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Change pptpd port on CentOS

I was testing Point-to-Point Tunneling today, between a CentOS 6 server running pptpd, and some Mikrotik routers as the clients, and I wanted to change the listening port on the pptpd side. After searching and reading a bit of documentation for a while, I was surprised to find that pptpd respects the record for pptp as defined in /etc/services.

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LPIC-2 Revision

My list of topics to revise, before taking the LPIC-2 exam. Note that this list was compiled before the exam objectives' revision in October 2013.


  • Example Servers: bigpie1, sds1, nicds1, officesrv
  • CentOS Install DHCP
  • dhcpd.conf


  • Example Servers: ldap-master, ldap-slave
  • Locate and examine LDIF files
  • ldapadd, slappasswd, ldappasswd, ldapdelete, getent, ldapsearch


  • /proc/sys/net/ipv4/ip_forward and sysctl.conf equivalent
  • RIP with routed


  • iptables chains, default policies
  • flush tables, add rules
  • configure NAT

SSH * Support programs: rpc.idmapd, rpc.mount.d, rpc.nfsd, rpc.statd, portmap * Setting up exports with NFS in /etc/exports, and on the fly with exportfs * showmount, nfsstat, rpcinfo * Mount over NFS

FTP * PAM Basics, PAM Stacks, Examples of PAM Modules * PAM Configuration, NSS Configuration

TCP Wrappers

  • /etc/hosts.allow, /etc/hosts.deny
  • Calling TCP Wrappers from /etc/inetd
  • /etc/xinetd


  • Network Design for SNORT


  • Fail2Ban configuration


  • Identifying active bootloader on a system (based on files on disk or with bootinfoscript)
  • LILO Error Messages
  • GRUB Legacy Error Messages
  • GRUB2 Error Messages and Rescue Console

Boot Time Troubleshooting

  • initrd
  • dmesg
  • /etc/inittab, runlevel, SysV and Upstart

Hardware Troubleshooting

  • Hardware detection (/proc/cpuinfo, lspci, lsusb, lsdev, lsmod)

Log files Troubleshooting

  • Helpful files: syslog, messages, dmesg or boot.log, secure, cron, lastlog
  • Scanning Log Files with head, tail, less, grep, logcheck
  • syslogd configuration
  • Logrotate configuration

Software Troubleshooting

  • strace and ltrace, ldd, lsof, strings
  • Library Dependencies
  • Kernel options in /proc/, sysctl, /etc/sysctl.conf
  • init and the process tree
  • top

Troubleshooting Login and Accounts

  • Logins with login, XDM, KDM, GDM, getty
  • Network Logins with Telnet, SSH, X, XDMCP, VNC
  • Users management with usermod
  • Login variables in /etc/login.defs, /etc/profile, /etc/bashrc, ~/.profile, ~/.bashrc


  • Schedule Jobs with Cron


This is a random list of filesystems.

  • zfs
  • btrfs
  • xfs
  • ext2
  • ext3
  • ext4
  • GlusterFS
  • MooseFS
  • Ceph
  • Lustre
  • Fraunhofer Parallel Cluster File System (FhGFS)
  • DRBD


Copying from the man page:

dracut creates an initial image used by the kernel for preloading the block device modules (such as IDE, SCSI or RAID) which are needed to access the root filesystem.

dracut reads configuration files in /usr/lib/modprobe.d/ and in /etc/modprobe.d/ by default, unless run in generic mode, in which case it ignores host-specific configuration in /etc/modprobe.d/.

Again, copying from the man page:

    -H, --hostonly
        Host-Only mode: Install only what is needed for booting the local 
        host instead of a generic host.

The default configuration is host-only. This is defined in /etc/dracut.conf, in the line:


Hello, I'm Marios Zindilis and this is my website. Opinions are my own. You also find me on LinkedIn and GitHub.

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