mmcg's questions

I have a server mike at our office communicating with a remote server through a VPN. There have been various problems which seem to be linked to the MTU size. Mike is a RHEL 3 server and the customer server is CentOS 5. I used the tracepath tool to attempt to find the max MTU and got this weird result

[root@mike root]# tracepath 192.168.1.4
 1:  mike (192.168.100.1)                                  0.170ms pmtu 552
 1:  mike (192.168.100.1)                                  0.011ms pmtu 552
 1:  mike (192.168.100.1)                                  0.010ms pmtu 552

snip - thousands of lines of the same output

 1:  mike (192.168.100.1)                                  0.025ms pmtu 552
 1:  192.168.100.252 (192.168.100.252)                        0.405ms
 2:  192.168.100.253 (192.168.100.253)                        0.876ms
 3:  192.168.1.4 (192.168.1.4)                         97.1000ms reached
     Resume: pmtu 552 hops 3 back 3

From another server at our office to a different customer I get a far more reasonable looking result

[root@nora ~]# tracepath 192.168.2.1
 1:  nora (192.168.100.228)                                0.080ms pmtu 1500
 1:  192.168.100.253 (192.168.13.253)                      asymm  2   0.813ms
 2:  no reply
 3:  192.168.11.1 (192.168.11.1)                           73.210ms reached
     Resume: pmtu 1500 hops 3 back 3

So I think it is something to do with mike rather than the routers, firewalls or VPN inbetween. Any ideas?

In response to Daniel Lawson's answer below, here is why I believe that the problem is server mike as nora is able to get the right response

[root@nora ~]# tracepath 192.168.1.4
 1:  nora (192.168.100.228)                                0.101ms pmtu 1500
 1:  192.168.100.253 (192.168.100.253)                      asymm  2   0.863ms
 2:  no reply
 3:  192.168.1.4 (192.168.1.4)                        111.601ms reached
     Resume: pmtu 1500 hops 3 back 3

In response to Mike Pennington's comment both 192.168.100.252 and 192.168.100.253 are firewalls. The default gateway is 192.168.100.252 which then has a static route for these customers to send the traffic to 192.168.100.253. As they are on the same network I assume that is why the hop count isn't incremented.

I have a new server and a license for Exchange 2010 to install for a 50 user company with ~25GB of mail.

They previously used Exchange 2003 on 2 servers, 1 of which has been removed in the meantime. After Exchange 2003 they moved to MDaemon but now want to move to Exchange 2010 on the new server.

The old Exchange installation is unused but running on the 1 remaining server, do I need to upgrade/migrate this existing Exchange 2003 organisation?

Or

Can I delete Exchange 2003 and create a new 2010 installation from scratch? As Exchange and Active Directory are linked at the hip I don't know if this is possible.

Thanks, Mark

P.S. Is there any better way of transferring the data from Mdaemon than exporting from Outlook to a PST?

I’m working on a plan to replace a number of router/firewalls in our company’s and customer’s networks. We have 2 offices and a number of servers hosted in a datacentre that have IPSec VPN links to around 100 customer sites. In the main office we need a LAN and 2 DMZs and in the datacentre 3 LANs and a DMZ.

Most customer sites have either Gnatbox or Zywall firewalls but new sites could go out with a low end version of the same firewall that is in the main office/datacentre.

I had planned to use a Zywall USG 200 for the main office but this proved to be incapable in testing. When fully configured it takes over 30 mins to boot!

I have a shortlist of

Cisco ASA 5510
Watchguard XTM 520
Sonicwall NSA 3500
Juniper SRX240

Could anyone recommend any hardware or configurations?

I'm creating new virtual Linux servers on ESXi hosts. The existing systems are 32-bit RHEL with 4GB RAM. I am planning to create the new servers with 4GB RAM and run 32-bit CentOS 5.

If I want to add more RAM later I'd need to move to a PAE kernel. Is this possible / desirable ?

Thanks, Mark

Is the only changed needed to install a PAE kernel and boot from it? Does everything else stay the same?

On our company network there are a number of clients that are having problems connecting to the company file server (Windows Server 2003 R2 Enterprise x86). The share are mapped to a drive letter on the client. The drives are showing up with a red X and can't be opened.

Most people can access the network shares ok.

I have an idea that the workstation service is at fault. The output of net config workstation on a faulty computer is

C:\>net config workstation
Computer name                        \\vistacomputer
Full Computer name                   vistacomputer.xxxx.xxxx-xxxxxx.co.uk
User name                            username

Workstation active on 

Software version                     Windows Vista (TM) Business

Workstation domain                   xxxxxx
Workstation Domain DNS Name          xxxxxx.xxxx-xxxxxxxxx.co.uk
Logon domain                         xxxxxx

COM Open Timeout (sec)               0
COM Send Count (byte)                16
COM Send Timeout (msec)              250
The command completed successfully.

On a working computer it is

C:\>net config workstation
Computer name                        \\vistacomputerthatworks
Full Computer name                   vistacomputerthatworks.xxxx.xxxx-xxxxxx.co.uk
User name                            username

Workstation active on
     NetbiosSmb (000000000000)
     NetBT_Tcpip_{DABE06A7-5BF8-4ADF-B6C4-73EDB8D7971B} (00505694241B)

Software version                     Windows Vista (TM) Business

Workstation domain                   xxxxxx
Workstation Domain DNS Name          xxxxxx.xxxx-xxxxxxxxx.co.uk
Logon domain                         xxxxxx

COM Open Timeout (sec)               0
COM Send Count (byte)                16
COM Send Timeout (msec)              250
The command completed successfully.

Looks like the workstation service is disassociating itself from the network connections.

Any ideas?

I administer a number of linux servers that require telnet access for users. Currently the user's credentials are stored locally on each server and the passwords tend to be very weak and there is no requirement for them to be changed. The logons will soon be integrated with Active Directory and this is a more closely guarded identity.

Is it really a concern that user's password could be sniffed from the LAN given that we have a fully switched network so any hacker would need to insert themselves physically between the user's computer and the server?