resolv.conf and gnupg2

Tue Aug 9 06:17:32 GMT 2022

I've been running with /etc/resolv.conf for a few years now, generated 
from the ISP info from ipconfig and lists of public DNS servers and 
suffixes.
The attached postinstall script 0p_l_etc_resolv_conf.dash generates a 
new resolv.conf and replaces the current if different every update.
It is also run at cron startup and that covers system startup.
The AWK script collects names and addresses from ipconfig ouput and adds 
lists of public DNS servers and public suffixes in the proper order.
How this works with other ISPs or in other network environments is not 
anything I ever thought of testing externally.
Feel feel to try it and change it if curious or interested.
I'be been shuffling my keyservers since keyserver public key certificate 
poisoning started; currently I have the following formerly "safe" 
servers configured in ~/gnupg/dirmngr.conf:
#keyserver hkp://pool.sks-keyservers.net
#keyserver hkps://hkps.pool.sks-keyservers.net
#keyserver hkp://keys.gnupg.net
keyserver hkps://keyserver.ubuntu.com
keyserver hkps://keys.openpgp.org
keyserver hkp://pgp.mit.edu
keyserver hkp://pgp.surf.nl
also in ~/.gnupg/gpg.conf:
#keyserver hkp://pool.sks-keyservers.net
#keyserver hkps://hkps.pool.sks-keyservers.net
#keyserver hkp://keys.gnupg.net
keyserver hkp://keyserver.ubuntu.com
keyserver hkps://keys.openpgp.org
keyserver hkp://pgp.mit.edu
keyserver hkp://pgp.surf.nl
#keyserver mailto:pgp-public-keys@keys.nl.pgp.net
#keyserver ldap://keyserver.pgp.com
I've also installed US DoD (for USNO data) and LE root CA certs and sub 
CA certs to extend access where not provided in Windows and/or Cygwin.
-- 
Take care. Thanks, Brian Inglis, Calgary, Alberta, Canada
This email may be disturbing to some readers as it contains
too much technical detail. Reader discretion is advised.
[Data in binary units and prefixes, physical quantities in SI.]
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#!/bin/dash
# 0p_l_etc_resolv_conf.dash - update /etc/resolv.conf if changed
r=resolv
cr=/usr/local/bin/cyg-$r.awk
run=/var/run/${r}conf
rrc=$run/$r.conf
SYSCONFDIR=${SYSCONFDIR:-/etc}
conf=$SYSCONFDIR/$r.conf
/bin/mkdir -pv		-- $run/		&& \
ip=$(/usr/bin/which	-- ipconfig)		&& \
tmp=$(/bin/mktemp -t	-- .XXXXXXXX.)		&& \
$ip /all | $cr	 > $tmp				&& \
[ -s $tmp ]					&& \
[ -w $rrc ]	|| : > $rrc
if ! /usr/bin/cmp -s	-- $tmp $rrc; then
 /bin/cp -fv		-- $tmp $rrc
 /bin/ln -frsTv	-- $rrc $conf
fi
/bin/rm -f		-- $tmp
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#!/usr/bin/awk -f
# cyg-resolv.awk - create Cygwin resolv.conf from Windows ipconfig /all output
function nextaddr( addr, name, ns, nameserveraddr, nameserverhostname	,private,n) {
 if (DEBUG) print addr, name, ns > DEBUG
 # private subnets
 private = (addr ~ p10 || addr ~ p172 || addr ~ p192)
 # default name
 if (private && !name) { name = "private" }
 # private subnets come first if unoccupied
 if (private && !(0 in nameserveraddr)) {
	n = 0
 } else {
	n = ++ns
 }
 if (addr) { nameserveraddr[n]	= addr }
 if (name) { nameserverhostname[n] = name }
 if (DEBUG) print addr, name, ns > DEBUG
 return ns
}
function addrs( NS, nameserveraddr, ns, c, l) {
# $ getent ahostsv4 $NS
# 1.0.0.1 STREAM one.one.one.one
# 1.0.0.1 DGRAM one.one.one.one
# 1.1.1.1 STREAM
# 1.1.1.1 DGRAM
# 149.112.112.112 0 dns.quad9.net
# 9.9.9.9 0
# 208.67.220.220 0 resolver2.opendns.com
# 208.67.222.222 0 resolver1.opendns.com
# 8.8.4.4 0 google-public-dns-b.google.com
# 8.8.8.8 0 google-public-dns-a.google.com
# 149.112.122.20 0 CAshieldProtected 
# 149.112.121.20 0
 l = 0
 c = "/usr/bin/getent ahostsv4 " NS
 while ((c | getline) > 0) {
	if (1ドル != l) {
	 ns = nextaddr( 1,ドル 3,ドル ns, nameserveraddr, nameserverhostname)
	}
	l = 1ドル
 }
 return ns
}
BEGIN {
# private subnets
 # digit patterns: .[0[0]]0-255, .[0]16-31
 d0_255	= "(.(0{0,2}[0-9]|0{0,1}[1-9][0-9]|1[0-9][0-9]|2([0-4][0-9]|5[0-5])))"
 d16_31	= ".0?(1[6-9]|2[0-9]|3[01])"
 # 10.0.0.0-.255.255.255
 p10		= "^10" d0_255 "{3}$"
 # 172.16.0.0-.31.255.255
 p172	= "^172" d16_31 d0_255 "{2}$"
 # 192.168.0.0-.255.255
 p192	= "^192.168" d0_255 "{2}$"
# public name servers
# CIRA Canadian Shield Protected+malware+phishing
 NS = "dns.quad9.net. one.one.one.one. "				\
	 "resolver2.opendns.com. resolver1.opendns.com. "		\
	 "google-public-dns-b.google.com. google-public-dns-a.google.com. " \
	 "CAshieldProtected"
 SUF = "ca. org. com. net."
 CFHD = "# /etc/resolv.conf"
 CFHD = CFHD " - Internet Domain Name System resolver configuration file"
 CDS = "# domain suffix"
 CSSL = "# suffix search list"
}
/\r/				{ sub( /\r/, "", $NF) }	# trim \r
# collect DNS domain suffixes
/D[Nn][Ss]\sSuffix[^:]*:\s\S/	{
 last = $NF
 if (last ~ /\./ && last !~ /\.$/)	last = last ".";	# add root dot
 if (!(last in domain)) {
	domain[last] = last
	domains = domains " " last
 }
 while (last ~ /\..+\..+/) {	# strip labels if more than two for domain
	sub(/^[^.]+./, "", last)
	if (last ~ /\./ && last !~ /\.$/)	last = last "."; # add root dot
	if (!(last in domain)) {
	 domain[last] = last
	 domains = domains " " last
	}
 }
}
# collect DNS search suffixes
/Search\sList[^:]*:\s\S/	{
 for (d in domain) {
	if (!(d in search))	search[d] = d
	if (d ~ /shaw[^.]+./) {
	 last = "shaw.ca."
	 if (!(last in search)) {
		search[last] = last
		domains = domains " " last
	 }
	}
 }
 last = $NF
 if (last ~ /\./ && last !~ /\.$/)	last = last ".";	# add root dot
 if (!(last in search)) {
	search[last] = last
	domains = domains " " last
 }
 while (last ~ /\..+\..+/) {	# strip labels if more than two for domain
	sub(/^[^.]+./, "", last)
	if (last ~ /\./ && last !~ /\.$/)	last = last "."; # add root dot
	if (!(last in search)) {
	 search[last] = last
	 domains = domains " " last
	}
 }
 ns = split( SUF, sa)
 for (s = 1; s <= ns; ++s) {
	last = sa[s]
	if (last ~ /\./ && last !~ /\.$/)	last = last "."; # add root dot
	if (!(last in search)) {
	 search[last] = last
	 domains = domains " " last
	}
 }
}
# collect DNS server IP V4 addresses
/DNS\sServers[^:]*:\s\S/	{ dns = 1 }		# start - enable
dns && $NF ~ /^([0-9A-Fa-f]{0,4}:){1,7}[0-9A-Fa-f]{0,4}$/ { next } # skip IP V6
dns && $NF ~ /^([0-9]{1,3}\.){3}[0-9]{1,3}$/	{		# collect IP V4
 ns = nextaddr( $NF, last, ns, nameserveraddr, nameserverhostname)
 last = ""
}
dns && $NF !~ /^([0-9A-Fa-f]{0,4}:){1,7}[0-9A-Fa-f]{0,4}$/ && \
	$NF !~ /^([0-9]{1,3}\.){3}[0-9]{1,3}$/	{ dns = 0 }	# non-IP disable
# output unique resolv.conf entries
END {
 print CFHD
 ns = addrs( NS, nameserveraddr, ns)
 for (n = 0; n <= ns; ++n)	{
	if (n in nameserverhostname && nameserverhostname[n]) {
	 print "#", nameserverhostname[n]
	}
	if (n in nameserveraddr && nameserveraddr[n]) {
	 print "nameserver", nameserveraddr[n]
	}
 }
 print CDS
 for (d in domain)		{ print "domain " d }
 print CSSL
 if (domains)	print "search" domains
}
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# /etc/resolv.conf - Internet Domain Name System resolver configuration file
# shawcable.net.
nameserver 64.59.135.148
nameserver 64.59.128.114
# dns.quad9.net
nameserver 9.9.9.9
nameserver 149.112.112.112
# one.one.one.one
nameserver 1.1.1.1
nameserver 1.0.0.1
# resolver2.opendns.com
nameserver 208.67.220.220
# resolver1.opendns.com
nameserver 208.67.222.222
# google-public-dns-b.google.com
nameserver 8.8.4.4
# google-public-dns-a.google.com
nameserver 8.8.8.8
# CAshieldProtected
nameserver 149.112.121.20
nameserver 149.112.122.20
# domain suffix
domain shawcable.net.
domain cg.shawcable.net.
# suffix search list
search cg.shawcable.net. shawcable.net. shaw.ca. ca. org. com. net.