Just got an confirmation from QA, they're able to kickstart RHEL5 over RHN Proxy on RHEL6 without any issues. This does not look to be a RHN Proxy bug.

Make sure, the kernel-2.6.18-398.el5.x86_64.rpm has the right size/checksum.

Taking...

Hello, 
Yes, I can reproduce the bug and after some investigation I have:

1) There are, actually, 2 bugs:
- On the side of Proxy (squid)
- On the side of Anaconda (for RHEL 5).


2) Why it happens for RHEL 5 and doesn't for RHEL 6?
Installation of packages by Anaconda can be divided on 3 steps:

----1--- 
Downloading of metadata for a repository: repodata/repomd.xml, primary.xml.gz, comps-rhel5-vt.xml, filelists.xml.gz

----2--- 
Extract from metadata (primary.xml) information about range of RPM-header for every package, something like this:
<rpm:header-range start="440" end="19045"/>

and download RPM-header with range GET request, e.g.:

GET /ty/5cuO9OQ6/Server/kernel-2.6.18-398.el5.x86_64.rpm HTTP/1.1^M
Accept-Encoding: identity^M
Range: bytes=440-996355^M
Connection: close^M
Host: dhcp131-19.brq.redhat.com^M
User-agent: urlgrabber/3.1.0 yum/3.2.22^M


In /var/log/squid/access.log:
363:1457694721.703    417 127.0.0.1 TCP_MISS/206 996393 GET http://dhcp131-19.brq.redhat.com/ty-cksm/fc669e3a67c667843a2105e66a8c7ab7/Server/kernel-2.6.18-398.el5.x86_64.rpm - DIRECT/10.34.131.19 application/octet-stream

TCP_MISS/206 looks OK, we have no the package in the cache and this is Range-request (code 206).

----3-----

Download all packages to install them.

In config of squid we have parameter:
range_offset_limit -1 KB
It means that squid download whole file, even range request.

Actually during downloading packages Squid do not return the whole package to Anaconda after range request.
It is possible to reproduce the bug with curl
curl -v --get \
     -H 'Host: dhcp131-19.brq.redhat.com' \
     -H 'Connection: close' \
     -H 'Accept-Encoding: identity' \
     -H 'Range: bytes=440-996355' \
     -A 'urlgrabber/3.1.0 yum/3.2.22' \
     'http://dhcp131-19.brq.redhat.com/ty/5cuO9OQ6/Server/kernel-2.6.18-398.el5.x86_64.rpm' -o kernel-2.6.18-398.el5.x86_64.rpm-head

curl -v --get \
     -H 'Host: dhcp131-19.brq.redhat.com' \
     -H 'Connection: close' \
     -H 'Accept-Encoding: identity' \
     -A 'urlgrabber/3.1.0 yum/3.2.22' \
     'http://dhcp131-19.brq.redhat.com/ty/5cuO9OQ6/Server/kernel-2.6.18-398.el5.x86_64.rpm' -o kernel-2.6.18-398.el5.x86_64.rpm

You will see an error 
curl: (18) transfer closed with 20755079 bytes remaining to read

The same error in anaconda.log, but on RHEL 6 Anaconda tries to download package again, e.g.:

15:26:33,326 WARNING : Try 1/10 for http://dhcp131-19.brq.redhat.com/ty/6BGjRC8Z/Packages/kernel-firmware-2.6.32-573.el6.noarch.rpm failed: [Errno 14] PYCURL ERROR 18 - "transfer closed with 9163780 bytes remaining to read"
15:26:33,579 WARNING : Failed to get http://dhcp131-19.brq.redhat.com/ty/6BGjRC8Z/Packages/kernel-firmware-2.6.32-573.el6.noarch.rpm from mirror 1/1, or downloaded file is corrupt
15:26:33,581 WARNING : package download failure, retrying automatically

As a workaround you can do:
- Downgrade squid to version squid-3.1.10-29.el6.x86_64
yum downgrade squid-3.1.10-29.el6.x86_64

OR

- change squid config

remove: range_offset_limit -1 KB
add: request_header_access Range deny all

Anaconda Bug 1317864

Squid Bug 1319705

The blocking squid issue has been fixed in RHEL 6.8 (Bug 1319705) and the plan is to backport the fix to RHEL 6.7.z (Bug 1322709).

Based on that I'm switching this BZ to ON_QA.

Tested with squid-3.1.23-16.el6 containing the fix for BZ 1319705. Performed reprovisioning of RHEL 5 client via RHN Proxy on RHEL 6 server 30 times, never failed, always went through without any problem.

VERIFIED