
Followed by this TFTP request:
10.141.20.2.49152 > 10.141.20.1.tftp: [udp sum ok] 41 RRQ
"ldlinux.c32"
octet tsize 0 blksize 1408
It should be sending that TFTP request to 10.141.255.254.
So now I'm wondering, could this be a bug? Or should we change something
in our DHCP settings? Is any further info required?
As a side note, could this be related to the recent thread with the
following subject: "BUG: confusion between next-server and gateway"?
(http://www.syslinux.org/archives/2015-September/024090.html)
Best regards,
Teun
Gene Cumm
2015-Sep-12 02:58 UTC
[syslinux] pxelinux tries to load ldlinux.c32 from DHCP server, instead of next-server
On Fri, Sep 11, 2015 at 5:24 PM, Teun Docter via Syslinux <syslinux at zytor.com> wrote:> Hello list, > > We have a scenario where our TFTP server is not the same IP as our DHCP > server. While testing with 6.03, our setup works just fine. > > However with the master branch, for some reason pxelinux.0 is fetched from > the TFTP servers IP, but then it tries to load ldlinux.c32 from the DHCP > servers IP.That seems like a regressive interaction.> I've tracked down this problem to the following commit: > > 8e53b8a63c8ae1e266f63f502a537b9e8e03baed core/pxe: Don't prevent serverip > override > > If I reverse that change on the current master everything is working fine. > This was with tested against 26d37f75aff50879795692728dbeb8ca57a8a226. > > We're not using uefi for this test. (The machine is actually a KVM instance > in OpenStack.)Always good to note. Thanks.> I've captured the following DHCP ACK: > > 10.141.20.1.bootps > 10.141.20.2.bootpc: [udp sum ok] BOOTP/DHCP, Reply, > length 399, xid 0xf0eb955a, secs 14, Flags [none] (0x0000) > Your-IP 10.141.20.2 > Server-IP 10.141.255.254 > Client-Ethernet-Address fa:16:3e:08:31:b9 > Vendor-rfc1048 Extensions > Magic Cookie 0x63825363 > DHCP-Message Option 53, length 1: ACK > Server-ID Option 54, length 4: 10.141.20.1 > Lease-Time Option 51, length 4: 86400 > RN Option 58, length 4: 43200 > RB Option 59, length 4: 75600 > TFTP Option 66, length 7: "master^@"What does the name "master.openstacklocal" point to? I typically set dhcp-66 to the dotted quad string of the destination TFTP.> BF Option 67, length 11: "pxelinux.0^@" > Subnet-Mask Option 1, length 4: 255.255.0.0 > BR Option 28, length 4: 10.141.255.255 > Domain-Name-Server Option 6, length 4: 10.141.20.1 > Domain-Name Option 15, length 14: "openstacklocal" > Hostname Option 12, length 16: "host-10-141-20-2" > Default-Gateway Option 3, length 4: 10.141.255.250 > T209 Option 209, length 45: > 112.120.101.108.105.110.117.120.46.99.102.103.47.99.97.116.101.103.111.114.121.46.118.105.114.116.117.97.108.45.110.111.100.101.115.46.111.112.101.110.115.116. > 97.99.107 > MTU Option 26, length 2: 1450 > END Option 255, length 0 > > Followed by this TFTP request: > > 10.141.20.2.49152 > 10.141.20.1.tftp: [udp sum ok] 41 RRQ "ldlinux.c32" > octet tsize 0 blksize 1408 > > It should be sending that TFTP request to 10.141.255.254.Depends on what master points at. Otherwise, it sounds like a broken interaction.> So now I'm wondering, could this be a bug? Or should we change something in > our DHCP settings? Is any further info required? > > As a side note, could this be related to the recent thread with the > following subject: "BUG: confusion between next-server and gateway"? > (http://www.syslinux.org/archives/2015-September/024090.html)-- -Gene
Teun Docter
2015-Sep-12 09:54 UTC
[syslinux] pxelinux tries to load ldlinux.c32 from DHCP server, instead of next-server
On 2015-09-12 04:58, Gene Cumm wrote:>> I've captured the following DHCP ACK: >> >> 10.141.20.1.bootps > 10.141.20.2.bootpc: [udp sum ok] BOOTP/DHCP, Reply, >> length 399, xid 0xf0eb955a, secs 14, Flags [none] (0x0000) >> Your-IP 10.141.20.2 >> Server-IP 10.141.255.254 >> Client-Ethernet-Address fa:16:3e:08:31:b9 >> Vendor-rfc1048 Extensions >> Magic Cookie 0x63825363 >> DHCP-Message Option 53, length 1: ACK >> Server-ID Option 54, length 4: 10.141.20.1 >> Lease-Time Option 51, length 4: 86400 >> RN Option 58, length 4: 43200 >> RB Option 59, length 4: 75600 >> TFTP Option 66, length 7: "master^@" > > What does the name "master.openstacklocal" point to? I typically set > dhcp-66 to the dotted quad string of the destination TFTP.Hmm, actually, it doesn't resolve.>> BF Option 67, length 11: "pxelinux.0^@" >> Subnet-Mask Option 1, length 4: 255.255.0.0 >> BR Option 28, length 4: 10.141.255.255 >> Domain-Name-Server Option 6, length 4: 10.141.20.1 >> Domain-Name Option 15, length 14: "openstacklocal" >> Hostname Option 12, length 16: "host-10-141-20-2" >> Default-Gateway Option 3, length 4: 10.141.255.250 >> T209 Option 209, length 45: >> 112.120.101.108.105.110.117.120.46.99.102.103.47.99.97.116.101.103.111.114.121.46.118.105.114.116.117.97.108.45.110.111.100.101.115.46.111.112.101.110.115.116. >> 97.99.107 >> MTU Option 26, length 2: 1450 >> END Option 255, length 0 >> >> Followed by this TFTP request: >> >> 10.141.20.2.49152 > 10.141.20.1.tftp: [udp sum ok] 41 RRQ "ldlinux.c32" >> octet tsize 0 blksize 1408 >> >> It should be sending that TFTP request to 10.141.255.254. > > Depends on what master points at. Otherwise, it sounds like a broken > interaction. >So, master does not resolve. But as per your suggestion, I've also tested with setting that field to the string "10.141.255.254". The behavior doesn't change though. Also, in my packet capture, with both settings, I don't see any DNS requests, which suggests to me it's not trying to use this field? My best guess would be that this is a bug that was introduced by the commit I mentioned earlier. What do you think? Thanks, Teun
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