# s ifconfig lo create
lo3
# s jail -c name=test persist vnet vnet.interface="lo3"
# s jexec test sysctl net.inet.tcp.msl=100
net.inet.tcp.msl: 30000 -> 100
# s jexec test sysctl net.inet.tcp.msl
net.inet.tcp.msl: 100
# sysctl net.inet.tcp.msl
net.inet.tcp.msl: 30000