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

How to Deny / Force VLAN Access to a Mac Address on Cisco

Published by under Cisco,Security

Different methods exists to filter out mac addresses on a switch such as:– port security,– mac access lists or even– 802.1x port-based authentication with Radius. Mac access ACL require 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 […]

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Oct 24 2013

Run a DHCP Relay on a Cisco Catalyst 2960 Switch

Published by under Cisco

Having a DHCP relay on a layer 2 switch is usually a nonsense. A DHCP server happened to crash and I had no access to configure a new DHCP service on the ISP router at a remote site.My only option was to set a DHCP relay on the switch that will forward requests to another […]

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May 11 2013

Freeradius Usage Graphs

Published by under Freeradius

Radius servers generate a lot of accounting records. Is it worth keeping them? Damn yeah! Beside the fact they could be used to check if a customer was connected at a given date, or find out who got IP address X.X.X.X that same day, the most interesting is to generate traffic reports and show customers […]

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Feb 05 2013

No SNMP Response from Fortigate 100D

Published by under Fortinet

Even though SNMP is enabled on the internal interface, I get a timeout running cfgmaker (to configure MRTG) or snmpwalk. I did not get this issue on a Fortiwifi 60B.   The trick is you have to configure the management interface and query that interface if you want to get SNMP information for all other […]

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