125 commands · 7 cheat sheets · Linux

Networking and Connectivity master quick reference

Browse 125 commands from 7 focused cheat sheets on page 1 of 1. Each example opens its matching detailed section.

Networking and Connectivity · 14 commands

curl and HTTP Debugging Cheat Sheet

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UseSyntaxExamples
Include response headerscurl --include https://example.com/healthView examples
Request headers onlycurl --head https://example.com/assetView examples
Trace protocol exchangecurl --verbose https://example.com/healthView examples
Follow redirectscurl --location --max-redirs 5 https://example.com/oldView examples
Fail on HTTP errorscurl --fail-with-body https://example.com/apiView examples
Print status metadatacurl --silent --output /dev/null --write-out \ '%{http_code}\n' https://example.com/View examples
Send JSONcurl --json @payload.json https://api.example.com/itemsView examples
Add a headercurl --header 'Accept: application/json' \ https://api.example.com/itemsView examples
Upload a file bodycurl --upload-file ./artifact.bin \ https://upload.example.com/artifact.binView examples
Bound timecurl --connect-timeout 5 --max-time 30 \ https://example.com/View examples
Retry transient failurescurl --retry 3 --retry-all-errors --max-time 30 \ https://example.com/View examples
Save to an exact pathcurl --fail --output ./artifact.tar.gz \ https://example.com/artifact.tar.gzView examples
Use an explicit CA bundlecurl --cacert ./ca.pem https://internal.example/View examples
Measure phasescurl --output /dev/null --write-out \ 'dns=%{time_namelookup} connect=%{time_connect} total=%{time_total}\n' \ https://example.com/View examples

Networking and Connectivity · 18 commands

iproute2 Routing and Traffic Control Cheat Sheet

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Show concise addressesip -brief address showView examples
Export routes as JSONip -json route show table allView examples
Resolve an IPv4 pathip route get 203.0.113.10 from 192.0.2.20View examples
Resolve an IPv6 pathip -6 route get 2001:db8:2::10 from 2001:db8:1::20View examples
Show the main tableip route show table mainView examples
Replace a route idempotentlysudo ip route replace 198.51.100.0/24 via 192.0.2.1 dev \ eth0 metric 100View examples
Delete an exact routesudo ip route del 198.51.100.0/24 via 192.0.2.1 dev eth0 \ metric 100View examples
Show policy rulesip -details rule showView examples
Add a source policysudo ip rule add priority 1000 from 192.0.2.0/24 table \ 100View examples
Add a policy-table defaultsudo ip route replace default via 192.0.2.1 dev eth0 \ table 100View examples
Monitor network changesip monitor link address route ruleView examples
Show neighbor stateip -details neighbor show dev eth0View examples
Flush failed neighborssudo ip neighbor flush dev eth0 nud failedView examples
Show queue disciplinestc -s qdisc show dev eth0View examples
Install fq_codel root qdiscsudo tc qdisc replace dev eth0 root fq_codelView examples
Add lab delay and losssudo tc qdisc replace dev veth-test root netem delay \ 50ms loss 0.1%View examples
Remove a root qdiscsudo tc qdisc del dev veth-test rootView examples
Show iproute2 versionip -VersionView examples

Networking and Connectivity · 20 commands

Linux DNS Resolution and Resolver Tools Cheat Sheet

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UseSyntaxExamples
Resolve through NSSgetent ahosts example.comView examples
Inspect hosts lookup ordergrep -E '^[[:space:]]*hosts:' /etc/nsswitch.confView examples
Identify resolv.conf ownerreadlink -f /etc/resolv.confView examples
Show resolver directivesgrep -E \ '^[[:space:]]*(nameserver|search|domain|options)[[:space:]]' \ /etc/resolv.confView examples
Query an A recorddig example.com A +noall +answerView examples
Query an AAAA recorddig example.com AAAA +noall +answerView examples
Query one DNS serverdig @192.0.2.53 example.com A +noall +answer +commentsView examples
Run a reverse lookupdig -x 192.0.2.25 +noall +answerView examples
Retry DNS over TCPdig +tcp @192.0.2.53 example.com AView examples
Trace delegationdig +trace www.example.comView examples
Show effective DNS policyresolvectl statusView examples
Query through systemd-resolvedresolvectl query example.comView examples
Inspect resolver statisticsresolvectl statisticsView examples
Bypass the local cacheresolvectl --cache=no query example.comView examples
Flush resolved cachessudo resolvectl flush-cachesView examples
Request DNSSEC recordsdig example.com A +dnssec +multiView examples
Show per-link domainsresolvectl domainView examples
Set transient split DNSsudo resolvectl domain tun0 '~corp.example'View examples
Set a per-link DNS serversudo resolvectl dns tun0 192.0.2.53View examples
Revert transient link DNSsudo resolvectl revert tun0View examples

Networking and Connectivity · 17 commands

Linux Network Diagnostics Cheat Sheet

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UseSyntaxExamples
Show interface addressesip -brief address showView examples
Inspect link countersip -s link show dev eth0View examples
Show routesip route showView examples
Resolve an outbound routeip route get 1.1.1.1View examples
Inspect neighborsip neighbor showView examples
Send a bounded pingping -c 4 example.comView examples
Test IPv6 reachabilityping -6 -c 4 example.comView examples
Show listening TCP socketsss -lntView examples
Show established TCP socketsss -nt state establishedView examples
Include owning processessudo ss -lntpView examples
Use system name resolutiongetent ahosts example.comView examples
Query an A recorddig example.com AView examples
Show concise DNS answersdig +short example.com AAAAView examples
Fetch response headerscurl -I https://example.com/View examples
Print an HTTP statuscurl -sS -o /dev/null -w '%{http_code}\n' \ https://example.com/View examples
Bound connection timecurl --connect-timeout 5 https://example.com/View examples
Trace a requestcurl -v --connect-timeout 5 https://example.com/View examples

Networking and Connectivity · 14 commands

Linux nftables Firewall Cheat Sheet

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List the rulesetsudo nft list rulesetView examples
Show rule handlessudo nft --handle list rulesetView examples
Back up active rulessudo nft list ruleset > ./nftables.backupView examples
Validate a filesudo nft --check --file ./nftables.confView examples
Load a batchsudo nft --file ./nftables.confView examples
Create an inet tablesudo nft add table inet filterView examples
Create an input base chainsudo nft \ 'add chain inet filter input { type filter hook input priority filter; policy drop; }'View examples
Allow established trafficsudo nft add rule inet filter input ct state \ established,related acceptView examples
Allow loopbacksudo nft add rule inet filter input iifname lo acceptView examples
Allow TCP servicesudo nft add rule inet filter input tcp dport 22 ct \ state new accept comment 'management SSH'View examples
Create an address setsudo nft \ 'add set inet filter admins { type ipv4_addr; flags interval; }'View examples
Count rule matchessudo nft add rule inet filter input tcp dport 443 \ counter acceptView examples
Monitor tracessudo nft monitor traceView examples
Monitor ruleset eventssudo nft monitor rulesetView examples

Networking and Connectivity · 20 commands

NetworkManager Wi-Fi and Connections Cheat Sheet

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UseSyntaxExamples
Show overall statusnmcli general statusView examples
List devicesnmcli device statusView examples
List active profilesnmcli connection show --activeView examples
Inspect a profilenmcli -f connection,ipv4,ipv6 connection show id \ 'Office Wi-Fi'View examples
List access pointsnmcli -f IN-USE,SSID,BSSID,CHAN,RATE,SIGNAL,SECURITY \ device wifi list ifname wlp2s0View examples
Request a rescannmcli device wifi rescan ifname wlp2s0View examples
Connect with a promptnmcli --ask device wifi connect 'Office Wi-Fi' ifname \ wlp2s0 name 'Office Wi-Fi'View examples
Activate using a secrets filenmcli connection up id 'Office Wi-Fi' ifname wlp2s0 \ passwd-file /run/user/1000/nm-secretsView examples
Activate by UUIDnmcli connection up uuid \ 3f4f1df0-a596-4ca4-94be-31d6c0674c5e ifname wlp2s0View examples
Deactivate a profilenmcli connection down uuid \ 3f4f1df0-a596-4ca4-94be-31d6c0674c5eView examples
Set autoconnect prioritysudo nmcli connection modify id 'Office Wi-Fi' \ connection.autoconnect yes \ connection.autoconnect-priority 20View examples
Configure static IPv4sudo nmcli connection modify id 'Office LAN' ipv4.method \ manual ipv4.addresses 192.0.2.20/24 ipv4.gateway \ 192.0.2.1View examples
Set profile DNSsudo nmcli connection modify id 'Office LAN' \ ipv4.ignore-auto-dns yes ipv4.dns \ '192.0.2.53 192.0.2.54'View examples
Add a profile routesudo nmcli connection modify id 'Office LAN' \ +ipv4.routes '198.51.100.0/24 192.0.2.1, 50'View examples
Reload profilessudo nmcli connection reloadView examples
Reapply compatible settingssudo nmcli device reapply wlp2s0View examples
Run under a checkpointsudo nmcli device checkpoint --timeout 60 wlp2s0 -- \ nmcli connection up id 'Office Wi-Fi'View examples
Monitor changesnmcli monitorView examples
Read service logsjournalctl -u NetworkManager.service --since today \ --no-pagerView examples
Show nmcli versionnmcli --versionView examples

Networking and Connectivity · 22 commands

WireGuard VPN Cheat Sheet

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UseSyntaxExamples
Show all interfacessudo wg showView examples
Show runtime configurationsudo wg showconf wg0View examples
List WireGuard interfaceswg show interfacesView examples
Generate a private keyumask 077; wg genkey > privatekeyView examples
Derive a public keywg pubkey < privatekey > publickeyView examples
Generate a preshared keyumask 077; wg genpsk > presharedkeyView examples
Create an interfacesudo ip link add dev wg0 type wireguardView examples
Load configurationsudo wg setconf wg0 /etc/wireguard/wg0.confView examples
Assign a tunnel addresssudo ip address add 10.20.0.1/24 dev wg0View examples
Bring the link upsudo ip link set up dev wg0View examples
Start with wg-quicksudo wg-quick up wg0View examples
Stop with wg-quicksudo wg-quick down wg0View examples
Save runtime statesudo wg-quick save wg0View examples
Synchronize peer configsudo wg syncconf wg0 /run/wireguard/wg0.stripped.confView examples
Strip wg-quick fieldssudo wg-quick strip wg0View examples
Check route selectionip route get 10.20.0.2View examples
Show handshake epochssudo wg show wg0 latest-handshakesView examples
Show transfer counterssudo wg show wg0 transferView examples
Show learned endpointssudo wg show wg0 endpointsView examples
Update one peersudo wg set wg0 peer PUBLIC_KEY allowed-ips 10.20.0.2/32 \ endpoint vpn.example.net:51820View examples
Remove a peersudo wg set wg0 peer PUBLIC_KEY removeView examples
Show tools versionwg --versionView examples
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