pfSense

The binding option is the correct workaround.

Failing that, see: http://doc.pfsense.org/index.php/Why_can%27t_I_query_SNMP,_use_syslog,_NTP,_or_other_services_initiated_by_the_firewall_itself_over_IPsec_VPN%3F

Nothing more can be done.

I tested PING normal
Firewall through
SNMP data is not ALL
This is normal?

[2.1-BETA1][root@pfsense.mec.hc]/root(3): ping S 172.30.34.254 192.168.139.254
PING 192.168.139.254 (192.168.139.254) from 172.30.34.254: 56 data bytes
64 bytes from 192.168.139.254: icmp_seq=0 ttl=64 time=45.884 ms
64 bytes from 192.168.139.254: icmp_seq=1 ttl=64 time=44.356 ms
64 bytes from 192.168.139.254: icmp_seq=2 ttl=64 time=44.798 ms
64 bytes from 192.168.139.254: icmp_seq=3 ttl=64 time=45.990 ms
64 bytes from 192.168.139.254: icmp_seq=4 ttl=64 time=45.901 ms
^C
-- 192.168.139.254 ping statistics ---
5 packets transmitted, 5 packets received, 0.0% packet loss
round-trip min/avg/max/stddev = 44.356/45.386/45.990/0.676 ms
[2.1-BETA1][root@pfsense.mec.hc]/root(4):

d:\>ping 192.168.139.254

Ping 192.168.139.254 (使用 32 位元組的資料):
回覆自 192.168.139.254: 位元組=32 時間=45ms TTL=63
回覆自 192.168.139.254: 位元組=32 時間=45ms TTL=63
回覆自 192.168.139.254: 位元組=32 時間=45ms TTL=63
回覆自 192.168.139.254: 位元組=32 時間=46ms TTL=63

192.168.139.254 的 Ping 統計資料:
封包: 已傳送 = 4，已收到 = 4, 已遺失 = 0 (0% 遺失)，
大約的來回時間 (毫秒):
最小值 = 45ms，最大值 = 46ms，平均 = 45ms

d:\>