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Change Linux Primary IP Address Without Losing Connectivity

You need to change an IP address of an interface on a Linux server without loosing connectivity, so here’s one way: First add a secondary IP address to the interface: ip addr add dev eth0 ip addr show eth0 And confirm: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP link/ether 44:38:39:00:11:aa brd ff:ff:ff:ff:ff:ff inet scope global eth0 inet… 

MySQL Buffered warning: Changed limits: max_connections: 214 (requested 800)

This is always an interesting one, comes up from time to time especially if you run a server with heavy database traffic. Possibly you’ve modified you my.cnf with various tweaked settings for ‘max_connections’ or ‘open_files_limit’ but your your ‘mysqld.log’ you start getting: [Warning] Buffered warning: Changed limits: max_open_files: 1024 (requested 5000) [Warning] Buffered warning: Changed limits: max_connections: 214 (requested 800)… 

Ubiquiti ER-X EdgeRouter Increase Performance Tweak

If your like most home/office network tweakers looking for every bit of performance you can squeeze out of your home network. For $49 the small, yet powerful Ubiquiti ER-X is a great value offering gigabit ports, PoE, small form factor and VPN functionality.

As with any router the manufacturers release software updates periodically that offer fixes, security patches and added features. In once example, enabling hardware offloading on the Ubiquiti ER-X models.

Offloading is used to execute functions of the router using the hardware directly, rather than a process of software functions to greatly increase performance. The benefit of enabling offload in EdgeOS is increased performance and throughput by not limiting the performance to the CPU.

Cisco ASA 5508-X FirePower Threat Defense Appliance Reimage

Recently I was given a Cisco ASA 5508-X Firepower Threat Defense appliance to deploy. While these are the same hardware platform as the tried-true Cisco ASA 5508 firewalls, these run Cisco’s new ‘unified’ SourceFire linux based operating system (asa-ftd), which is essentially an operating system combining the SourceFire FirePower functionality with Cisco’s conventional firewalling capabilities. It’s Cisco’s new direction for combining these two platforms in to one hardware solution.

Without getting in to uber nerd verbosity, after unboxing the new unit and attempting to patch the OS to a new upgrade (version 6.0.2 -> 6.2.2), I was presented with a failed upgrade due to a corrupt MySQL database. Seriously ? This is why I loved the regular Cisco ASA in the first place, minimal OS running from flash memory, upgrades typically only require putting the new firmware in place, telling the Cisco ASA to boot the new firmware and reboot. The new SourceFire OS – it’s a full blown linux OS using MySQL for its backend, sigh… Since it was a new deployment and I couldn’t repair the tables or database I figured I’d go ahead and reach out to the Cisco TAC for insight.

Windows 10 SSH Aliases

Windows 10 build 1803 April 2018 update now includes by default openSSH for Windows – no more WSL, emulation or other work arounds – a full blown fully integrated SSH client in Windows. The executables are stored in C:\Windows\System32\OpenSSH and also include scp.exe and sftp.exe. A great way of making this even more functional for daily use is creating what… 

Cisco ASA Utility PING TCP

Problem On a Cisco ASA you can specify which interface to launch a ‘ping’ from, but that’s it. However sometimes in troubleshooting you may find yourself with access to all remote assets to triangulate issues full or to properly initiate ‘interesting traffic. We can use TCP PING in an interactive manner with a variety of parameters. Note: You need ASA…