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9 votes

Configuring L2TP VPN to use with iOS 14 and macOS Big Sur

I was having this same problem after updating, change sha2-truncbug=yes > sha2-truncbug=no Using IPsec and xl2tpd for L2TP over IPsec server. The client is macOS Big Sur Version 11.0.1 ...
  • 216
8 votes

How to setup L2TP IPsec VPN server on Windows Server 2008 R2?

1. Check L2TP ports existence First check whether there are actually L2TP port configured in Routing and Remote Access (RRAS). Click Start, click Administrative Tools, and then click Routing and ...
7 votes

Is there a speed and performance difference between VPNs (L2TP, etc.) vs. port forwarding?

Port forwarding would be quicker, but it would be less secure, in the sense that there is no confidentiality, or integrity. If you don't care then it is not a problem. Any VPN or tunnelling will add ...
  • 363
5 votes

How do I bypass my VPN when making requests to IPs in my local network?

The solution was to modify the routing table in such a way that IPs in local network are routed via the default gateway: sudo ip route add via Where is the ...
4 votes

Connected to Windows Server 2016 VPN on AWS but could not ping resources in VPC

Finally found the correct steps on how to create a VPN on Windows Server 2016 in AWS. Once connected, the client is able to access resources within the VPC and still access the Internet. Here's the ...
3 votes

How to veryify if VPN network encrypt data correctly in Windows 7?

Your "Local connection" is your regular (physical) connection over which the IPsec VPN tunnel is built. Disabling that interface will completely isolate your windows client from the network; thus the ...
  • 5,607
2 votes

Simple L2TP/IPsec server not working (openswan, xl2tpd, Ubuntu, Windows)

I had similar problem. My server doesn't NAT, so this piece is not needed so removed it: conn L2TP-PSK-NAT rightsubnet=vhost:%priv also=L2TP-PSK-noNAT And when that's done NAT Traversel must be set ...
  • 377
2 votes

Cannot connect to my L2TP IPSec VPN

Im sorry about my English. I have same problem and after..... many hours........... I see a option in the Networks Interfaces..... need edit the Interface LAN when you have the connection Server VPN ...
  • 21
2 votes

What are the ports needed for L2TP VPN on Mac OS X Server 5.0.15?

First off, what protocol of VPN are you using? OS X Server offers both L2TP (over IPSEC) and PPTP protocols, both of which use different ports. For L2TP you need ports 500 (UDP), 1701 (UDP), and ...
  • 403
2 votes

RSTP over tunnel?

Unless it is absolutely necessary, which I doubt, running layer-2 over a WAN is a really bad idea. STP will require all sorts of tweaks to work correctly with the increased latency. You need to ...
  • 3,213
2 votes

Windows RRAS VPN failing to set options on Mac L2TP clients due to DHCP relay discarding packets

As it turns out, the defaults for the DHCP relay agent simply don't work for some L2TP clients. When you set up an interface for DHCP relaying in RRAS (on the "Internal" interface, where VPN ...
2 votes

How to route traffic between L2TP/IPSec and WireGuard tunnels?

You need to add route on the L2TP VPN clients, which tells that packets to should be sent via Also, you need to add route on Wireguard server, which tells that packets to ...
2 votes

Is there a speed and performance difference between VPNs (L2TP, etc.) vs. port forwarding?

I don't think you'd have a relevant performance gain for this specific example. Nonetheless, bear in mind a layer 2 to VPN would handle more traffic, like broadcasts, ARP packets, and NetBIOS packets. ...
2 votes

The specified protocol identifier is not known to the router Windows server 2022

I've found one thread and one article online regarding this error message - both suggest the issue is IPv6 being disabled on the VPN server - have you checked for that? It seems like that prevents the ...
1 vote

Diagnose L2TP VPN connection failures in CentOS 7

From the logs, IPsec phase 1 (main mode) is successful, but phase 2 (quick mode) failed. Perhaps the VPN server doesn't use Perfect Forward Secrecy (PFS) for phase 2 (quick mode). So try the "Disable ...
1 vote

TP-LINK TL-MR6400 IPSEC L2TP VPN tunnel with GCP server

The solution you are trying to achieve is fine, just keep in mind that that workaround might increase your bandwidth and latency. As a side note, I am biased in favor of OpenWRT, but that firmware ...
  • 371
1 vote

How to stop Windows Filtering Platform blocking ICMP packets for legitimate RDP traffic over L2TP tunnel?

The partial screen load before failure looks to me like a MTU size mismatch. It is common for tunnels to have a smaller MTU then 1500. As a test, temporarily reduce the configured MTU of your RDP ...
  • 61
1 vote

VPN into router behind a Sonicwall

Make sure in the sonicwall, in the VPN user configuration, that those users are allowed to access the 192.168.100.X network. You did correctly by adding the firewall rules, but you have VPN policy ...
  • 16.5k
1 vote

strongSwan 5.6.2 and xl2tp 1.3.12 on Ubuntu 18.04 SA established but no traffic

There is a known bug in Linux kernel 4.15, which Ubuntu 18.04 ships, that causes the IP address to change in this way. It was caused by 5efec5c655dd ("xfrm: Fix eth_hdr(skb)->h_proto to reflect inner ...
  • 3,870
1 vote

How to forward IPsec VPN with iptables

I recommend you do this eth0 is your "public interface" /sbin/iptables -t nat -A POSTROUTING -o eth0 -j MASQUERADE active routing /bin/echo 1 > /proc/sys/net/ipv4/ip_forward set nat to ...
1 vote

How do I get an L2TP Foxpass VPN connection working in Windows 10?

Windows defaults the L2TP connection to use CHAP, but you need to go into the adapter settings and switch it to PAP. That, along with the AssumeUDPEncapsulationContextOnSendRule, should get this ...
  • 36
1 vote

Windows VPN client - how to make it connect to a different port?

Unfortunately, Windows VPN Client is not capable of changing the target TCP port of VPN connection. I would recommend you to setup a second IP address on your CentOS box and assign different xl2tpd ...
  • 6,151
1 vote

Configuring L2TP/IPSec on Cisco Router 2911

It seems you have a misconfiguration between yours hash algorithm : The conf of your router : ... crypto isakmp policy 20 encr 3des authentication pre-share group 2 hash md5 ... And ...
  • 1,315
1 vote

L2TP VPN without certificates between Windows XP and ZyWALL USG 200

The problem is not the IKE Phase 1 configuration, but the Local Policy in the connection settings (not shown in my question). The Local Policy must be the public interface IP in my case, and it wasn't....
1 vote

Cisco IPSec Issue with Windows 10

Though I'm not sure that the VPN type was identical, when I got the error message The L2TP connection attempt failed because the security layer encountered a processing error during initial ...
  • 434
1 vote

How to configure Fortigate 60D as L2PT/IPSEC client

You can specify the connection type in the GUI under "Remote Gateway". Setting it to "Dialup User" is what you want. You can also use the "type" option in the phase1-interface table. conf vpn ipsec ...
  • 224
1 vote

How to proxy a l2tp server?

I highly doubt this is possible. L2tp works over udp/1701, and it's not proxiable. Furthermore, you don't need to proxy it, because pure l2tp is perfectly able to cross NATs. After all, your request ...
  • 8,500
1 vote

Setting up site-to-site IPsec in bridged mode

It is my personal experience that this is possible but not recommended. In fact, I want to communicate to you that you should never ever use this configuration. Let me explain Layer 2 bridge mode is ...
  • 600
1 vote

Why does VNC viewer on Mac Book Pro report RFB protocol error when connecting to AWS over L2TP?

The most likely cause of this setting if you are using a VPN would be an MTU size set too large, causing packet fragmentation. When this occurs some protocols will encounter problems, and is known to ...
1 vote

VPN for Video stream

I never used RTP but AFAIU, your should probably increase the buffering/latency on the receving side at the RTP level: the RTP has a timestamp packet which can be used to reorder the packets. If you ...
  • 1,643

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