Check what Linux kernel modules are loaded

Answer:

To find out what Linux kernel modules are loaded:

#  lsmod

Module                  Size  Used by
ipt_REJECT              3584  1
ipt_LOG                 6404  1
xt_limit                3236  2
xt_tcpudp               3616  10
xt_state                2432  6
ipt_addrtype            2912  4
ip6_tables             22576  0
nf_nat_irc              2688  0
nf_conntrack_irc        6552  1 nf_nat_irc
nf_nat_ftp              3584  0
nf_nat                 22164  2 nf_nat_irc,nf_nat_ftp
nf_conntrack_ipv4      16376  8 nf_nat
nf_defrag_ipv4          2400  1 nf_conntrack_ipv4
nf_conntrack_ftp        9016  1 nf_nat_ftp
...

To find out more information for a specific module

#  modinfo ip6_tables
filename:       /lib/modules/2.6.31-14-server/kernel/net/ipv6/netfilter/ip6_tables.ko
description:    IPv6 packet filter
author:         Netfilter Core Team 
license:        GPL
srcversion:     17E938A990111BB4A2F854B
depends:        x_tables
vermagic:       2.6.31-14-server SMP mod_unload modversions