SE VPN server is not responding to initial isakmp packets
Posted: Fri Aug 11, 2023 10:02 am
Hi,
I'm experiencing an issue to run IPSEC L2TP from android.
Server is "listening" on UDP 500 and 4500 aftes enabling L2TP.
udp UNCONN 0 0 192.168.100.5:500 0.0.0.0:* users:(("vpnserver",pid=460,fd=62))
udp UNCONN 0 0 192.168.100.5:4500 0.0.0.0:* users:(("vpnserver",pid=460,fd=63))
In TCPDump on SE server i can see requests for isakmp
11:54:51.510621 IP 37.225.20.254.5842 > 192.168.100.5.500: isakmp: parent_sa ikev2_init
11:54:52.597739 IP 37.225.20.254.5842 > 192.168.100.5.500: isakmp: parent_sa ikev2_init
But VPN server is not responding...
When L2TP is disabled below is right reaction of operating system
11:57:20.118299 IP 37.225.20.254.9005 > 192.168.100.5.500: isakmp: parent_sa ikev2_init
11:57:20.118392 IP 192.168.100.5 > 37.225.20.254: ICMP 192.168.100.5 udp port 500 unreachable, length 556
OS - Linux SE-VPN 6.1.0-10-amd64 #1 SMP PREEMPT_DYNAMIC Debian 6.1.38-2 (2023-07-27) x86_64 GNU/Linux
SE - version 4.42 Build 9798
The same was on CentOS.
May i ask You for help?
How to troubleshoot?
Thanks in advance.
RafaĆ
I'm experiencing an issue to run IPSEC L2TP from android.
Server is "listening" on UDP 500 and 4500 aftes enabling L2TP.
udp UNCONN 0 0 192.168.100.5:500 0.0.0.0:* users:(("vpnserver",pid=460,fd=62))
udp UNCONN 0 0 192.168.100.5:4500 0.0.0.0:* users:(("vpnserver",pid=460,fd=63))
In TCPDump on SE server i can see requests for isakmp
11:54:51.510621 IP 37.225.20.254.5842 > 192.168.100.5.500: isakmp: parent_sa ikev2_init
11:54:52.597739 IP 37.225.20.254.5842 > 192.168.100.5.500: isakmp: parent_sa ikev2_init
But VPN server is not responding...
When L2TP is disabled below is right reaction of operating system
11:57:20.118299 IP 37.225.20.254.9005 > 192.168.100.5.500: isakmp: parent_sa ikev2_init
11:57:20.118392 IP 192.168.100.5 > 37.225.20.254: ICMP 192.168.100.5 udp port 500 unreachable, length 556
OS - Linux SE-VPN 6.1.0-10-amd64 #1 SMP PREEMPT_DYNAMIC Debian 6.1.38-2 (2023-07-27) x86_64 GNU/Linux
SE - version 4.42 Build 9798
The same was on CentOS.
May i ask You for help?
How to troubleshoot?
Thanks in advance.
RafaĆ