Linux Administrator's blog

Configuring NSEL (Netflow Secure Event Logging) with Cisco ASA and Centos 6 server

Posted on:: March 8, 2013
Author:: shamot

These are the steps we need to do to make everything work together: Enable NetFlow feature on ASA box Install nfdump and nfsen software to collect the data from ASA Install and configure web server (eg. Apache) to make the graphs accessible via web browser 1. ASA setup ASA 5000 series comes with NetFlow version […]

Posted in ASA 5000 series, Cisco devices configuration, network administration software, Network Topology | No Comments

AOL’s misconfigured SMTP servers bouncing emails with 521 error

Posted on:: January 31, 2013
Author:: shamot

We’ve fount out there is a problem with AOL SMTP servers that randomly reject emails with this hard error code: 521 5.2.1 “Service unavailable. Please try again later.” In fact this doesn’t happen very often and we may not have noticed something like that even happens if we hadn’t sent newsletters to our customers which […]

Posted in Server administration | 16 Comments

Fixing the problem with accessing the VCenter from web after vSphere 5.0 installation

Posted on:: January 9, 2013
Author:: shamot

Maybe you wonder (just like I did) why it’s not possible to manage vCenter from web browser after installing vSphere Web Client which should make this possible. After vSphere Web Client successful installation, I opened up a main vCenter web page running on https://vcenter_ip and clicked on “Log in to vSphere Web Client” which gave […]

Posted in Virtualization | 8 Comments

Centos/RHEL 6 and authentication against LDAP with SSS approach

Posted on:: December 7, 2012
Author:: shamot

There was a new approach of how to setup a LDAP authentication presented with RHEL 6. This new method called SSS is a replacement of pam_ldap. SSS states to be more flexible and also includes own caching mechanism which also means that NSCD daemon can’t be setup to cache the users/passwords once you run it […]

Posted in Server administration | No Comments

Configuring OpenVPN authentication against LDAP (configured on Centos 5.8)

Posted on:: October 2, 2012
Author:: shamot

There is a possibility to configure OpenVPN server to authenticate users with additional login/password prompt. This can be used as an only user verification method or in additional to either standard pre-shared keys or certificates exchange configurations. We were using certificate authentication method in our company for a long time waiting to have LDAP configured […]

Posted in Server administration | 1 Comment

Cisco ASA 55xx and ESMTP inspection breaks TLS

Posted on:: October 31, 2011
Author:: shamot

It’s been few days when we discovered a problem with sending emails using TLS in our company. We found out the problem with sending emails via TLS was the result given by the email server after “STARTTLS” command: > 502 5.5.2 Error: command not recognized First it seemed as the destined server didn’t implement TLS […]

Posted in ASA 5000 series, Cisco devices configuration | No Comments

Policy-based routing with Catalyst 3560

Posted on:: September 29, 2011
Author:: shamot

Wanted to setup PBR routing on our two Cisco catalyst 3650 boxes I was searching for some more information how to achieve that. I found this page describing how to setup PBR in few steps. After reading some about PBR functionality from official Cisco documents I was playing a bit with it but I couldn’t […]

Posted in Catalyst 3560, Cisco devices configuration | No Comments

Automatic server installation via PXE (examples from Centos) – Part 1

Posted on:: January 16, 2011
Author:: shamot

PXE kickstart

Posted in Server administration | No Comments

PS3 jailbreaking using Linux and Nokia N800

Posted on:: September 12, 2010
Author:: shamot

As I am one of lucky owners of PS3 and because of source code of Psgroove being published on internet in recent weeks a also started to investigate how to jailbreak my PS3 myself. Finally I decided to share my experience here. First of all you have to stay on firmware version 3.41 otherwise you […]

Posted in Programming, PS3 | 3 Comments

IP segments, DNS zones and hostname best practice

Posted on:: July 24, 2008
Author:: shamot

Once I needed to come up with some reasonable convention of network and DNS zoning as the company network should have consist of few offices connected together with few more server housing centres. IP segments, DNS zoning and hostname conventions must have been taken into account. I was given a free hand as any sofisticated […]

Posted in network concepts, Network Topology | 1 Comment