This script consolidates your "~/.ssh/known_hosts" file. All the aliases and internal/external IP addresses for a node will be merged into one line of the file.

ssh-known-hosts-optimize

#!/usr/bin/python
import os
import sys
import csv

home = os.getenv("HOME")
known_hosts_path = home+'/.ssh/known_hosts'
known_hosts_optimized_path = home+'/.ssh/known_hosts_optimized'
d = {}
csvfile = open(known_hosts_path, 'r')
khr = csv.reader(csvfile, delimiter=' ')
str_known_hosts_optimized = ""
optimization_count = 0
line_count = 0
for row in khr:
	line_count+=1
	key = row[2]
	hosts = row[0]
	method = row[1]
	if key in d:
		d[key]['hosts'] += "," + hosts
		optimization_count+=1
	else:
		d[key] = {'method':method, 'hosts': hosts}
for k in d:
	str_known_hosts_optimized += d[k]['hosts'] + " " + d[k]['method'] + " " + k + "\n"

if optimization_count > 0:
	optimizedcsvfile = open(known_hosts_optimized_path, "w")
	optimizedcsvfile.write(str_known_hosts_optimized)
	optimizedcsvfile.close()

	print "File \"%s\" has been optimized.\nDo you wish to overwrite it with optimized version? (y/n): " % (known_hosts_path), 
	response = sys.stdin.readline()
	if response.lower().find("y") >= 0:
		os.rename(known_hosts_optimized_path, known_hosts_path)
		print "Optimization complete.",
	else:
		print "Optimized file written to: \"%s\"." % known_hosts_optimized_path,
	print " (reduced from %d lines to %d lines)" % (line_count, line_count-optimization_count)
else:
	print "Your known_hosts file is already optimized. No action required."