Cisco FTD – permit bpdu frames

In the old days of Cisco ASA transparent firewalls, there was an option to allow BPDU frames in access list. Therefore, bpdu frames were passing through the firewall even some rule later could overide it. ASA ACL looked something like this. access-list acl-bpdu ethertype permit bpduaccess-group acl-bpdu in interface inside In the FTD there is no way to allow this using Access control policies. By default BPDUs are forwarded for

Ping tricks

Change Ping Packet Size Win:     ping –l 1450 IP_ADDRESS Linux:  ping –s 1450 IP_ADDRESS Send 10 packets and stop Win:  ping –n 10 IP_ADDRESS Linux: ping –c 10 IP_ADDRESS Show ping statistics without stopping Linux ping :  Press Ctrl + |  (pipe) hostname:~ $ ping 10.6.10.70 PING 10.6.10.70 (10.6.10.70) 56(84) bytes of data. 64 bytes from 10.6.10.70: icmp_seq=0 ttl=117 time=193 ms 64 bytes from 10.6.10.70: icmp_seq=2 ttl=117 time=192 ms 3/3

Cisco SSH access hardening

It is 2019 and plenty of network devices still rely on old crypto algorithms and functions. Therefore, I decided to write down some best practices for hardening SSH on Cisco routers / switches. I tested these setting on IOS-XE 16.x releases.  This article is meant as a write-down of picked security practices. You can find more technical deep-dive meaning of the commands by internet research. In fact, when it comes

Snmpwalk tricks

snmpwalk xyz.network.local snmpwalk -v1 -c community xyz.network.local … snmpget -v 2c –c community xyz.network.local … rnetstat –ix xyz.network.local Interface description   Status of Interfaces   System uptime   Interface IP addresses   Last change of interfaces   TCP connection state – who is connected on which port   Other options ifAdminStatus ifOperStatus ifPhysAddress  (mac address) ifSpeed ifType sysContact.0 sysName.0 sysLocation.0

Cisco vs. HP ProCurve VLAN switch ports

Usually, when Cisco oriented networker sets off to the HP networking world, first confusing thing is VLAN port assignment. When speaking about VLAN ports in HP world, the ports can be tagged or untagged (despite the access / trunk ports in Cisco). As you may guess, tagging means 802.1q tagging in Ethernet frames. It is important to realize that Cisco is “port-centric”, whereas Procurve is is “vlan-centric” when speaking about