Patches posted:
https://www.redhat.com/archives/libguestfs/2014-October/msg00243.html

A bit complex & risky for 7.1 however ...

Hi rjones,
i try to test this option "--password-file" with latest build:
libguestfs-1.28.1-1.8.el7.x86_64
virt-v2v-1.28.1-1.8.el7.x86_64

steps:
1. Prepare a file including esx server password:
# cat /tmp/passwd 
aaa---------------->>(for example)
# ll /tmp/passwd 
-rw-------. 1 root root 18 Nov  7 14:34 /tmp/passwd

2. Use virt-v2v convert a guest from esx server:

#  virt-v2v -ic vpx://root.111.25/tzheng-demo/10.66.106.63/?no_verify=1 test-rhel7.0-released-gui --password-file /tmp/passwd  -v -x 
virt-v2v: libguestfs 1.28.1 (x86_64)
[   0.0] Opening the source -i libvirt -ic vpx://root.111.25/tzheng-demo/10.66.106.63/?no_verify=1 test-rhel7.0-released-gui
input_libvirt_vcenter_https: source: scheme vpx server 10.66.111.25
libvirt: ESX Driver error : internal error: HTTP response code 500 for call to 'Login'. Fault: ServerFaultCode - Cannot complete login due to an incorrect user name or password.
virt-v2v: error: internal error: invalid argument: cannot open libvirt 
connection 'vpx://root.111.25/tzheng-demo/10.66.106.63/?no_verify=1'

If reporting bugs, run virt-v2v with debugging enabled and include the 
complete output:

  virt-v2v -v -x [...]

My result failed.

You know we have to input password twice, and i also tried with following way but failed.
# cat /tmp/passwd
aaa
aaa

so please help check whether the format for password file is right or not, thanks.

You need to make sure the password does not end with '\n'.

To prepare the password file do:

  echo -n password > /tmp/password

The password only needs to appear in the file once.

Hi rjones,
thanks for you reply, i tried again:
1.
# echo -n aaa >/tmp/passwd2
2.
#  virt-v2v -ic vpx://root.111.25/tzheng-demo/10.66.106.63/?no_verify=1 test-vmtools-bug1151610 -on test-vmtools-bug1151610-2 --password-file /tmp/passwd2
[   0.0] Opening the source -i libvirt -ic vpx://root.111.25/tzheng-demo/10.66.106.63/?no_verify=1 test-vmtools-bug1151610
[   1.0] Creating an overlay to protect the source from being modified
[   2.0] Opening the overlay
[  10.0] Initializing the target -o libvirt -os default
[  10.0] Inspecting the overlay
[  78.0] Checking for sufficient free disk space in the guest
[  78.0] Estimating space required on target for each disk
[  78.0] Converting Red Hat Enterprise Linux Server release 6.5 (Santiago) to run on KVM
virt-v2v: This guest has virtio drivers installed.
[ 462.0] Mapping filesystem data to avoid copying unused and blank areas
[ 462.0] Closing the overlay
[ 462.0] Copying disk 1/1 to /var/lib/libvirt/images/test-vmtools-bug1151610-2-sda (raw)
    (100.00/100%)
[ 617.0] Creating output metadata
Pool default refreshed

Domain test-vmtools-bug1151610-2 defined from /tmp/v2vlibvirt3290a0.xml

[ 618.0] Finishing off

Result: Conversion successfully and boot up with no error.
so move this bug from ON_QA to VERIFIED.

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.

https://rhn.redhat.com/errata/RHBA-2015-0303.html