Archive for the 'Networking' Category

 

 

May 29 2017

Determine OS within FTP Session

Published by under Networking

The “QUOTE” FTP keyword is essential to allow a user to run system-specific commands on servers (eg SITE or ALLO)   Most FTP clients send a NOOP – that actually is a dummy packet – to keep the connection up ftp> quote noop 200 NOOP ok.   QUOTE SYST returns the Operating System the FTP […]

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May 06 2015

Deny VLAN Access to a Mac Address on Cisco Catalyst

Published by under Cisco,Security

Mac addresses can be filtered out with port security, mac access lists or even 802.1x port-based authentication with Radius. Mac access ACL requires a higher end switch while 802.1x authentication is a pretty heavy setup and needs to manage a mac address database on a Radius server. Port security allows you to permit some mac […]

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Oct 24 2013

Run DHCP Relay on a Cisco Catalyst 2960

Published by under Cisco

Having a DHCP relay on a layer 2 switch is usually a nonsense. I happened to get a crash on a DHCP server and had no hands on the ISP router at a remote site. This was my only option to avoid a massive change for static IP. Some say layer 2 devices cannot deal […]

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