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Tigran K.

@tkhachik2

0.0

1.6

100%

Network and System Engineer (CCNA, CCNP)

$29 USD / Hour

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Germany (6:18 AM)

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Joined on January 25, 2012

$29 USD / Hour

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Skillful network and system engineer (active CCNP certification) with good analytical, troubleshooting, and communication skills. Over 7 years' experience in configuring and maintaining highly available computer networks and network related services on Cisco devices and GNU/Linux servers. Profficient in configuring dynamic routing protocols (BGP, OSPF, EIGRP), VPN technologies (IPSec, GRE), IPv6, STP, etherchannel, VTP, VRRP, HSRP; Cisco routers and switches (IOS/CatOS), ASA appliances, GNU/Linux ditributions including Red Hat, Debian, CentOS, Fedora, Ubuntu, Slackware (iptables, openswan, racoon, openvpn, BIND, Squid, Apache, DHCP, TFTP, vsftpd, keepalived etc).

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Portfolio

To provide a secure communication channels between the main site and remote sites, branches, external partners or teleworkers this IPSec VPN infrastructure has been designed and implemented. The main site uses two Cisco 3800 series routers with HSRP while remote sites and branches have 1800 series.

VPN Infrastructure

To serve as a web proxy Squid has been configured on Debian servers. The active-passive redundancy has been implemented by means of keepalived. Squid configuration includes access restrictions and delay pools based on source IP addresses, destination URL, and authentication (to connect to other cache peer proxy).

Redundant Web Proxy Servers

To handle all requests from production network and external queries the name servers and resolvers have been separated.
- A single master name server updates 4 slaves with AXFR transactions.
- All slaves have been configured to serve requests for about 1200 public domains.
- 2 views have been created for internal and external DNS clients.
- 4 resolvers are placed behind 2 vips to optimize load sharing and provide high availability.
- All systems are Debian servers with BIND.

Production DNS infrastructure

All firewalls and routers except the vpn router were GNU/Linux servers (Slackware and later migrated to Fedora) with shorewall, iptables and iputils. Different route tables with PBR were created to utilize two internet links and one VPN connection. The redundancy (active-passive) of edge routers and firewalls was achieved by means of keepalived.

Linux routers and firewalls

To connect several locations IPSec tunnels were used over public Internet links. Over the secure channels an OSPF hierarchy was built. The backbone are contained the main production data center and services. The main purpose of this infrastructure was providing secure remote management of those services. At the same time it was used also by office IT systems (Windows AD, MS Exchange). ABR-s were Cisco 1721 and the main data center had Cisco 6513.

OSPF over IPSec links

VPN Infrastructure

Redundant Web Proxy Servers

Production DNS infrastructure

Linux routers and firewalls

OSPF over IPSec links

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