Friday, May 9, 2008, 05:03 PM - Networking
I'm big on security, but not at the expense of usability and privacy. When it comes to VPN connections, I prefer split tunneling. Split tunneling means instead of forcing all traffic through the VPN, only traffic destined for the remote subnet goes through the VPN.
Here are my arguments:
1. Forcing all traffic through the VPN doesn't provide a lot more security because:
a. Traffic is encrypted from the user to the other end of the VPN, but not from there to the final destination.
b. Traffic destined for external networks probably do not need to be secured anyways.
c. The VPN client can usually be turned on and off at any time.
d. When "local lan" is enabled, the computer connected to the vpn is still susceptible to attack from the public non-secured network by tunneling through another computer on the LAN first.
2. Forcing all traffic through the VPN causes all of the following problems:
a. Traffic between a user and external computers can be slowed down considerably.
b. Traffic for others inside the secured network is slowed down by a VPN user needlessly.
c. Certain protocols may be broken.
d. Network applications get disconnected during VPN connection and must re-connect.
e. Privacy. Personal traffic like emailing your spouse should not be forced to travel through your work network.
Disabling split tunneling may be ok for road-warriors, but for employees who work from home and need to constantly access both work resources and the Internet, it can be very annoying.
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( 3 / 47 )Friday, March 7, 2008, 10:24 AM - Programming
The combination of these four conditions was causing VS.Net 2003 to give me that unexplicable linker error.
1. Class has virtual DTOR.
2. Class is inside another class.
3. Class is built into a static library.
4. PCH is on.
Removing any one of those conditions would solve the problem. I chose #2, by moving my class to namespace level.
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( 2.3 / 35 )Friday, July 27, 2007, 03:24 PM
This page helped me figure out how to debug a problem I was having trying to run a windows service: blogs.msdn.com
In short, you can create a service that will launch cmd.exe as the local system user, by running this:
sc.exe create testsvc binpath= "cmd /K start" type= own type= interact[ add comment ] | permalink |
( 2.7 / 50 )Saturday, June 23, 2007, 04:07 PM - Linux, Networking
My workplace has a Fortinet IPSEC VPN, which I connect to from my Linux server. There are multiple subnets at work, like 192.168.0.0/21 and 10.2.2.0/24, and this was causing problems.
Everything was working great, except I could only connect to computers on one subnet at a time. If I connected to a computer on the other subnet, the first subnet would stop working, and I would have to restart racoon to make it work again (actually I just had to reset my SAD entries, with setkey -F, and let it re-associate).
To make a long story short, the problem was that Fortinet cannot handle multiple tunnels like that. If you establish a second tunnel, it uses the keys negotiated in that tunnel from then on. It doesn't use the first tunnel. This post explains it a little better.
Well I never wanted two tunnels in the first place. I only want one tunnel even though there are multiple subnets on the remote side. To fix it, I simply had to use
require instead of unique on my SPD entries!
I'm using Debian's racoon-tool to create my spd entries (and racoon.conf). With racoon-tool, you simply have to add the
level: require option to each of your connections in your racoon-tool.conf.
BTW, my tunnel looks like this:
a.b.c.d/32 => a.b.c.d => x.y.z.w => 192.168.0.0/21
not like this:
192.168.8.0/24 => a.b.c.d => x.y.z.w => 192.168.0.0/21
Since my Linux server performs NAT (MASQUERADE) in iptables, I only need the tunnel to go to my server, not to my whole LAN subnet. Somehow it is smart enough to do NAT and then encrypted on the way out, and decrypt then un-NAT on the way in, or something like that. BTW, it's so smart that even when I was having problems with two tunnels from my server, the computers inside my LAN could connect to both remote subnets with no problem! I believe this is due to a special MASQ table that can dynamically associate SPI values. This page explained it well for me.
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( 2.8 / 59 )Tuesday, May 15, 2007, 08:11 AM - Personal, Networking
Spammers got me again, even with captchas in place.
I don't have time to sit around and delete spam posts all day, so I'm going to have to disable comments, sorry.
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