Routers and DNS - sgml/signature GitHub Wiki

• ping the IP address of your current DNS with an explicit MTU
• test with a packet size of 50 less than the MTU
• repeat with a lower MTU if there is packet loss
• keep repeating, lowering the MTU by 50 each time until there is no packet loss
• save the MTU on the router and/or modem
• ping example.com with the new MTU
• repeat as before until there is no packet loss
• trace the route to each DNS server based on these lists:
  • https://dnschecker.org/dns/United-States-of-America/Comcast
  • https://dnsmap.io/articles/most-popular-dns-servers
  • https://dnschecker.org/public-dns/us
• Set the DNS servers to the ones with the lowest number of hops
• Manually set the DNS server on the client to fail fast
• Reset TCP/IP
• Use Multiples of 576: 576, 864, 1152, 1326, 1500

tcpdump -i eth0 -l | awk '{print strftime("[%Y-%m-%d %H:%M:%S]"), $0}' | grep -v "ARP" > packet_log.txt

• Set the primary and secondary to the closest DNS server based on geolocation
• Reverse the primary and secondary order on the DHCP server settings versus the main router settings

• Check the client device itself; if it is using manual DNS IP address entries, delete them; switch to manual to avoid intermittent DNS hopping
• Check the DNS IP addresses via ping; change them at least once every few years

• Export all settings
• Do a factory reset periodically, then import the old settings
• Use traceroute and ping regularly, and never expect one setting to rule them all

• Use 5Ghz to extend 2.4Ghz since 5Ghz has more range
• Use an older router as an access point hub for all wired connections
• DO NOT override DHCP servers on a device by device basis
• Fix DHCP issues by doing a factory reset, rather than turning DHCP off

• Find the endpoint URL
  • Google: lens.meet.l.google.com
• Run ping and traceroute
• Update DNS to reduce the number of hops to 12 or less

• https://support.google.com/a/answer/7582554?
• https://support.google.com/a/answer/1279090?

• https://support.zoom.com/hc/en/article?id=zm_kb&sysparm_article=KB0060548
• https://support.zoom.com/hc/en/article?id=zm_kb&sysparm_article=KB0063568

• Cut RTS in half 2346 / 2 = 1173, then retest
• Cut RTS in a third 2346 / 3 = 782, then retest
• If download speed is unaffected, reset to 2346

• Set Beacon to the min, then retest
• Set Beacon to the max, then retest
• If download speed is unaffected, then reset to the default

• Set DTIM to double 1 * 2 = 2, then retest
• Set DTIM to quadruple 1 * 4 = 4, then retest
• If download speed is unaffected, reset to 1

ping -c 4 -M do -s 1500 208.201.224.33

ping -c 4 -M do -s 1400 208.201.224.33

ping -c 4 -M do -s 1300 208.201.224.33

sudo ip link set dev wlp1s0 mtu 1200

ipconfig /flushdns

ipconfig /registerdns

ipconfig /release

ipconfig /renew

netsh int ip reset

netsh winsock reset c:\winsocklog.txt

• https://www.fortinet.com/resources/cyberglossary/wardriving
• https://github.blog/security/application-security/localhost-dangers-cors-and-dns-rebinding/
• https://www.darkreading.com/cyberattacks-data-breaches/wardrivers-can-still-crack-70-of-wifi-passwords

• Network Time Protocol
• https://www.speedguide.net/speedtest/results.php?test=1724247115
• https://www.speedguide.net/speedtest/results.php?test=1712982927
• https://wiki.dd-wrt.com/wiki/index.php/Advanced_wireless_settings
• https://www.ibm.com/blog/using-dig-trace/
• https://docs.oracle.com/en-us/iaas/Content/DNS/Tasks/testingdnsusingdig.htm
• https://www.baeldung.com/linux/dns-speed-test
• https://netbeez.net/blog/testing-packet-loss/
• https://www.xfinity.com/support/repair/internet
• https://speedtest.xfinity.com/
• https://webrtc.github.io/samples/
• https://webrtc.github.io/test-pages/

• https://www.tp-link.com/us/support/faq/2584/
• https://www.tp-link.com/us/support/faq/1482/
• https://www.tp-link.com/us/support/download/archer-ax50/#FAQs

• https://www.baeldung.com/linux/maximum-transmission-unit-change-size
• https://netbeez.net/blog/network-performance-analysis/
• https://netbeez.net/blog/linux-network-path-analysis-mtr/

• https://humanwhocodes.com/blog/2024/05/someone-temporarily-took-over-subdomain/
• https://www.ibm.com/topics/primary-dns
• https://www.catchpoint.com/dns-monitoring/slow-dns
• https://public-dns.info/

• https://www.makeuseof.com/what-is-mac-binding-how-does-it-work/
• https://www.tp-link.com/us/support/faq/170/

• https://blog.apnic.net/tag/dhcp/

• https://www.tp-link.com/us/home-networking/wifi-router/archer-ax50/

https://www.xfinity.com/support/status

https://www.xfinity.com/support/statusmap

https://documentation.extremenetworks.com/wireless/UG/Wireless/User_Guide/r_radio-properties-advanced.shtml

http://ftp.hp.com/pub/networking/software/06-C03-RadioPortConfig.pdf

https://techcommunity.microsoft.com/t5/windows-insider-program/system-reports-no-internet-despite-having-active-connection/m-p/687560/page/2

https://www.guidetotcpip.com/wp-content/uploads/files/Appendices/tcpip5e_CommandLineIPUtils.pdf

https://techwiser.com/how-to-reset-tcp/

https://www.dslreports.com/forum/r32534903-DSL-I-solved-my-high-latency-problem-created-by-frontier

http://www.linux-magazine.com/Issues/2014/161/Security-and-SOHO-Routers

http://screenshots.portforward.com/

https://en.wikipedia.org/wiki/Uniregistry

https://www.cisco.com/c/en/us/td/docs/solutions/Enterprise/Mobility/emob41dg/emob41dg-wrapper/ch3_WLAN.pdf

http://ptgmedia.pearsoncmg.com/images/9780789753342/samplepages/9780789753342.pdf

http://www.gadgetvictims.com/2016/10/who-else-is-watching-your-ip-cameras.html

https://blog.cloudflare.com/understanding-the-prevalence-of-web-traffic-interception/

https://blog.cloudflare.com/introducing-strict-ssl-protecting-against-a-man-in-the-middle-attack-on-origin-traffic/

https://www.sunsetlearning.com/wp-content/uploads/2014/01/The-Next-Generation-of-Cisco-SSL-VPN-Solution-from-Sunset-Learning.pdf

https://docs.microsoft.com/en-us/previous-versions/tn-archive/dd261764(v=technet.10)

https://www.cisco.com/c/en/us/td/docs/security/vpn_client/anyconnect/anyconnect40/administration/guide/b_AnyConnect_Administrator_Guide_4-0/configure-vpn.html

https://blog.webernetz.net/cisco-anyconnect-ipv6-access-through-ipv4-vpn-tunnel/

https://thebestvpn.com/chrome-extension-vpn-dns-leaks/

https://www.linksys.com/sg/support-article?articleNum=142456

https://superuser.com/questions/936062/expanding-wireless-coverage-what-are-the-differences-between-lan-to-lan-and-lan

http://www.tcpipguide.com/content.htm

http://www.l-com.com/content/Article.aspx?Type=L&ID=467

https://www.mathworks.com/help/wlan/gs/what-is-wlan.html

http://www.dtic.mil/dtic/tr/fulltext/u2/a420632.pdf

http://www.dtic.mil/dtic/tr/fulltext/u2/a497761.pdf

http://www.au.af.mil/au/awc/awcgate/cst/bh_peacock.pdf

https://ws680.nist.gov/publication/get_pdf.cfm?pub_id=33178

http://www.dtic.mil/dtic/tr/fulltext/u2/a480069.pdf

https://share-ng.sandia.gov/news/resources/releases/2006/images/wireless-fingerprinting.pdf

https://www.cisco.com/c/en/us/support/docs/ip/dynamic-address-allocation-resolution/22920-dhcp-ser.html

https://www.debian.org/doc/manuals/debian-reference/ch05

http://www.ni.com/white-paper/12558/en/

https://superuser.com/questions/876301/cascading-routers-lan-to-wan-and-dns

https://superuser.com/questions/978667/static-dns-when-connected-to-vpn-loses-internet-connection

https://superuser.com/questions/1288878/dns-server-unreachable-from-one-client

https://docs.microsoft.com/en-us/previous-versions/windows/it-pro/windows-server-2012-R2-and-2012/dn800669(v=ws.11)

https://technet.microsoft.com/pt-pt/library/cc772774(v=ws.10).aspx

https://tools.ietf.org/html/rfc1034

https://tools.ietf.org/html/rfc2136

http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.479.9416&rep=rep1&type=pdf

https://support.apple.com/en-us/HT202944

https://openconnect.netflix.com/en/network-configuration/

https://docs.aws.amazon.com/workspaces/latest/adminguide/workspaces-port-requirements.html

https://corporate.comcast.com/images/Comcast_Innovation_Fund_-_2016_Annual_Report_PKlPHJY.pdf

https://business.comcast.com/help-and-support/internet/comcast-business-ip-gateway-static-firewall/

https://www.xfinity.com/support/articles/run-traceroute-command

https://support.xbox.com/en-US/xbox-360/networking/network-ports-used-xbox-live

https://partnerhelp.netflixstudios.com/hc/en-us/articles/115000257627-What-are-Netflix-s-Aspera-IP-Addresses-and-Port-Ranges-

https://frontier.com/helpcenter/categories/categories/internet/get-rid-of-problems#/collapse3

http://shouldiblockicmp.com/ 33001

https://www.getcujo.com/wp-content/uploads/2016/04/CUJO_Manual_Instructions.pdf

http://www.aptivate.org/uploads/filer_public/e6/91/e69134af-8c33-4d0c-8b80-aa5674fe38cb/bwmo-print.pdf

https://www.tp-link.com/us/support/faq/

https://community.spiceworks.com/how_to/1014-how-to-convert-a-wireless-router-into-an-access-point

https://support.google.com/wifi/answer/6277579

https://support.apple.com/en-au/HT202068

https://www.freebsd.org/doc/en_US.ISO8859-1/books/handbook/network-wireless.html

https://www.cisco.com/c/en/us/support/docs/wireless-mobility/80211/200527-Fundamentals-of-802-11-Wireless-Sniffing.html

https://tools.ietf.org/id/draft-perkins-intarea-multicast-ieee802-03.html

https://tools.ietf.org/id/draft-ietf-mboned-ieee802-mcast-problems-01.html

https://dri.es/files/wlan-faq.html

https://link.springer.com/content/pdf/bbm%3A978-1-4020-5397-9%2F1.pdf

http://ftp1.digi.com/support/documentation/0190170_b.pdf

https://mentor.ieee.org/802.15/dcn/12/15-12-0600-00-0l2r-l2r-november-2012-tutorial.pdf

https://arxiv.org/pdf/1601.00028.pdf

http://www.nyu.edu/classes/jcf/CSCI-GA.2262-001_fa13/slides/session5/WirelessAndMobileNetworks.pdf

https://web.stanford.edu/dept/its/support/techtraining/techbriefing-media/Building-Home-Network-72409.pdf

https://www.methodist.edu/sites/default/files/ctools/CompTIA_Network_N10-005.pdf

http://ridl.cfd.rit.edu/products/manuals/IPCam/IP%20CAM%20%20UM.pdf

https://www.redbooks.ibm.com/redbooks/pdfs/gg243376.pdf

https://docs.oracle.com/cd/E52521_01/doc.420/910-5411-001_rev_c.pdf

https://ruckus-www.s3.amazonaws.com/pdf/wp/wp-how-interworking-works.pdf

http://www.sanog.org/resources/sanog17/sanog17-wifi-wimax-tanim.pdf

https://www.silabs.com/documents/login/presentations/WiFi-technology.pdf

https://www.gsma.com/newsroom/wp-content/uploads/TS.22_v5.0.pdf

https://www.arris.com/globalassets/resources/white-papers/arris_quest_4k_video_over_wi-fi_wp.pdf

https://www.savvius.com/networking-glossary/wireless_lan_overview/wlan_packets/

http://www.practicallynetworked.com/networking/fixing_double_nat.htm

https://devblogs.microsoft.com/scripting/use-powershell-for-network-host-and-port-discovery-sweeps/

https://superuser.com/questions/45687/how-can-i-ping-a-range-of-ip-addresses-simultaneously

https://serverfault.com/questions/153776/nmap-find-all-alive-hostnames-and-ips-in-lan

https://superuser.com/questions/805621/test-network-ports-faster-with-powershell

https://davidhamann.de/2017/09/27/vpn-connect-to-server-same-subnet/

https://searchnetworking.techtarget.com/tip/Prevent-IP-address-conflicts-on-your-wireless-network-by-managing-DHCP-scopes

• https://portforward.com/nat-types/
• https://www.mbreviews.com/how-to-change-nat-type/
• https://support.xbox.com/en-US/help/hardware-network/connect-network/xbox-360-nat-error
• https://support.xbox.com/en-US/help/hardware-network/connect-network/xbox-one-nat-error
• https://openwrt.org/docs/guide-user/network/wan/dmz-based-bridge-mode
• https://openwrt.org/docs/guide-user/network/switch_router_gateway_and_nat

• https://www.dslreports.com/forum/r31600056-Vantage-Help-with-Arris-nvg443b-bridge-mode?search=%22Cascaded%20Router%22%20443b
• https://www.cisco.com/c/en/us/support/docs/voice-unified-communications/spa8000-8-port-ip-telephony-gateway/108670-pqa-108670.html
• https://nerdbacon.com/router-to-wireless-bridge/
• https://nerdbacon.com/convert-router-to-bridge-v4/
• https://www.tp-link.com/us/support/faq/717/
• https://www.cnet.com/home/internet/how-to-turn-an-old-wi-fi-router-into-an-access-point/
• https://lifehacker.com/how-to-extend-your-wi-fi-network-with-an-old-router-915783308

• https://ipinstructor.com/working-ip-addresses-for-popular-websites/

https://support.ooma.com/home/advanced-connections-and-service-ports/

https://help.webex.com/en-us/b2exve/Port-Reference-for-Cisco-Webex-Calling-Value-Added-Resellers

https://help.webex.com/en-us/WBX264/How-Do-I-Allow-Webex-Meetings-Traffic-on-My-Network

https://d1nmyq4gcgsfi5.cloudfront.net/fileMedia/4588769e-3624-4778-9aa6-9456e8336a2f/URL%20API%20WBS%2027%20Ref%20Guide.pdf

https://www.dslreports.com/forum/r32629626-Price-I-just-don-t-get-it~start=30

http://www.dslreports.com/faq/15643

https://www.xfinity.com/networkmanagement

• https://gilks.github.io/post/cisco-hostscan-bypass/

• https://weworkremotely.com/the-remote-show-podcast/
• https://tunein.com/podcasts/Technology-Podcasts/Codeish-p1214694/
• https://sharkbytes.transistor.fm/

• https://www.computerhope.com/jargon/acronyms.htm
• https://wiki.dd-wrt.com/wiki/index.php/Glossary