Problems with using grab 1.0.2 and ftp.mirror.ac.uk and ftp.ximian.com

Hello list,

I installed grab recently on a RH7.2 machine. This machine is running
from behind a LINUX masquerading firewall with the ftp masquerading
module running. When using the normal ftp program I can download files
from ftp.mirror.ac.uk without any problem. (Also from opera this is not
a problem, only the progress indicator doesn't work).
Now I try to use grab 1.0.2 (the rpm downloaded from the download
directory). I configure the server in such a way that grab would find
the RH7.2 installation and the updates for RH7.2 on the mirror at
ftp.mirror.ac.uk. (lbl.gov is too slow here for me).

When doing an update I get the following:

---------------------
[root@pc300 root]# ./grab-devel --update
-Updating remote RPM cache database
 ->Grabbed and indexed [1] RPMS from [email protected]
 ->Grabbed and indexed [6] RPMS from [email protected]
 ->Grabbed and indexed [1232] RPMS from [email protected]
 ->Grabbed and indexed [284] RPMS from [email protected]
 ->Grabbed and indexed [2] RPMS from [email protected]
 ->Grabbed and indexed [218] RPMS from [email protected]
-Updating remote provides database with new packages
  (you can disable this in /etc/grab/defaults or --nodeps)
 -> 0% Canna-devel-3.5b2-50.i386.rpmerror: open of ftp://Canna-devel-3.5b2-50.i386.rpm failed: Operation not permitted
warning: u 0x820e998 ctrl 0x82163a0 nrefs != 0 (Canna-devel-3.5b2-50.i386.rpm ftp)
----------------------


and then the same error for every package he wants to access for the
dependency information. Originally I used the LBL.GOV site for RH7.2 and
that seemed to work so the ftp seems to be incompatible with
ftp.mirror.ac.uk.

When trying to install a package without there is also a problem with
downloading the packages as is seen in the next session:

---------------------
[root@pc300 root]# ./grab-devel --showall --status U --search ximian
-Comparing 218 of 1729 with Valgor
-Obtaining current RPM list
-Filtered Package Statistics:
 0 Consolidated, 0 Diff Arch, 0 Current, 0 Skip List, 197 Other Status
-Please select one (or more) of the following matched RPMS:

 Num S Package name       Version     Installed   Arch   Size   Server Desc
 --- - ------------------ ----------- ----------- ------ ------ ---------------
 1   U ORBit              0.5.15-1.xi 0.5.8-4     i386   626K   XIMGNOME@XIMIAN.
 2   ...

-Choose number(s): ('?' for help): 1
-Here is what I will download:

 Num Package To Download                         Location
 --- ------------------------------------------  -----------------------------
 1   ORBit-0.5.15-1.ximian.1.i386.rpm

-You selected 626K of archives
 ->Do you want to continue? [Y/n]: 
-Building local package provides database
-Searching for unresolved dependencies
 checking (100%): ORBit-0.5.15-1.ximian.1.i386.rpmerror: open of ftp:////ORBit-0.5.15-1.ximian.1.i386.rpm failed: Operation not permitted
warning: u 0x820e948 ctrl 0x8216338 nrefs != 0 (/ ftp)
-Grabbing the selected packages...                                            
 (1/1) ORBit-0.5.15-1.ximian.1.i386.rpm               100%  626/626 kB - 0 kB/s
-FATAL: Could not connect to !
-All downloaded RPMS passed validation
------------------------

Things I already tried to solve this problem:
- update the perl-libnet package to the latest version 1.0901.
- Tried with and without passive download of files.
- downloaded the latest development version of the grab script
but to no avail.

Any reactions or help ?

greets,
Staf.