pfSense

Adding an IPv4-mapped IPv6 address as a mobile IPsec DNS server on vpn_ipsec_mobile.php (ex: fd00::1.2.3.4) causes strongSwan to fail to load the configuration:

: grep dns /var/etc/ipsec/swanctl.conf
    dns = 10.6.0.1,198.51.100.1,8.8.8.8,fd00::1.2.3.4

: swanctl --load-all --file /var/etc/ipsec/swanctl.conf --debug 1
loaded certificate from '/var/etc/ipsec/x509/cert-3.crt'
loaded certificate from '/var/etc/ipsec/x509/cert-6.crt'
loaded certificate from '/var/etc/ipsec/x509ca/6c0118d9.0'
loaded certificate from '/var/etc/ipsec/x509ca/8d33f237.0'
loaded certificate from '/var/etc/ipsec/x509ca/b3b66f4e.0'
loaded certificate from '/var/etc/ipsec/x509crl/6000aa83711ba.crl'
loaded certificate from '/var/etc/ipsec/x509crl/5dc46362b276b.crl'
loaded certificate from '/var/etc/ipsec/x509crl/5e13900ddfcba.crl'
loaded certificate from '/var/etc/ipsec/x509crl/5dc481d149c58.crl'
loaded certificate from '/var/etc/ipsec/x509crl/5ddbf2404b7a4.crl'
loaded certificate from '/var/etc/ipsec/x509crl/59cd3ea6e0046.crl'
loaded ECDSA key from '/var/etc/ipsec/private/cert-6.key'
loaded RSA key from '/var/etc/ipsec/private/cert-3.key'
loaded ike secret 'ike-0'
loaded ike secret 'ike-2'
loaded ike secret 'ike-4'
loaded eap secret 'eap-5'
loaded eap secret 'eap-6'
no authorities found, 0 unloaded
loading pool 'mobile-pool-v4' failed: invalid attribute value for dns
loading pool 'mobile-pool-v6' failed: invalid attribute value for dns
loaded pool 'mobile-userpool-1'
loaded pool 'mobile-userpool-2'
loaded 2 of 4 pools, 2 failed to load, 0 unloaded

Removing fd00::1.2.3.4 and replacing it with an IPv6 address or another IPv4 address allows it to function normally.

Input validation should reject this since strongSwan won't parse it, and it should also be skipped in the backend to make sure an existing broken configuration won't prevent other parts from loading.