Newsletter |
![]() |
Tools & Tricks
Here we provide short tips and reminders to things that will save time.
Blocking traffic
How to block traffic.Linux - Stuff
Bash CommandsCLUI commands we hardly ever use
at 8:00
at> reboot
at> (CTRL+d to exit)
# /usr/sbin/sendmail -bt
ADDRESS TEST MODE (ruleset 3 NOT automatically invoked)
Enter [ruleset] [address]
> 3,0 tester@testdomain.com
> (CTRL+d to exit)
Issue tcpdump -i eth0 -n 'port ! 22' when you need to use TCPdump on an SSH connection
Issue ln -s [source] [target] when you need to make a soft link. This is similar to the windows "shortcut" concept.
Here is a summary of the meanings for individual octal digit values:
0 --- no permission 1 --x execute 2 -w- write 3 -wx write and execute 4 r-- read 5 r-x read and execute 6 rw- read and write 7 rwx read, write and execute
Cisco - Stuff
Character Description ! Each exclamation point indicates receipt of a reply. . Each period indicates the network server timed out while waiting for a reply. U A destination unreachable error PDU was received. Q Source quench (destination too busy). M Could not fragment. ? Unknown packet type. & Packet lifetime exceeded.
Character Description ! success * time out N network unreachable H host unreachable P protocol unreachable A admin denied Q source quench received (congestion) ? unknown (any other ICMP message)
ip flow-cache entries 4000 ip flow-cache timeout inactive 100 ip flow-top-talkers top 10 sort-by bytesThen on the interface that is showing the heavy load add the commands depending on the traffic direction ip flow ingress or ip flow egress
To see the results issue the command sh ip flow top-talkers
Things to watch for when creating L2L VPN connections
eSubnet Services
Contact us regarding your network,
security and Internet services needs
Contact us regarding your network,
security and Internet services needs
ESUBNET ENTERPRISES INC. TORONTO CANADA