This file is indexed.

/etc/ufw/sysctl.conf is in ufw 0.34~rc-0ubuntu2.

This file is owned by root:root, with mode 0o644.

The actual contents of the file can be viewed below.

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#
# Configuration file for setting network variables. Please note these settings
# override /etc/sysctl.conf. If you prefer to use /etc/sysctl.conf, please
# adjust IPT_SYSCTL in /etc/default/ufw.
#

# Uncomment this to allow this host to route packets between interfaces
#net/ipv4/ip_forward=1
#net/ipv6/conf/default/forwarding=1
#net/ipv6/conf/all/forwarding=1

# Turn on Source Address Verification in all interfaces to prevent some
# spoofing attacks
net/ipv4/conf/default/rp_filter=1
net/ipv4/conf/all/rp_filter=1

# Do not accept IP source route packets (we are not a router)
net/ipv4/conf/default/accept_source_route=0
net/ipv4/conf/all/accept_source_route=0
net/ipv6/conf/default/accept_source_route=0
net/ipv6/conf/all/accept_source_route=0

# Disable ICMP redirects. ICMP redirects are rarely used but can be used in
# MITM (man-in-the-middle) attacks. Disabling ICMP may disrupt legitimate
# traffic to those sites.
net/ipv4/conf/default/accept_redirects=0
net/ipv4/conf/all/accept_redirects=0
net/ipv6/conf/default/accept_redirects=0
net/ipv6/conf/all/accept_redirects=0

# Ignore bogus ICMP errors
net/ipv4/icmp_echo_ignore_broadcasts=1
net/ipv4/icmp_ignore_bogus_error_responses=1
net/ipv4/icmp_echo_ignore_all=0

# Don't log Martian Packets (impossible packets)
net/ipv4/conf/default/log_martians=0
net/ipv4/conf/all/log_martians=0

# Change to '1' to enable TCP/IP SYN cookies This disables TCP Window Scaling
# (http://lkml.org/lkml/2008/2/5/167)
net/ipv4/tcp_syncookies=0

#net/ipv4/tcp_fin_timeout=30
#net/ipv4/tcp_keepalive_intvl=1800

# normally allowing tcp_sack is ok, but if going through OpenBSD 3.8 RELEASE or
# earlier pf firewall, should set this to 0
net/ipv4/tcp_sack=1

# Uncomment this to turn off ipv6 autoconfiguration
#net/ipv6/conf/default/autoconf=0
#net/ipv6/conf/all/autoconf=0

# Uncomment this to enable ipv6 privacy addressing
#net/ipv6/conf/default/use_tempaddr=2
#net/ipv6/conf/all/use_tempaddr=2