See entire packet payload using tcpdump

I just needed to help our dev team in proving that certain IM messages weren't being queued and then delivered once connection resumes. That calls for a TCPDUMP!  This command will show you the entire payload of a packet. The final "s" increases the snaplength, grabbing the whole packet. tcpdump -nnvvXSs 1514 -i <device> <filters> eg tcpdump -nnvvXSs…

Quick subnetting reference

 CIDR block           Subnet Mask                 IP Quantity   /32                         255.255.255.255            1   /31                         255.255.255.254            2   /30                         255.255.255.252            4   /29                         255.255.255.248      …

MS DTC

We recently released a custom app which requires the use of MS DTC. It's a lengthy process to implement it and it took me a looong time to get it working (the first time).Hope this helps:Enable a firewall exception for MS DTC using Windows Firewall Open Windows Firewall.To open Windows Firewall, on the Start menu, click Control…

Permanent MTU settings for PPP0 Ubuntu

We were having issues with slow TX/RX between two sites over a PPTP VPN connection. I found that the issue was MTU mismatches and used this command to fix it:sudo ifconfig ppp0 mtu 1492Just need to mention that this did not really do much to fix the speed issue and in the end we decided…

How to add permanent static routes in Ubuntu

We first tried to use pptp as our site-to-site VPN protocol and it required some static routes to allow LAN traffic (eth0 for example) to be routed to another site (ppp0 for example). These commands can help to add a static route on a Linux server:NOTE:Advantages of Static RoutesEasy to configureNo routing protocol overheadDisadvantages of…

IPTables: Not for the fainthearted

All our sites run a mixture of defense tools, but IPTables form part of the frontlines! (stop inferring! 😉 )Here are some handy examples for IPTables:1. Delete Existing RulesBefore you start building new set of rules, you might want to clean-up all the default rules, and existing rules. Use the iptables flush command as shown…