How to Calculate MTU for Tunnels
WARNING: BORING ALERT!!!! If you have any tunnels in your network you may notice at times packet loss between subnets or perhaps stalled web sessions. This usually has to do with a combination of MTU negotiation and packet fragmentation. MTU 101 Maximum Transmission Unit refers to how much data in bytes the data layer can send forward. For ethernet the size is 1500 bytes, which coincides with how much data can fit in an ethernet frame. Within the MTU is another size called MSS (Maximum Segment Size) which refers to how much TCP data can be transmitted. This is also known as the payload and...
read moreCalculate Subnet Network Masks and CIDR notation
How to calculate the network mask from a CIDR notation, or a CIDR notation from a network mask. To figure this out we need to understand the relationship between the two. A network mask when written in binary will be 32 bits long. This also means that each octet of a network mask can hold a total of 8 bits. 255.255.0.0 == 11111111.11111111.00000000.00000000 255.255.255.0 == 11111111.11111111.11111111.00000000 255.255.255.192 == 11111111.11111111.11111111.11000000 Example 1-1: Calculate the network mask from CIDR Notation /16 1. First subtract the CIDR notation from the total number of bits...
read moreApache LDAP Authentication, Require ldap-group, OpenLDAP server, AND YOU!
OK peoples, this one frustrated me for a bit, but because I’m stubborn I figured it out. I have a webservice that I want to protect by using LDAP authentication within Apache from our OpenLDAP server. However, you want to make sure that the user belongs to a specific LDAP group. If you’re like me your groups look something like this: bart:~ jordan$ ldapsearch -h ldap.shop.lan -x -b "dc=shop,dc=lan" cn=fgstaff # extended LDIF # # LDAPv3 # base with scope subtree # filter: cn=fgstaff # requesting: ALL # # fgstaff, Groups, shop.lan dn: cn=fgstaff,ou=Groups,dc=shop,dc=lan cn:...
read moreHow To RAID Mac Mini Server without Reinstalling
Replicate boot drive to spare drive. While this post title specifically says Mac Mini Server, this procedure will work with any Macintosh that has more than one hard drive. Open Disk Utility One drive should be labelled “Server HD” and the other “Macintosh HD2″ Remember which one is on top and which one is on bottom. Select the Hard Drive associated with Macintosh HD2, and then click Restore Drag Server HD in to the source and Macintosh HD2 into the destination Make it go Build the spare drive into a RAID of one disk Open Disk Utility Select the Hard Drive...
read moreInstall vTiger from source on Ubuntu Server 10.04 LTS
I tried to install vTiger from the .bin file on their website. I tried CentOS, Ubuntu, and OpenSuSE. None could get through the installer without crashing. So I said forget it and installed from source. I spent over 3 hours with different distros trying to get the .bin file to work. It took me 15mins to figure it out from source. Here are step by step instructions on how to install vTiger 5.2.1 on a virgin Ubuntu Server 10.04 LTS Server: Download vTiger 5.2.1 source and extract tarball to /srv/www use apt-get to install the following packages: apt-get install mysql-server apache2-utils...
read moreSnow Leopard SSL Certificate Authority
As more services are introduced into your network and thus the more users you have, the need for security goes up. Maintaining your own certificate authority is a simple and free way to ensure the highest level of security while not breaking the bank. 1. Create the Certificate Authority First we’re going to hop into a terminal on any Mac OS X Server box and navigate to `/etc/certificates` and create some directories cd /etc/certificates/ sudo mkdir -p myCA/cert myCA/key cd myCA We need to create the CA signing certificate and key. After executing the first command you will be asked a...
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