Linux Utils
Ping
I have used ping often but never to an extend that I could understand the complete range of options and power available at hand.
ping – send ICMP ECHO_REQUEST to network hosts
from – man page of ping
ICMP Packet details
An IP header without options is 20 bytes. An ICMP ECHO_REQUEST packet contains an additional 8 bytes worth of ICMP header followed by an arbitrary amount of data.
Examples
ping hostname #www.samarthya.meping www.samarthya.me
PING samarthya.me (148.72.168.185) 56(84) bytes of data.
64 bytes from server4.hostsoch.in (148.72.168.185): icmp_seq=1 ttl=53 time=251 ms
64 bytes from server4.hostsoch.in (148.72.168.185): icmp_seq=8 ttl=53 time=252 ms
^C
--- samarthya.me ping statistics ---
2 packets transmitted, 2 received, 0% packet loss, time 2007ms
rtt min/avg/max/mdev = 250.972/251.358/252.325/0.657 msping ip #148.32.168.185ping 148.72.168.185
PING 148.72.168.185 (148.72.168.185) 56(84) bytes of data.
64 bytes from 148.72.168.185: icmp_seq=1 ttl=53 time=251 ms
64 bytes from 148.72.168.185: icmp_seq=2 ttl=53 time=251 ms
64 bytes from 148.72.168.185: icmp_seq=3 ttl=53 time=251 ms
^C
--- 148.72.168.185 ping statistics ---
3 packets transmitted, 3 received, 0% packet loss, time 2002ms
rtt min/avg/max/mdev = 251.039/251.231/251.438/0.601 msOptions available that I can use are
ping [-aAbBdDfhLnOqrRUvV46] [-c count] [-F flowlabel] [-i interval] [-I interface] [-l preload] [-m mark] [-M pmtudisc_option] [-N nodeinfo_option] [-w deadline] [-W timeout] [-p pattern] [-Q tos] [-s packetsize] [-S
sndbuf] [-t ttl] [-T timestamp option] [hop …] destination
-c [COUNT]
Stop after sending count ECHO_REQUEST packets. With deadline option, ping waits for count ECHO_REPLY packets, until the timeout expires.
from official man pages
ping -c 10 10.0.1.11
PING 10.0.1.11 (10.0.1.11) 56(84) bytes of data.
64 bytes from 10.0.1.11: icmp_seq=1 ttl=64 time=0.609 ms
64 bytes from 10.0.1.11: icmp_seq=2 ttl=64 time=0.624 ms
64 bytes from 10.0.1.11: icmp_seq=3 ttl=64 time=0.586 ms
64 bytes from 10.0.1.11: icmp_seq=4 ttl=64 time=0.603 ms
64 bytes from 10.0.1.11: icmp_seq=5 ttl=64 time=0.624 ms
64 bytes from 10.0.1.11: icmp_seq=6 ttl=64 time=0.602 ms
64 bytes from 10.0.1.11: icmp_seq=7 ttl=64 time=0.688 ms
64 bytes from 10.0.1.11: icmp_seq=8 ttl=64 time=0.620 ms
64 bytes from 10.0.1.11: icmp_seq=9 ttl=64 time=0.663 ms
64 bytes from 10.0.1.11: icmp_seq=10 ttl=64 time=0.604 ms
--- 10.0.1.11 ping statistics ---
10 packets transmitted, 10 received, 0% packet loss, time 9000ms
rtt min/avg/max/mdev = 0.586/0.622/0.688/0.035 ms-s [Packet Size]
Specifies the number of data bytes to be sent. The default is 56, which translates into 64 ICMP data bytes when combined with the 8 bytes of ICMP header data.
from official man pages
ping -s 64 -c 2 10.0.1.11
PING 10.0.1.11 (10.0.1.11) 64(92) bytes of data.
72 bytes from 10.0.1.11: icmp_seq=1 ttl=64 time=0.665 ms
72 bytes from 10.0.1.11: icmp_seq=2 ttl=64 time=0.612 ms
--- 10.0.1.11 ping statistics ---
2 packets transmitted, 2 received, 0% packet loss, time 1000ms
rtt min/avg/max/mdev = 0.612/0.638/0.665/0.036 msDIG
dig is a flexible tool for interrogating DNS name servers. It performs DNS lookups and displays the answers that are returned from the name server(s) that were queried.
dig www.samarthya.me
; <<>> DiG 9.11.4-P2-RedHat-9.11.4-16.P2.el7_8.6 <<>> www.samarthya.me
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 48626
;; flags: qr rd ra; QUERY: 1, ANSWER: 2, AUTHORITY: 0, ADDITIONAL: 1
;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 1220
;; QUESTION SECTION:
;www.samarthya.me. IN A
;; ANSWER SECTION:
www.samarthya.me. 13357 IN CNAME samarthya.me.
samarthya.me. 13357 IN A 148.72.168.185
;; Query time: 221 msec
;; SERVER: 192.19.189.10#53(192.19.189.10)
;; WHEN: Tue Oct 13 08:05:36 UTC 2020
;; MSG SIZE rcvd: 75ss
Utility to investigate sockets (Socket Statistics), similar to netstat
ss -e --extendedShows detailed information
ss -e
Netid State Recv-Q Send-Q Local Address:Port Peer Address:Port
u_str ESTAB 0 0 /run/dbus/system_bus_socket 14506 * 14457 <->
u_str ESTAB 0 0 * 13157 * 13158 <->
u_str ESTAB 0 0 * 17900 * 17901 <->
u_str ESTAB 0 0 * 17937 * 17936 <->
u_str ESTAB 0 0 * 17909 * 17910 <->
u_str ESTAB 0 0 * 17888 * 17887 <->
u_str ESTAB 0 0 * 17922 * 17921 ss -l # All listening portsss -l
Netid State Recv-Q Send-Q Local Address:Port Peer Address:Port
nl UNCONN 0 0 rtnl:kernel *
nl UNCONN 768 0 tcpdiag:kernel *
nl UNCONN 4352 0 tcpdiag:ss/11768 *
nl UNCONN 0 0 xfrm:kernel *
nl UNCONN 0 0 selinux:systemd/1 *
nl UNCONN 0 0 selinux:dbus-daemon/492 *
nl UNCONN 0 0 selinux:kernel *
nl UNCONN 0 0 selinux:dbus-daemon/492 *
nl UNCONN 0 0 selinux:systemd/1 *
nl UNCONN 0 0 audit:systemd/1 *
nl UNCONN 0 0 audit:auditd/422 *
nl UNCONN 0 0 audit:kernel *
nl UNCONN 0 0 fiblookup:kernel *
nl UNCONN 0 0 connector:kernel *
nl UNCONN 0 0 nft:kernel *
nl UNCONN 0 0 uevent:kernel *
nl UNCONN 0 0 uevent:systemd-udevd/393 *
nl UNCONN 0 0 uevent:systemd/1 *
nl UNCONN 0 0 uevent:-4117 *
nl UNCONN 0 0 uevent:tuned/907 *
nl UNCONN 0 0 uevent:-4107 * ss -s #summaryss -s
Total: 226 (kernel 0)
TCP: 8 (estab 2, closed 1, orphaned 0, synrecv 0, timewait 0/0), ports 0
Transport Total IP IPv6
* 0 - -
RAW 0 0 0
UDP 3 2 1
TCP 7 4 3
INET 10 6 4
FRAG 0 0 0 ss -ta #all tcp portsss -t -a
State Recv-Q Send-Q Local Address:Port Peer Address:Port
LISTEN 0 128 127.0.0.1:10248 *:*
LISTEN 0 128 *:sunrpc *:*
LISTEN 0 10 127.0.0.1:45556 *:*
LISTEN 0 5 192.168.122.1:domain *:*
LISTEN 0 128 *:ssh *:*
LISTEN 0 128 127.0.0.1:ipp *:*
LISTEN 0 100 127.0.0.1:smtp *:*
LISTEN 0 128 127.0.0.1:43483 *:*
ESTAB 0 0 10.80.241.80:ssh 10.52.43.159:51667
ESTAB 0 0 10.80.241.80:ssh 10.52.43.159:51356
ESTAB 0 0 10.80.241.80:39224 54.242.91.190:ssh
ESTAB 0 64 10.80.241.80:ssh 10.52.43.159:52010
LISTEN 0 128 [::]:7946 [::]:*
LISTEN 0 128 [::]:10250 [::]:*
LISTEN 0 128 [::]:sunrpc [::]:*
LISTEN 0 128 [::]:ssh [::]:*
LISTEN 0 128 [::1]:ipp [::]:*
LISTEN 0 100 [::1]:smtp [::]:* ss -tl # All TCP listening portsss -tl
State Recv-Q Send-Q Local Address:Port Peer Address:Port
LISTEN 0 128 127.0.0.1:10248 *:*
LISTEN 0 128 *:sunrpc *:*
LISTEN 0 10 127.0.0.1:45556 *:*
LISTEN 0 5 192.168.122.1:domain *:*
LISTEN 0 128 *:ssh *:*
LISTEN 0 128 127.0.0.1:ipp *:*
LISTEN 0 100 127.0.0.1:smtp *:*
LISTEN 0 128 127.0.0.1:43483 *:*
LISTEN 0 128 [::]:7946 [::]:*
LISTEN 0 128 [::]:10250 [::]:*
LISTEN 0 128 [::]:sunrpc [::]:*
LISTEN 0 128 [::]:ssh [::]:*
LISTEN 0 128 [::1]:ipp [::]:*
LISTEN 0 100 [::1]:smtp [::]:*