Linux Advanced Notes


Get more deep into Linux administration.

Network Hacks


# Get default gateway
route -n get default # macOS
netstat -nr


# Writing ARP table (apt install -y net-tools)
arp -s 00:8b:8a:4c:25:1f

# ARP Spoofing (apt install -y dsniff ssldump)
arpspoof -i wls1 -t
# 0:22:fa:7a:3e:98 8c:f5:a3:81:44:0 0806 42: arp reply is-at 0:22:fa:7a:3e:98

MAC Address Spoofing

# Generate a fake one
MAC=`openssl rand -hex 6 | sed 's/\(..\)/\1:/g; s/.$//'`

# Set the fake MAC address to an interface
sudo ifconfig en0 ether $MAC

Scan hosts in the network

ping -c3 $BST | grep 'bytes from' | awk '{print $4}' | sed 's/://g' | sort -u > /tmp/hosts

nmap -iL /tmp/hosts

Network Interfaces

cat /proc/net/fib_trie  # interfaces and ip address
cat /proc/net/route     # routing

# And a lot of things in /proc/net
# --------------------------------
# anycast6      icmp6          ip_tables_matches  packet     rt_cache      udp
# arp           if_inet6       ip_tables_names    protocols  snmp          udp6
# connector     igmp           ip_tables_targets  psched     snmp6         udplite
# dev           igmp6          ipv6_route         ptype      sockstat      udplite6
# dev_mcast     ip6_flowlabel  mcfilter           raw        sockstat6     unix
# dev_snmp6/    ip6_mr_cache   mcfilter6          raw6       softnet_stat  wireless
# fib_trie      ip6_mr_vif     netfilter/         route      stat/         xfrm_stat
# fib_triestat  ip_mr_cache    netlink            rt6_stats  tcp
# icmp          ip_mr_vif      netstat            rt_acct    tcp6

What if there is only sh

Using sh without any other command

# cat < file
while read s; do echo "$s"; done < file

# cat > file
while read s; do echo "$s"; done > file

# ls -a
echo * .*