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Archive for the ‘VPN’ Category

PPTP Pass-through through Juniper NS 5GT Firewall

July 16th, 2010 rsivanandan No comments

Got a question on this one in my comments page and hence thought of putting it together. Say there is a PPTP server residing on the trust side of your NS firewall (applicable to all/most of the NS firewalls running Screen OS). For simplicity, assuming that the device is in NAT mode and you want to allow connections coming from internet for PPTP VPN, follow the steps here;

First create a custom service to address the PPTP requirement (This is Microsoft windows specific);

set service CustomPPTP group "other" 47 src 2048-2048 dst 2048-2048

set service CustomPPTP + tcp src 0-65535 dst 1723-1723

The first line above creates a custom service named “CustomPPTP” with protocol number 47 (GRE) with source/destination port as 2048.

The second line adds to the same service for PPTP (port 1723 TCP).

 

Then the next step would be to NAT the internal PPTP server to publically accessible server using a public ip address. Here we’d use the same address assigned on the untrust interface (single public ip available scenario);

set vip multi-port

set interface ethernet0/0 vip 2048 CustomPPTP 10.1.1.10

 

The first line above states that it is a multi-port VIP. Normally a VIP listens only on a single port, if a single ip address is used and you want to have multiple ports forwarded, multi-port VIP is needed.

The second line above sets a VIP for port 2048 for the internal server (PPTP Server) 10.1.1.10 (assuming the ip of the internal PPTP server to be this).

almost done; the only thing pending is a policy to allow traffic to pass through this condition;

set policy from untrust to trust "any" "VIP::1" "CustomPPTP" permit

The above policy allows any machine from untrust zone (internet) to connect to VIP address (trust zone) for the service “CustomPPTP”.

Just save the configuration and you should have it working just fine…

Juniper KB Link

Categories: Juniper, VPN, Windows Tags:

MPLS and Loopback Address

February 21st, 2009 rsivanandan 1 comment

 

Our team just started working on technology involving MPLS and stuff, so we were talking about MPLS networks, then came a question as to why do we always see loopback addresses in examples and is it like a strict requirement? We couldn’t find a solid answer or answers, owing to the fact that we are a bunch of security experts just landed into this MPLS

 

So the question is, Is it a must to have Loopback addresses for MPLS to work? Well, I got the following from  [Here]

 

"Loopback" IP address

Although not a strict requirement, it is advisable to configure routers participating in MPLS network with "loopback" IP addresses (not attached to any real network interface) to be used by LDP to establish sessions.

This serves 2 purposes:

    • As there is only one LDP session between any 2 routers, no matter how many links connect them, loopback IP address ensures that LDP session is not affected by interface state or address changes
    • Use of loopback address as LDP transport address ensures proper penultimate hop popping behaviour when multiple labels are attached to packet as in case of VPLS
 

Is there any other reason that you think should be there? Would appreciate if you could comment.

Categories: Tech in general, VPN Tags:

VPN to Juniper Firewall – using XP Client

June 8th, 2008 rsivanandan No comments

 

  It is advisable to use the Netscreen-Remote that comes as the vpn client, however if one has to use XP client for connecting to a Juniper Firewall, here is how to do;

This example talks about L2TP over IPSEC { GO }

Categories: Juniper, VPN Tags:

VPN between Cisco PIX and Juniper Netscreen Firewall

May 29th, 2008 rsivanandan 2 comments

 

Found out today that Cisco has a configuration guide for VPN between PIX firewall to a Juniper Netscreen Firewall

{Click to Go}

Categories: Juniper, VPN Tags:

Juniper SSG-Cisco PIX VPN Configuration

December 18th, 2007 rsivanandan 1 comment

Its been quite some time I’m wanting to post such a configuration. I helped with one such question in Experts-Exchange and sought permission from the author to post the working configuration once the VPN was up and running. Below would be the configuration of working SSG-PIX VPN with the consent of the author. Obviously the public ip addresses are masked.

To give a background, SSG is at the main office, PIX being at remote office. The VPN is built between 10.10.12.0 network to 10.10.7.0 network in the following configuration;

SSG 140 Configuration:-

   1: JUNIPER (MAIN OFFICE)--->
   2: set clock timezone -5
   3: set vrouter trust-vr sharable
   4: set vrouter "untrust-vr"
   5: exit
   6: set vrouter "trust-vr"
   7: unset auto-route-export
   8: exit
   9: set auth-server "Local" id 0
  10: set auth-server "Local" server-name "Local"
  11: set auth default auth server "Local"
  12: set auth radius accounting port 1646
  13: set admin name "admin"
  14: set admin password "XYZ123"
  15: set admin http redirect
  16: set admin auth timeout 10
  17: set admin auth server "Local"
  18: set admin format dos
  19: set vip multi-port
  20: set zone "Trust" vrouter "trust-vr"
  21: set zone "Untrust" vrouter "trust-vr"
  22: set zone "DMZ" vrouter "trust-vr"
  23: set zone "VLAN" vrouter "trust-vr"
  24: set zone id 100 "DMZ-WAN"
  25: set zone "Untrust-Tun" vrouter "trust-vr"
  26: set zone "Trust" tcp-rst 
  27: set zone "Untrust" block 
  28: unset zone "Untrust" tcp-rst 
  29: set zone "MGT" block 
  30: set zone "DMZ" tcp-rst 
  31: set zone "VLAN" block 
  32: unset zone "VLAN" tcp-rst 
  33: set zone "DMZ-WAN" block 
  34: unset zone "DMZ-WAN" tcp-rst 
  35: set zone "Trust" screen icmp-flood
  36: set zone "Trust" screen udp-flood
  37: set zone "Trust" screen winnuke
  38: set zone "Trust" screen port-scan
  39: set zone "Trust" screen ip-sweep
  40: set zone "Trust" screen tear-drop
  41: set zone "Trust" screen ping-death
  42: set zone "Trust" screen ip-filter-src
  43: set zone "Trust" screen land
  44: set zone "Trust" screen syn-frag
  45: set zone "Trust" screen tcp-no-flag
  46: set zone "Trust" screen unknown-protocol
  47: set zone "Trust" screen ip-bad-option
  48: set zone "Trust" screen ip-record-route
  49: set zone "Trust" screen ip-timestamp-opt
  50: set zone "Trust" screen ip-security-opt
  51: set zone "Trust" screen ip-loose-src-route
  52: set zone "Trust" screen ip-strict-src-route
  53: set zone "Trust" screen ip-stream-opt
  54: set zone "Trust" screen icmp-fragment
  55: set zone "Trust" screen icmp-large
  56: set zone "Trust" screen syn-fin
  57: set zone "Trust" screen fin-no-ack
  58: set zone "Trust" screen limit-session source-ip-based
  59: set zone "Trust" screen syn-ack-ack-proxy
  60: set zone "Trust" screen block-frag
  61: set zone "Trust" screen limit-session destination-ip-based
  62: set zone "Trust" screen component-block exe
  63: set zone "Trust" screen icmp-id
  64: set zone "Trust" screen ip-spoofing drop-no-rpf-route
  65: set zone "Untrust" screen tear-drop
  66: set zone "Untrust" screen syn-flood
  67: set zone "Untrust" screen ping-death
  68: set zone "Untrust" screen ip-filter-src
  69: set zone "Untrust" screen land
  70: set zone "V1-Untrust" screen tear-drop
  71: set zone "V1-Untrust" screen syn-flood
  72: set zone "V1-Untrust" screen ping-death
  73: set zone "V1-Untrust" screen ip-filter-src
  74: set zone "V1-Untrust" screen land
  75: set interface "ethernet0/0" zone "Trust"
  76: set interface "ethernet0/1" zone "DMZ"
  77: set interface "ethernet0/2" zone "Untrust"
  78: set interface "ethernet0/3" zone "DMZ-WAN"
  79: set interface "tunnel.1" zone "Untrust"
  80: set interface ethernet0/0 ip 10.10.7.2/24
  81: set interface ethernet0/0 route
  82: unset interface vlan1 ip
  83: set interface ethernet0/1 ip 10.10.9.1/24
  84: set interface ethernet0/1 route
  85: set interface ethernet0/2 ip X.Y.Z.98/27
  86: set interface ethernet0/2 route
  87: set interface ethernet0/3 ip 10.10.99.0/24
  88: set interface ethernet0/3 route
  89: set interface tunnel.1 ip unnumbered interface ethernet0/2
  90: unset interface vlan1 bypass-others-ipsec
  91: unset interface vlan1 bypass-non-ip
  92: set interface ethernet0/0 ip manageable
  93: unset interface ethernet0/1 ip manageable
  94: set interface ethernet0/2 ip manageable
  95: unset interface ethernet0/3 ip manageable
  96: unset interface ethernet0/0 manage snmp
  97: set interface ethernet0/0 manage mtrace
  98: unset interface ethernet0/1 manage ping
  99: set interface ethernet0/2 manage ping
 100: set interface ethernet0/2 manage ssh
 101: set interface ethernet0/2 manage telnet
 102: set interface ethernet0/2 manage ssl
 103: set interface ethernet0/2 manage web
 104: set interface ethernet0/2 manage mtrace
 105: set interface vlan1 manage mtrace
 106: set interface "ethernet0/2" mip X.Y.Z.106 host 10.10.7.106 netmask 255.255.255.255 vr "trust-vr"
 107: set interface "ethernet0/2" mip X.Y.Z.109 host 10.10.7.200 netmask 255.255.255.255 vr "trust-vr"
 108: set interface "ethernet0/2" mip X.Y.Z.100 host 10.10.7.100 netmask 255.255.255.255 vr "trust-vr"
 109: set interface "ethernet0/2" mip X.Y.Z.101 host 10.10.7.206 netmask 255.255.255.255 vr "trust-vr"
 110: set interface "ethernet0/2" mip X.Y.Z.103 host 10.10.7.103 netmask 255.255.255.255 vr "trust-vr"
 111: set interface "ethernet0/2" mip X.Y.Z.108 host 10.10.7.208 netmask 255.255.255.255 vr "trust-vr"
 112: set interface "ethernet0/2" mip X.Y.Z.121 host 10.10.7.121 netmask 255.255.255.255 vr "trust-vr"
 113: set interface "ethernet0/2" mip X.Y.Z.115 host 10.10.7.115 netmask 255.255.255.255 vr "trust-vr"
 114: set interface "ethernet0/2" mip X.Y.Z.125 host 10.10.7.122 netmask 255.255.255.255 vr "trust-vr"
 115: set interface "ethernet0/0" webauth 
 116: unset flow no-tcp-seq-check
 117: set flow tcp-syn-check
 118: set domain econium
 119: set pki authority default scep mode "auto"
 120: set pki x509 default cert-path partial
 121: set dns host dns1 66.153.50.66 src-interface ethernet0/2
 122: set dns host dns2 64.80.0.162 src-interface ethernet0/2
 123: set dns host dns3 64.80.32.128 src-interface ethernet0/2
 124: set dns host schedule 06:28
 125: set address "Trust" "10.10.7.0/24" 10.10.7.0 255.255.255.0
 126: set address "Trust" "10.10.7.106/24" 10.10.7.106 255.255.255.0
 127: set address "Trust" "10.10.7.117/24" 10.10.7.117 255.255.255.0
 128: set address "Trust" "Office LAN" 10.10.0.0 255.255.0.0
 129: set address "Trust" "Trust_LAN" 10.10.7.0 255.255.255.0
 130: set address "Untrust" "10.10.12.0/24" 10.10.12.0 255.255.255.0
 131: set address "Untrust" "X.Y.Z.117/30" X.Y.Z.117 255.255.255.252
 132: set address "Untrust" "W-Remote" 10.10.12.0 255.255.255.0
 133: set address "DMZ-WAN" "Wireless" 10.10.99.0 255.255.255.0 "Wireless"
 134: set ike gateway "W-Remote GW" address A.B.C.42 Main outgoing-interface "ethernet0/2" preshare "myxlplyt" proposal "pre-g2-3des-sha"
 135: set ike respond-bad-spi 1
 136: unset ike ikeid-enumeration
 137: unset ike dos-protection
 138: unset ipsec access-session enable
 139: set ipsec access-session maximum 5000
 140: set ipsec access-session upper-threshold 0
 141: set ipsec access-session lower-threshold 0
 142: set ipsec access-session dead-p2-sa-timeout 0
 143: unset ipsec access-session log-error
 144: unset ipsec access-session info-exch-connected
 145: unset ipsec access-session use-error-log
 146: set vpn "W-Remote VPN" gateway "W-Remote GW" no-replay tunnel idletime 0 proposal "g2-esp-3des-sha" 
 147: set vpn "W-Remote VPN" id 1 bind interface tunnel.1
 148: set url protocol websense
 149: exit
 150: set anti-spam profile ns-profile
 151:  set sbl default-server enable
 152:  set default action tag subject "*** [SPAM] ***"
 153: exit
 154: set vpn "W-Remote VPN" proxy-id local-ip 10.10.7.0/24 remote-ip 10.10.12.0/24 "ANY" 
 155: set policy id 34 from "Trust" to "Untrust"  "10.10.7.0/24" "10.10.12.0/24" "ANY" permit log 
 156: set policy id 34
 157: set log session-init
 158: exit
 159: set policy id 33 from "Untrust" to "Trust"  "10.10.12.0/24" "10.10.7.0/24" "ANY" permit log 
 160: set policy id 33
 161: set log session-init
 162: exit
 163: set policy id 21 from "Untrust" to "Trust"  "Any" "MIP(X.Y.Z.106)" "ANY" permit log 
 164: set policy id 21
 165: exit
 166: set policy id 1 name "Internet Access" from "Trust" to "Untrust"  "Office LAN" "Any" "HTTP" nat src permit log url-filter 
 167: set policy id 1
 168: set log session-init
 169: exit
 170: set policy id 2 from "Trust" to "Untrust"  "Office LAN" "Any" "HTTPS" nat src permit log 
 171: set policy id 2
 172: exit
 173: set policy id 5 from "Trust" to "DMZ"  "Office LAN" "Any" "ANY" nat src permit log 
 174: set policy id 5
 175: exit
 176: set policy id 6 name "Deny All - DMZ" from "Untrust" to "DMZ"  "Any" "Any" "ANY" deny log 
 177: set policy id 6
 178: exit
 179: set policy id 7 from "Trust" to "Untrust"  "Office LAN" "Any" "DNS" nat src permit 
 180: set policy id 7
 181: exit
 182: set policy id 8 from "Trust" to "Untrust"  "Office LAN" "Any" "FTP" nat src permit 
 183: set policy id 8
 184: exit
 185: set policy id 9 from "Trust" to "Untrust"  "Office LAN" "Any" "POP3" nat src permit 
 186: set policy id 9
 187: exit
 188: set policy id 10 from "Trust" to "Untrust"  "Office LAN" "Any" "SMTP" nat src permit log 
 189: set policy id 10
 190: exit
 191: set policy id 11 name "Wireless Access" from "DMZ-WAN" to "Untrust"  "Wireless" "Any" "DNS" nat src permit log 
 192: set policy id 11
 193: set service "FTP"
 194: set service "HTTP"
 195: set service "HTTPS"
 196: set service "PING"
 197: set service "POP3"
 198: set service "SMTP"
 199: set service "VNC"
 200: exit
 201: set policy id 13 name "VNC" from "Trust" to "Untrust"  "Office LAN" "Any" "VNC" nat src permit log 
 202: set policy id 13
 203: exit
 204: set policy id 14 name "Ping" from "Trust" to "Untrust"  "Office LAN" "Any" "PING" nat src permit log 
 205: set policy id 14
 206: exit
 207: set policy id 31 from "Trust" to "Untrust"  "Any" "Any" "ANY" nat src permit log 
 208: set policy id 31
 209: exit
 210: set policy id 32 from "Trust" to "Untrust"  "Office LAN" "Any" "ANY" nat src permit log 
 211: set policy id 32
 212: exit
 213: set nsmgmt bulkcli reboot-timeout 60
 214: set ssh version v2
 215: set ssh enable
 216: set config lock timeout 5
 217: set ntp server "0.0.0.0"
 218: set ntp server backup1 "0.0.0.0"
 219: set ntp server backup2 "0.0.0.0"
 220: set snmp port listen 161
 221: set snmp port trap 162
 222: set vrouter "untrust-vr"
 223: exit
 224: set vrouter "trust-vr"
 225: unset add-default-route
 226: set route 10.10.12.0/24 interface tunnel.1 preference 20
 227: set route 0.0.0.0/0 interface ethernet0/2 gateway X.Y.Z.97 preference 20 metric 10
 228: exit
 229: set vrouter "untrust-vr"
 230: exit
 231: set vrouter "trust-vr"
 232: exit

PIX Configuration:-

   1: CISCO PIX (REMOTE OFFICE) -->
   2: PIX Version 6.3(5)
   3: interface ethernet0 auto
   4: interface ethernet1 auto
   5: nameif ethernet0 outside security0
   6: nameif ethernet1 inside security100
   7: enable password ABCDE encrypted
   8: passwd abcde encrypted
   9: hostname W-Remote
  10: domain-name pix
  11: clock timezone EST -5
  12: clock summer-time EDT recurring
  13: fixup protocol dns maximum-length 512
  14: fixup protocol ftp 21
  15: fixup protocol h323 h225 1720
  16: fixup protocol h323 ras 1718-1719
  17: fixup protocol http 80
  18: fixup protocol http 8080
  19: fixup protocol pptp 1723
  20: fixup protocol rsh 514
  21: fixup protocol rtsp 554
  22: fixup protocol sip 5060
  23: fixup protocol sip udp 5060
  24: fixup protocol skinny 2000
  25: fixup protocol smtp 25
  26: fixup protocol sqlnet 1521
  27: fixup protocol tftp 69
  28: names
  29: access-list acl_out permit icmp any any
  30: access-list 101 permit ip 10.10.12.0 255.255.255.0 10.10.7.0 255.255.255.0
  31: access-list nonat permit ip 10.10.12.0 255.255.255.0 10.10.7.0 255.255.255.0
  32: access-list cap permit ip host 10.10.12.112 host 10.10.7.117
  33: access-list cap permit ip host 10.10.7.117 host 10.10.12.112
  34: pager lines 24
  35: logging on
  36: logging monitor debugging
  37: logging buffered debugging
  38: logging history errors
  39: mtu outside 1500
  40: mtu inside 1500
  41: ip address outside A.B.C.42 255.255.255.248
  42: ip address inside 10.10.12.2 255.255.255.0
  43: ip audit info action alarm
  44: ip audit attack action alarm
  45: pdm location 10.10.12.0 255.255.255.255 inside
  46: pdm location 10.10.7.0 255.255.255.0 outside
  47: pdm location 10.10.12.0 255.255.255.0 outside
  48: pdm logging informational 100
  49: pdm history enable
  50: arp timeout 14400
  51: global (outside) 1 interface
  52: nat (inside) 0 access-list nonat
  53: nat (inside) 1 10.10.12.0 255.255.255.0 0 0
  54: access-group acl_out in interface outside
  55: route outside 0.0.0.0 0.0.0.0 A.B.C.42 1
  56: timeout xlate 0:05:00
  57: timeout conn 1:00:00 half-closed 0:10:00 udp 0:02:00 rpc 0:10:00 h225 1:00:00
  58: timeout h323 0:05:00 mgcp 0:05:00 sip 0:30:00 sip_media 0:02:00
  59: timeout sip-disconnect 0:02:00 sip-invite 0:03:00
  60: timeout uauth 0:05:00 absolute
  61: aaa-server TACACS+ protocol tacacs+
  62: aaa-server TACACS+ max-failed-attempts 3
  63: aaa-server TACACS+ deadtime 10
  64: aaa-server RADIUS protocol radius
  65: aaa-server RADIUS max-failed-attempts 3
  66: aaa-server RADIUS deadtime 10
  67: aaa-server LOCAL protocol local
  68: http server enable
  69: http 10.10.12.0 255.255.255.0 inside
  70: no snmp-server location
  71: no snmp-server contact
  72: snmp-server community public
  73: no snmp-server enable traps
  74: no floodguard enable
  75: sysopt connection permit-ipsec
  76: sysopt connection permit-pptp
  77: sysopt connection permit-l2tp
  78: sysopt ipsec pl-compatible
  79: crypto ipsec transform-set ESP-3DES-SHA esp-3des esp-sha-hmac
  80: crypto map pie 1 ipsec-isakmp
  81: crypto map pie 1 match address 101
  82: crypto map pie 1 set peer X.Y.Z.98
  83: crypto map pie 1 set transform-set ESP-3DES-SHA
  84: crypto map pie interface outside
  85: isakmp enable outside
  86: isakmp key ******** address X.Y.Z.98 netmask 255.255.255.0
  87: isakmp policy 1 authentication pre-share
  88: isakmp policy 1 encryption 3des
  89: isakmp policy 1 hash sha
  90: isakmp policy 1 group 2
  91: isakmp policy 1 lifetime 3600
  92: telnet 10.10.12.0 255.255.255.0 inside
  93: telnet 10.10.7.0 255.255.255.0 inside
  94: telnet timeout 30
  95: ssh 0.0.0.0 0.0.0.0 outside
  96: ssh timeout 60
  97: management-access inside
  98: console timeout 0
  99: terminal width 80
 100: : end
Categories: Juniper, VPN Tags:

Split-Tunneling in PIX – How To ?

August 4th, 2007 rsivanandan No comments

There have been so many questions about how to configure split-tunneling on PIX. So right to the point;

Internal Network :: 10.0.4.0/24

VPN Pool :: 10.1.4.0/24

Config goes here;

access-list nonat permit ip 10.0.4.0 255.255.255.0 10.1.4.0 255.255.255.00

access-list split permit ip 10.0.4.0 255.255.255.0 10.1.4.0 255.255.255.0

nat(inside) 0 access-list nonat

vpngroup <GroupName> split-tunnel split

Now it goes into respective configuration section of nat and vpngroup configuration sections. Question is why 2 access-list ? ‘nonat’ and ‘split’

Cisco recommends it to be that way and otherwise found running into problems at times.

Categories: VPN Tags:

Site-To-Site VPN on Netscreen/Juniper Firewalls

July 29th, 2007 rsivanandan 17 comments

One of the amazing functionality of Juniper firewalls are the CLI easiness of creating and maintaining configurations, one such impressive example is VPN Configuration;

Say, we have 2 working Juniper firewalls and if we want to configure site to site vpn tunnels, then it would be as simple as 3 commands. Lets see how difficult it is;

First create a tunnel Interface :

set interface tunnel.1 zone <Zone>

set interface tunnel.1 ip unnumbered interface <Interface>

Create VPN parameters:

set ike <Gateway-Name> address <Remote Peer IP> <Mode> outgoing-interface <Interface-Name> preshare “Key” proposal <Propasal>

set vpn <VPN-Name> gateway <IKE-Gateway> sec-level compatible

set vpn <VPN-Name> bind interface <Tunnel-Interface>

Create a route to send the traffic over VPN:

set route <Remote-Network>/<Mask> interface tunnel.1

Example:

SiteA-Network———-Firewall-1————————-Firewall-2————SiteB-Network

Firewall-1  [ethernet0/1 - outside interface in zone 'untrust' , 1.1.1.1/30]

Firewall-2 [ethernet0/1 - outside interface in zone 'untrust', 2.2.2.2/30]

Firewall-1 [Internal Network is 20.20.20.0/24]

Firewall-2 [ Internal Network is 10.10.10.0/24]

So the configuration would look like this;

###################################################################

set interface tunnel.1 zone untrust

set interface tunnel.1 ip unnumbered interface ethernet0/1

set ike “ToSiteB” address 2.2.2.2 main outgoing-interface ethernet0/1 preshare PASSWORD proposal pre-g2-3des-sha

set vpn “TOSITEB-VPN” gateway “ToSiteB” sec-level compatible

set vpn “TOSITEB-VPN” bind interface tunnel.1

set route 10.10.10.0/24 interface tunnel.1

###################################################################

Categories: Juniper, VPN Tags:

Split-Tunneling Good or Bad ?

July 19th, 2007 rsivanandan No comments

In the VPN configuration this seems to be a host discussion; so here we go

There are 2 options of internet traffic for the VPN users;

  1. Split-Tunneling enabled :: This means all the corporate traffic goes through the vpn tunnel and all the internet (local browsing etc) goes through the user’s local internet connection which improves the browsing speed/experience for the end user.
  2. Split-Tunneling disabled :: This means all the corporate traffic and local user traffic to internet traverse over the vpn tunnel and the internet traffic first goes to the vpn end-point and then exits to internet

Now, point 1 seems to be interesting to some security professionals for the reason that, while connected through VPN there is no local interaction and thus no ” security risk “. The argument being while connected to the corporate through VPN, the public internet is secluded and thus there is more security in terms of somebody/something from internet gets to the corporate!

Well, let me see; the way I see it – First of all it makes the internet browsing poor for the end user who is probably browsing more but still is *ON* VPN just for mail checking in the late evening (If that is happening :-) ). Now security-wise, does it mean by just disabling the split-tunneling, an administrator can be assured that the user won’t harm the corporate ? I don’t think so;

How About users’ machine infected with a Virus/Trojan/Some Crap, whether you have enabled split-tunneling or not, this is going to enter corporate ???? YES.

So what security are we talking about ?

The best approach would be to have Network Access/Admission Control which is integrated with an AntiVirus/AntiSpyware/IPS and Firewall module.

Now is there something obvious I’m not seeing here? May be somebody can shed some light and I would really appreciate that!

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Windows VPN Split-Tunnel

July 12th, 2006 rsivanandan No comments

To allow split-tunnel feature while connected through Windows VPN, you can enable or disable to have all the internet traffic go through VPN. Security measures is your choice.

How to do it ?

Onthe client machine go :
control panel | network connections | right click on the VPN/virtual adapter and choose properties | Networking | TCP/IP -properties | advanced | general | un-check “use default gateway on remote network”

Categories: VPN Tags:

MTU settings for VPN

July 9th, 2006 rsivanandan 5 comments

I thought I will put this info on this here, so that everytime I answer a question, don’t have to type it all and just link to here;

Basically one of the biggest problems encountered with ExchangeServer and Outlook client when they are connected over a IPSec VPN, it doesn’t work very well. As a solution, this is what I’ve always suggested and proved to be of use too.

1. When you connect through VPN, first find out what is the best MTU size for you to talk to your corporate. How you can do this is simple; Connect to VPN and then,

ping -l 1400 -f <insideipofServer>

what we are doing here is to set the mtu to 1400 and also set ‘don’t fragment’. So if it is possible to send the packet without fragmenting then it would go through otherwise you’ll get a reply saying ‘don’t fragment bit set and so cannot proceed’. You are in-effect finding the Path MTU.

Then slow start reducing the 1400 to 1350, 1300 etc and see when you can ping without any problems and that should be your MTU.

2. Also make sure you add the servername to ip resolution in your hosts file.

That should take care of your problem in most of the scenarios. Now how to change the MTU size on the network adaptor?

The MTU for Windows 2000/XP/2003 network interfaces can be configured here:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters\Interfaces\{Interface GUID}\MTU

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